[{"issue":"1","language":[{"iso":"eng"}],"isi":1,"project":[{"name":"ISTplus - Postdoctoral Fellowships","call_identifier":"H2020","_id":"260C2330-B435-11E9-9278-68D0E5697425","grant_number":"754411"},{"_id":"25152F3A-B435-11E9-9278-68D0E5697425","call_identifier":"FP7","name":"Decoding the complexity of turbulence at its origin","grant_number":"306589"},{"grant_number":"662960","name":"Revisiting the Turbulence Problem Using Statistical Mechanics: Experimental Studies on Transitional and Turbulent Flows","_id":"238598C6-32DE-11EA-91FC-C7463DDC885E"}],"quality_controlled":"1","doi":"10.1103/PhysRevLett.128.014502","publication_identifier":{"issn":["0031-9007"],"eissn":["1079-7114"]},"article_type":"original","ec_funded":1,"scopus_import":"1","article_processing_charge":"No","publication":"Physical Review Letters","department":[{"_id":"BjHo"}],"pmid":1,"publisher":"American Physical Society","user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","article_number":"014502","title":"Phase transition to turbulence in spatially extended shear flows","arxiv":1,"day":"05","author":[{"id":"2C9AF1C2-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-1740-7635","full_name":"Klotz, Lukasz","first_name":"Lukasz","last_name":"Klotz"},{"full_name":"Lemoult, Grégoire M","id":"4787FE80-F248-11E8-B48F-1D18A9856A87","first_name":"Grégoire M","last_name":"Lemoult"},{"first_name":"Kerstin","last_name":"Avila","full_name":"Avila, Kerstin"},{"last_name":"Hof","first_name":"Björn","full_name":"Hof, Björn","orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87"}],"citation":{"ama":"Klotz L, Lemoult GM, Avila K, Hof B. Phase transition to turbulence in spatially extended shear flows. <i>Physical Review Letters</i>. 2022;128(1). doi:<a href=\"https://doi.org/10.1103/PhysRevLett.128.014502\">10.1103/PhysRevLett.128.014502</a>","mla":"Klotz, Lukasz, et al. “Phase Transition to Turbulence in Spatially Extended Shear Flows.” <i>Physical Review Letters</i>, vol. 128, no. 1, 014502, American Physical Society, 2022, doi:<a href=\"https://doi.org/10.1103/PhysRevLett.128.014502\">10.1103/PhysRevLett.128.014502</a>.","ista":"Klotz L, Lemoult GM, Avila K, Hof B. 2022. Phase transition to turbulence in spatially extended shear flows. Physical Review Letters. 128(1), 014502.","apa":"Klotz, L., Lemoult, G. M., Avila, K., &#38; Hof, B. (2022). Phase transition to turbulence in spatially extended shear flows. <i>Physical Review Letters</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevLett.128.014502\">https://doi.org/10.1103/PhysRevLett.128.014502</a>","ieee":"L. Klotz, G. M. Lemoult, K. Avila, and B. Hof, “Phase transition to turbulence in spatially extended shear flows,” <i>Physical Review Letters</i>, vol. 128, no. 1. American Physical Society, 2022.","chicago":"Klotz, Lukasz, Grégoire M Lemoult, Kerstin Avila, and Björn Hof. “Phase Transition to Turbulence in Spatially Extended Shear Flows.” <i>Physical Review Letters</i>. American Physical Society, 2022. <a href=\"https://doi.org/10.1103/PhysRevLett.128.014502\">https://doi.org/10.1103/PhysRevLett.128.014502</a>.","short":"L. Klotz, G.M. Lemoult, K. Avila, B. Hof, Physical Review Letters 128 (2022)."},"intvolume":"       128","status":"public","external_id":{"pmid":["35061458"],"isi":["000748271700010"],"arxiv":["2111.14894"]},"acknowledged_ssus":[{"_id":"M-Shop"}],"main_file_link":[{"url":"https://arxiv.org/abs/2111.14894","open_access":"1"}],"date_published":"2022-01-05T00:00:00Z","oa":1,"publication_status":"published","_id":"10654","year":"2022","acknowledgement":"We thank T.Menner, T.Asenov, P. Maier and the Miba machine shop of IST Austria for their valuable support in all technical aspects. We thank Marc Avila for comments on the manuscript. This work was supported by a grant from the Simons Foundation (662960, B.H.). We acknowledge the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement 306589 for financial support. K.A.\r\nacknowledges funding from the Central Research Development Fund of the University of Bremen, grant number ZF04B /2019/FB04 Avila Kerstin (”Independent Project for Postdocs”). L.K. was supported by the European Union’s Horizon 2020 Research and innovation programme under the Marie Sklodowska-Curie grant agreement  No. 754411.\r\n","date_created":"2022-01-23T23:01:28Z","volume":128,"month":"01","type":"journal_article","oa_version":"Preprint","abstract":[{"lang":"eng","text":"Directed percolation (DP) has recently emerged as a possible solution to the century old puzzle surrounding the transition to turbulence. Multiple model studies reported DP exponents, however, experimental evidence is limited since the largest possible observation times are orders of magnitude shorter than the flows’ characteristic timescales. An exception is cylindrical Couette flow where the limit is not temporal, but rather the realizable system size. We present experiments in a Couette setup of unprecedented azimuthal and axial aspect ratios. Approaching the critical point to within less than 0.1% we determine five critical exponents, all of which are in excellent agreement with the 2+1D DP universality class. The complex dynamics encountered at \r\nthe onset of turbulence can hence be fully rationalized within the framework of statistical mechanics."}],"date_updated":"2023-08-02T13:59:19Z"},{"language":[{"iso":"eng"}],"project":[{"name":"Decoding the complexity of turbulence at its origin","_id":"25152F3A-B435-11E9-9278-68D0E5697425","call_identifier":"FP7","grant_number":"306589"},{"grant_number":"737549","name":"Eliminating turbulence in oil pipelines","call_identifier":"H2020","_id":"25104D44-B435-11E9-9278-68D0E5697425"},{"grant_number":"HO 4393/1-2","_id":"25136C54-B435-11E9-9278-68D0E5697425","name":"Experimental studies of the turbulence transition and transport processes in turbulent Taylor-Couette currents"}],"doi":"10.15479/AT:ISTA:7258","publication_identifier":{"issn":["2663-337X"]},"ec_funded":1,"article_processing_charge":"No","publisher":"Institute of Science and Technology Austria","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","department":[{"_id":"BjHo"}],"title":"New approaches to reduce friction in turbulent pipe flow","degree_awarded":"PhD","author":[{"full_name":"Scarselli, Davide","orcid":"0000-0001-5227-4271","id":"40315C30-F248-11E8-B48F-1D18A9856A87","last_name":"Scarselli","first_name":"Davide"}],"file":[{"access_level":"closed","date_created":"2020-01-12T15:57:14Z","checksum":"4df1ab24e9896635106adde5a54615bf","file_id":"7259","date_updated":"2021-01-13T23:30:05Z","embargo_to":"open_access","creator":"dscarsel","file_size":26640830,"relation":"source_file","content_type":"application/zip","file_name":"2020_Scarselli_Thesis.zip"},{"file_name":"2020_Scarselli_Thesis.pdf","embargo":"2021-01-12","content_type":"application/pdf","relation":"main_file","file_size":8515844,"creator":"dscarsel","date_updated":"2021-01-13T23:30:05Z","file_id":"7260","checksum":"48659ab98e3414293c7a721385c2fd1c","date_created":"2020-01-12T15:56:14Z","access_level":"open_access"}],"day":"13","related_material":{"record":[{"relation":"part_of_dissertation","id":"6228","status":"public"},{"status":"public","id":"6486","relation":"part_of_dissertation"},{"id":"461","status":"public","relation":"part_of_dissertation"},{"relation":"part_of_dissertation","id":"422","status":"public"}]},"citation":{"short":"D. Scarselli, New Approaches to Reduce Friction in Turbulent Pipe Flow, Institute of Science and Technology Austria, 2020.","chicago":"Scarselli, Davide. “New Approaches to Reduce Friction in Turbulent Pipe Flow.” Institute of Science and Technology Austria, 2020. <a href=\"https://doi.org/10.15479/AT:ISTA:7258\">https://doi.org/10.15479/AT:ISTA:7258</a>.","ieee":"D. Scarselli, “New approaches to reduce friction in turbulent pipe flow,” Institute of Science and Technology Austria, 2020.","apa":"Scarselli, D. (2020). <i>New approaches to reduce friction in turbulent pipe flow</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/AT:ISTA:7258\">https://doi.org/10.15479/AT:ISTA:7258</a>","mla":"Scarselli, Davide. <i>New Approaches to Reduce Friction in Turbulent Pipe Flow</i>. Institute of Science and Technology Austria, 2020, doi:<a href=\"https://doi.org/10.15479/AT:ISTA:7258\">10.15479/AT:ISTA:7258</a>.","ista":"Scarselli D. 2020. New approaches to reduce friction in turbulent pipe flow. Institute of Science and Technology Austria.","ama":"Scarselli D. New approaches to reduce friction in turbulent pipe flow. 2020. doi:<a href=\"https://doi.org/10.15479/AT:ISTA:7258\">10.15479/AT:ISTA:7258</a>"},"alternative_title":["ISTA Thesis"],"status":"public","date_published":"2020-01-13T00:00:00Z","ddc":["532"],"supervisor":[{"orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","full_name":"Hof, Björn","first_name":"Björn","last_name":"Hof"}],"oa":1,"publication_status":"published","has_accepted_license":"1","_id":"7258","year":"2020","date_created":"2020-01-12T16:07:26Z","file_date_updated":"2021-01-13T23:30:05Z","page":"174","month":"01","oa_version":"None","type":"dissertation","abstract":[{"lang":"eng","text":"Many flows encountered in nature and applications are characterized by a chaotic motion known as turbulence. Turbulent flows generate intense friction with pipe walls and are responsible for considerable amounts of energy losses at world scale. The nature of turbulent friction and techniques aimed at reducing it have been subject of extensive research over the last century, but no definite answer has been found yet. In this thesis we show that in pipes at moderate turbulent Reynolds numbers friction is better described by the power law first introduced by Blasius and not by the Prandtl–von Kármán formula. At higher Reynolds numbers, large scale motions gradually become more important in the flow and can be related to the change in scaling of friction. Next, we present a series of new techniques that can relaminarize turbulence by suppressing a key mechanism that regenerates it at walls, the lift–up effect. In addition, we investigate the process of turbulence decay in several experiments and discuss the drag reduction potential. Finally, we examine the behavior of friction under pulsating conditions inspired by the human heart cycle and we show that under such circumstances turbulent friction can be reduced to produce energy savings."}],"date_updated":"2023-09-15T12:20:08Z"},{"year":"2019","_id":"6228","type":"journal_article","month":"05","oa_version":"Preprint","date_updated":"2024-03-25T23:30:20Z","abstract":[{"text":"Following  the  recent  observation  that  turbulent  pipe  flow  can  be  relaminarised  bya  relatively  simple  modification  of  the  mean  velocity  profile,  we  here  carry  out  aquantitative  experimental  investigation  of  this  phenomenon.  Our  study  confirms  thata  flat  velocity  profile  leads  to  a  collapse  of  turbulence  and  in  order  to  achieve  theblunted  profile  shape,  we  employ  a  moving  pipe  segment  that  is  briefly  and  rapidlyshifted  in  the  streamwise  direction.  The  relaminarisation  threshold  and  the  minimumshift  length  and  speeds  are  determined  as  a  function  of  Reynolds  number.  Althoughturbulence  is  still  active  after  the  acceleration  phase,  the  modulated  profile  possessesa  severely  decreased  lift-up  potential  as  measured  by  transient  growth.  As  shown,this  results  in  an  exponential  decay  of  fluctuations  and  the  flow  relaminarises.  Whilethis  method  can  be  easily  applied  at  low  to  moderate  flow  speeds,  the  minimumstreamwise  length  over  which  the  acceleration  needs  to  act  increases  linearly  with  theReynolds  number.","lang":"eng"}],"page":"934-948","date_created":"2019-04-07T21:59:14Z","volume":867,"external_id":{"arxiv":["1807.05357"],"isi":["000462606100001"]},"status":"public","citation":{"chicago":"Scarselli, Davide, Jakob Kühnen, and Björn Hof. “Relaminarising Pipe Flow by Wall Movement.” <i>Journal of Fluid Mechanics</i>. Cambridge University Press, 2019. <a href=\"https://doi.org/10.1017/jfm.2019.191\">https://doi.org/10.1017/jfm.2019.191</a>.","ieee":"D. Scarselli, J. Kühnen, and B. Hof, “Relaminarising pipe flow by wall movement,” <i>Journal of Fluid Mechanics</i>, vol. 867. Cambridge University Press, pp. 934–948, 2019.","short":"D. Scarselli, J. Kühnen, B. Hof, Journal of Fluid Mechanics 867 (2019) 934–948.","ama":"Scarselli D, Kühnen J, Hof B. Relaminarising pipe flow by wall movement. <i>Journal of Fluid Mechanics</i>. 2019;867:934-948. doi:<a href=\"https://doi.org/10.1017/jfm.2019.191\">10.1017/jfm.2019.191</a>","apa":"Scarselli, D., Kühnen, J., &#38; Hof, B. (2019). Relaminarising pipe flow by wall movement. <i>Journal of Fluid Mechanics</i>. Cambridge University Press. <a href=\"https://doi.org/10.1017/jfm.2019.191\">https://doi.org/10.1017/jfm.2019.191</a>","mla":"Scarselli, Davide, et al. “Relaminarising Pipe Flow by Wall Movement.” <i>Journal of Fluid Mechanics</i>, vol. 867, Cambridge University Press, 2019, pp. 934–48, doi:<a href=\"https://doi.org/10.1017/jfm.2019.191\">10.1017/jfm.2019.191</a>.","ista":"Scarselli D, Kühnen J, Hof B. 2019. Relaminarising pipe flow by wall movement. Journal of Fluid Mechanics. 867, 934–948."},"intvolume":"       867","related_material":{"link":[{"url":"https://doi.org/10.1017/jfm.2019.191","relation":"supplementary_material"}],"record":[{"relation":"dissertation_contains","id":"7258","status":"public"}]},"publication_status":"published","oa":1,"main_file_link":[{"url":"https://arxiv.org/abs/1807.05357","open_access":"1"}],"date_published":"2019-05-25T00:00:00Z","department":[{"_id":"BjHo"}],"user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","publisher":"Cambridge University Press","article_processing_charge":"No","scopus_import":"1","ec_funded":1,"publication":"Journal of Fluid Mechanics","day":"25","author":[{"orcid":"0000-0001-5227-4271","id":"40315C30-F248-11E8-B48F-1D18A9856A87","full_name":"Scarselli, Davide","last_name":"Scarselli","first_name":"Davide"},{"first_name":"Jakob","last_name":"Kühnen","orcid":"0000-0003-4312-0179","id":"3A47AE32-F248-11E8-B48F-1D18A9856A87","full_name":"Kühnen, Jakob"},{"orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","full_name":"Hof, Björn","first_name":"Björn","last_name":"Hof"}],"arxiv":1,"title":"Relaminarising pipe flow by wall movement","project":[{"grant_number":"306589","call_identifier":"FP7","_id":"25152F3A-B435-11E9-9278-68D0E5697425","name":"Decoding the complexity of turbulence at its origin"},{"grant_number":"737549","_id":"25104D44-B435-11E9-9278-68D0E5697425","call_identifier":"H2020","name":"Eliminating turbulence in oil pipelines"}],"language":[{"iso":"eng"}],"isi":1,"publication_identifier":{"eissn":["14697645"],"issn":["00221120"]},"quality_controlled":"1","doi":"10.1017/jfm.2019.191"},{"day":"01","author":[{"last_name":"Kühnen","first_name":"Jakob","orcid":"0000-0003-4312-0179","id":"3A47AE32-F248-11E8-B48F-1D18A9856A87","full_name":"Kühnen, Jakob"},{"last_name":"Scarselli","first_name":"Davide","full_name":"Scarselli, Davide","orcid":"0000-0001-5227-4271","id":"40315C30-F248-11E8-B48F-1D18A9856A87"},{"orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","full_name":"Hof, Björn","first_name":"Björn","last_name":"Hof"}],"article_number":"111105","arxiv":1,"title":"Relaminarization of pipe flow by means of 3D-printed shaped honeycombs","department":[{"_id":"BjHo"}],"publisher":"ASME","user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","article_type":"original","scopus_import":"1","ec_funded":1,"article_processing_charge":"No","publication":"Journal of Fluids Engineering","publication_identifier":{"issn":["00982202"],"eissn":["1528901X"]},"quality_controlled":"1","doi":"10.1115/1.4043494","project":[{"call_identifier":"FP7","_id":"25152F3A-B435-11E9-9278-68D0E5697425","name":"Decoding the complexity of turbulence at its origin","grant_number":"306589"}],"issue":"11","language":[{"iso":"eng"}],"isi":1,"oa_version":"Preprint","month":"11","type":"journal_article","abstract":[{"text":"Based on a novel control scheme, where a steady modification of the streamwise velocity profile leads to complete relaminarization of initially fully turbulent pipe flow, we investigate the applicability and usefulness of custom-shaped honeycombs for such control. The custom-shaped honeycombs are used as stationary flow management devices which generate specific modifications of the streamwise velocity profile. Stereoscopic particle image velocimetry and pressure drop measurements are used to investigate and capture the development of the relaminarizing flow downstream these devices. We compare the performance of straight (constant length across the radius of the pipe) honeycombs with custom-shaped ones (variable length across the radius) and try to determine the optimal shape for maximal relaminarization at minimal pressure loss. The optimally modified streamwise velocity profile is found to be M-shaped, and the maximum attainable Reynolds number for total relaminarization is found to be of the order of 10,000. Consequently, the respective reduction in skin friction downstream of the device is almost by a factor of 5. The break-even point, where the additional pressure drop caused by the device is balanced by the savings due to relaminarization and a net gain is obtained, corresponds to a downstream stretch of distances as low as approximately 100 pipe diameters of laminar flow.","lang":"eng"}],"date_updated":"2024-03-25T23:30:20Z","date_created":"2019-05-26T21:59:13Z","volume":141,"year":"2019","_id":"6486","oa":1,"publication_status":"published","acknowledged_ssus":[{"_id":"M-Shop"}],"main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1809.07625"}],"date_published":"2019-11-01T00:00:00Z","status":"public","external_id":{"arxiv":["1809.07625"],"isi":["000487748600005"]},"citation":{"ama":"Kühnen J, Scarselli D, Hof B. Relaminarization of pipe flow by means of 3D-printed shaped honeycombs. <i>Journal of Fluids Engineering</i>. 2019;141(11). doi:<a href=\"https://doi.org/10.1115/1.4043494\">10.1115/1.4043494</a>","apa":"Kühnen, J., Scarselli, D., &#38; Hof, B. (2019). Relaminarization of pipe flow by means of 3D-printed shaped honeycombs. <i>Journal of Fluids Engineering</i>. ASME. <a href=\"https://doi.org/10.1115/1.4043494\">https://doi.org/10.1115/1.4043494</a>","mla":"Kühnen, Jakob, et al. “Relaminarization of Pipe Flow by Means of 3D-Printed Shaped Honeycombs.” <i>Journal of Fluids Engineering</i>, vol. 141, no. 11, 111105, ASME, 2019, doi:<a href=\"https://doi.org/10.1115/1.4043494\">10.1115/1.4043494</a>.","ista":"Kühnen J, Scarselli D, Hof B. 2019. Relaminarization of pipe flow by means of 3D-printed shaped honeycombs. Journal of Fluids Engineering. 141(11), 111105.","chicago":"Kühnen, Jakob, Davide Scarselli, and Björn Hof. “Relaminarization of Pipe Flow by Means of 3D-Printed Shaped Honeycombs.” <i>Journal of Fluids Engineering</i>. ASME, 2019. <a href=\"https://doi.org/10.1115/1.4043494\">https://doi.org/10.1115/1.4043494</a>.","ieee":"J. Kühnen, D. Scarselli, and B. Hof, “Relaminarization of pipe flow by means of 3D-printed shaped honeycombs,” <i>Journal of Fluids Engineering</i>, vol. 141, no. 11. ASME, 2019.","short":"J. Kühnen, D. Scarselli, B. Hof, Journal of Fluids Engineering 141 (2019)."},"intvolume":"       141","related_material":{"record":[{"status":"public","id":"7258","relation":"dissertation_contains"}]}},{"author":[{"first_name":"George H","last_name":"Choueiri","full_name":"Choueiri, George H","id":"448BD5BC-F248-11E8-B48F-1D18A9856A87"},{"first_name":"Jose M","last_name":"Lopez Alonso","full_name":"Lopez Alonso, Jose M","id":"40770848-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-0384-2022"},{"id":"3A374330-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-2057-2754","full_name":"Hof, Björn","last_name":"Hof","first_name":"Björn"}],"day":"19","article_number":"124501","title":"Exceeding the asymptotic limit of polymer drag reduction","publist_id":"7537","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","publisher":"American Physical Society","department":[{"_id":"BjHo"}],"publication":"Physical Review Letters","article_processing_charge":"No","ec_funded":1,"scopus_import":"1","doi":"10.1103/PhysRevLett.120.124501","quality_controlled":"1","project":[{"grant_number":"291734","_id":"25681D80-B435-11E9-9278-68D0E5697425","call_identifier":"FP7","name":"International IST Postdoc Fellowship Programme"},{"grant_number":"306589","_id":"25152F3A-B435-11E9-9278-68D0E5697425","call_identifier":"FP7","name":"Decoding the complexity of turbulence at its origin"}],"isi":1,"issue":"12","language":[{"iso":"eng"}],"month":"03","type":"journal_article","oa_version":"Preprint","abstract":[{"text":"The drag of turbulent flows can be drastically decreased by adding small amounts of high molecular weight polymers. While drag reduction initially increases with polymer concentration, it eventually saturates to what is known as the maximum drag reduction (MDR) asymptote; this asymptote is generally attributed to the dynamics being reduced to a marginal yet persistent state of subdued turbulent motion. Contrary to this accepted view, we show that, for an appropriate choice of parameters, polymers can reduce the drag beyond the suggested asymptotic limit, eliminating turbulence and giving way to laminar flow. At higher polymer concentrations, however, the laminar state becomes unstable, resulting in a fluctuating flow with the characteristic drag of the MDR asymptote. Our findings indicate that the asymptotic state is hence dynamically disconnected from ordinary turbulence. © 2018 American Physical Society.","lang":"eng"}],"date_updated":"2023-10-10T13:27:44Z","volume":120,"date_created":"2018-12-11T11:45:51Z","acknowledgement":"The authors thank Philipp Maier and the IST Austria workshop for their dedicated technical support.","year":"2018","_id":"328","oa":1,"publication_status":"published","date_published":"2018-03-19T00:00:00Z","acknowledged_ssus":[{"_id":"SSU"}],"main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1703.06271"}],"external_id":{"isi":["000427804000005"]},"status":"public","intvolume":"       120","citation":{"chicago":"Choueiri, George H, Jose M Lopez Alonso, and Björn Hof. “Exceeding the Asymptotic Limit of Polymer Drag Reduction.” <i>Physical Review Letters</i>. American Physical Society, 2018. <a href=\"https://doi.org/10.1103/PhysRevLett.120.124501\">https://doi.org/10.1103/PhysRevLett.120.124501</a>.","ieee":"G. H. Choueiri, J. M. Lopez Alonso, and B. Hof, “Exceeding the asymptotic limit of polymer drag reduction,” <i>Physical Review Letters</i>, vol. 120, no. 12. American Physical Society, 2018.","short":"G.H. Choueiri, J.M. Lopez Alonso, B. Hof, Physical Review Letters 120 (2018).","ama":"Choueiri GH, Lopez Alonso JM, Hof B. Exceeding the asymptotic limit of polymer drag reduction. <i>Physical Review Letters</i>. 2018;120(12). doi:<a href=\"https://doi.org/10.1103/PhysRevLett.120.124501\">10.1103/PhysRevLett.120.124501</a>","apa":"Choueiri, G. H., Lopez Alonso, J. M., &#38; Hof, B. (2018). Exceeding the asymptotic limit of polymer drag reduction. <i>Physical Review Letters</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevLett.120.124501\">https://doi.org/10.1103/PhysRevLett.120.124501</a>","ista":"Choueiri GH, Lopez Alonso JM, Hof B. 2018. Exceeding the asymptotic limit of polymer drag reduction. Physical Review Letters. 120(12), 124501.","mla":"Choueiri, George H., et al. “Exceeding the Asymptotic Limit of Polymer Drag Reduction.” <i>Physical Review Letters</i>, vol. 120, no. 12, 124501, American Physical Society, 2018, doi:<a href=\"https://doi.org/10.1103/PhysRevLett.120.124501\">10.1103/PhysRevLett.120.124501</a>."}},{"publist_id":"7360","title":"Destabilizing turbulence in pipe flow","day":"08","author":[{"last_name":"Kühnen","first_name":"Jakob","full_name":"Kühnen, Jakob","orcid":"0000-0003-4312-0179","id":"3A47AE32-F248-11E8-B48F-1D18A9856A87"},{"first_name":"Baofang","last_name":"Song","full_name":"Song, Baofang"},{"first_name":"Davide","last_name":"Scarselli","orcid":"0000-0001-5227-4271","id":"40315C30-F248-11E8-B48F-1D18A9856A87","full_name":"Scarselli, Davide"},{"id":"3EA1010E-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-0423-5010","full_name":"Budanur, Nazmi B","first_name":"Nazmi B","last_name":"Budanur"},{"id":"3BE60946-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-4844-6311","full_name":"Riedl, Michael","last_name":"Riedl","first_name":"Michael"},{"full_name":"Willis, Ashley","last_name":"Willis","first_name":"Ashley"},{"full_name":"Avila, Marc","last_name":"Avila","first_name":"Marc"},{"full_name":"Hof, Björn","orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","last_name":"Hof","first_name":"Björn"}],"scopus_import":"1","ec_funded":1,"article_processing_charge":"No","publication":"Nature Physics","department":[{"_id":"BjHo"}],"publisher":"Nature Publishing Group","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","quality_controlled":"1","doi":"10.1038/s41567-017-0018-3","language":[{"iso":"eng"}],"isi":1,"project":[{"grant_number":"306589","call_identifier":"FP7","_id":"25152F3A-B435-11E9-9278-68D0E5697425","name":"Decoding the complexity of turbulence at its origin"},{"call_identifier":"H2020","_id":"25104D44-B435-11E9-9278-68D0E5697425","name":"Eliminating turbulence in oil pipelines","grant_number":"737549"}],"date_created":"2018-12-11T11:46:36Z","volume":14,"month":"01","oa_version":"Preprint","type":"journal_article","abstract":[{"text":"Turbulence is the major cause of friction losses in transport processes and it is responsible for a drastic drag increase in flows over bounding surfaces. While much effort is invested into developing ways to control and reduce turbulence intensities, so far no methods exist to altogether eliminate turbulence if velocities are sufficiently large. We demonstrate for pipe flow that appropriate distortions to the velocity profile lead to a complete collapse of turbulence and subsequently friction losses are reduced by as much as 90%. Counterintuitively, the return to laminar motion is accomplished by initially increasing turbulence intensities or by transiently amplifying wall shear. Since neither the Reynolds number nor the shear stresses decrease (the latter often increase), these measures are not indicative of turbulence collapse. Instead, an amplification mechanism                      measuring the interaction between eddies and the mean shear is found to set a threshold below which turbulence is suppressed beyond recovery.","lang":"eng"}],"date_updated":"2024-03-25T23:30:20Z","page":"386-390","_id":"461","year":"2018","acknowledgement":"We acknowledge the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement 306589, the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 737549) and the Deutsche Forschungsgemeinschaft (Project No. FOR 1182) for financial support. We thank our technician P. Maier for providing highly valuable ideas and greatly supporting us in all technical aspects. We thank M. Schaner for technical drawings, construction and design. We thank M. Schwegel for a Matlab code to post-process experimental data.","main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1711.06543"}],"date_published":"2018-01-08T00:00:00Z","publication_status":"published","oa":1,"citation":{"ama":"Kühnen J, Song B, Scarselli D, et al. Destabilizing turbulence in pipe flow. <i>Nature Physics</i>. 2018;14:386-390. doi:<a href=\"https://doi.org/10.1038/s41567-017-0018-3\">10.1038/s41567-017-0018-3</a>","mla":"Kühnen, Jakob, et al. “Destabilizing Turbulence in Pipe Flow.” <i>Nature Physics</i>, vol. 14, Nature Publishing Group, 2018, pp. 386–90, doi:<a href=\"https://doi.org/10.1038/s41567-017-0018-3\">10.1038/s41567-017-0018-3</a>.","ista":"Kühnen J, Song B, Scarselli D, Budanur NB, Riedl M, Willis A, Avila M, Hof B. 2018. Destabilizing turbulence in pipe flow. Nature Physics. 14, 386–390.","apa":"Kühnen, J., Song, B., Scarselli, D., Budanur, N. B., Riedl, M., Willis, A., … Hof, B. (2018). Destabilizing turbulence in pipe flow. <i>Nature Physics</i>. Nature Publishing Group. <a href=\"https://doi.org/10.1038/s41567-017-0018-3\">https://doi.org/10.1038/s41567-017-0018-3</a>","ieee":"J. Kühnen <i>et al.</i>, “Destabilizing turbulence in pipe flow,” <i>Nature Physics</i>, vol. 14. Nature Publishing Group, pp. 386–390, 2018.","chicago":"Kühnen, Jakob, Baofang Song, Davide Scarselli, Nazmi B Budanur, Michael Riedl, Ashley Willis, Marc Avila, and Björn Hof. “Destabilizing Turbulence in Pipe Flow.” <i>Nature Physics</i>. Nature Publishing Group, 2018. <a href=\"https://doi.org/10.1038/s41567-017-0018-3\">https://doi.org/10.1038/s41567-017-0018-3</a>.","short":"J. Kühnen, B. Song, D. Scarselli, N.B. Budanur, M. Riedl, A. Willis, M. Avila, B. Hof, Nature Physics 14 (2018) 386–390."},"intvolume":"        14","related_material":{"record":[{"id":"12726","status":"public","relation":"dissertation_contains"},{"relation":"dissertation_contains","status":"public","id":"14530"},{"status":"public","id":"7258","relation":"dissertation_contains"}]},"external_id":{"isi":["000429434100020"]},"status":"public"},{"intvolume":"       839","citation":{"chicago":"Vasudevan, Mukund, and Björn Hof. “The Critical Point of the Transition to Turbulence in Pipe Flow.” <i>Journal of Fluid Mechanics</i>. Cambridge University Press, 2018. <a href=\"https://doi.org/10.1017/jfm.2017.923\">https://doi.org/10.1017/jfm.2017.923</a>.","ieee":"M. Vasudevan and B. Hof, “The critical point of the transition to turbulence in pipe flow,” <i>Journal of Fluid Mechanics</i>, vol. 839. Cambridge University Press, pp. 76–94, 2018.","short":"M. Vasudevan, B. Hof, Journal of Fluid Mechanics 839 (2018) 76–94.","ama":"Vasudevan M, Hof B. The critical point of the transition to turbulence in pipe flow. <i>Journal of Fluid Mechanics</i>. 2018;839:76-94. doi:<a href=\"https://doi.org/10.1017/jfm.2017.923\">10.1017/jfm.2017.923</a>","apa":"Vasudevan, M., &#38; Hof, B. (2018). The critical point of the transition to turbulence in pipe flow. <i>Journal of Fluid Mechanics</i>. Cambridge University Press. <a href=\"https://doi.org/10.1017/jfm.2017.923\">https://doi.org/10.1017/jfm.2017.923</a>","mla":"Vasudevan, Mukund, and Björn Hof. “The Critical Point of the Transition to Turbulence in Pipe Flow.” <i>Journal of Fluid Mechanics</i>, vol. 839, Cambridge University Press, 2018, pp. 76–94, doi:<a href=\"https://doi.org/10.1017/jfm.2017.923\">10.1017/jfm.2017.923</a>.","ista":"Vasudevan M, Hof B. 2018. The critical point of the transition to turbulence in pipe flow. Journal of Fluid Mechanics. 839, 76–94."},"status":"public","external_id":{"isi":["000437858300003"],"arxiv":["1709.06372"]},"date_published":"2018-03-25T00:00:00Z","main_file_link":[{"url":"https://arxiv.org/abs/1709.06372","open_access":"1"}],"publication_status":"published","oa":1,"_id":"5996","acknowledgement":" We  also  thank  Philipp  Maier  and  the  IST  Austria  workshop  for  theirdedicated technical support","year":"2018","volume":839,"date_created":"2019-02-14T12:50:50Z","page":"76-94","month":"03","type":"journal_article","oa_version":"Preprint","date_updated":"2023-09-19T14:37:49Z","abstract":[{"lang":"eng","text":"In pipes, turbulence sets in despite the linear stability of the laminar Hagen–Poiseuille flow. The Reynolds number ( ) for which turbulence first appears in a given experiment – the ‘natural transition point’ – depends on imperfections of the set-up, or, more precisely, on the magnitude of finite amplitude perturbations. At onset, turbulence typically only occupies a certain fraction of the flow, and this fraction equally is found to differ from experiment to experiment. Despite these findings, Reynolds proposed that after sufficiently long times, flows may settle to steady conditions: below a critical velocity, flows should (regardless of initial conditions) always return to laminar, while above this velocity, eddying motion should persist. As will be shown, even in pipes several thousand diameters long, the spatio-temporal intermittent flow patterns observed at the end of the pipe strongly depend on the initial conditions, and there is no indication that different flow patterns would eventually settle to a (statistical) steady state. Exploiting the fact that turbulent puffs do not age (i.e. they are memoryless), we continuously recreate the puff sequence exiting the pipe at the pipe entrance, and in doing so introduce periodic boundary conditions for the puff pattern. This procedure allows us to study the evolution of the flow patterns for arbitrary long times, and we find that after times in excess of advective time units, indeed a statistical steady state is reached. Although the resulting flows remain spatio-temporally intermittent, puff splitting and decay rates eventually reach a balance, so that the turbulent fraction fluctuates around a well-defined level which only depends on . In accordance with Reynolds’ proposition, we find that at lower (here 2020), flows eventually always resume to laminar, while for higher ( ), turbulence persists. The critical point for pipe flow hence falls in the interval of $2020 , which is in very good agreement with the recently proposed value of . The latter estimate was based on single-puff statistics and entirely neglected puff interactions. Unlike in typical contact processes where such interactions strongly affect the percolation threshold, in pipe flow, the critical point is only marginally influenced. Interactions, on the other hand, are responsible for the approach to the statistical steady state. As shown, they strongly affect the resulting flow patterns, where they cause ‘puff clustering’, and these regions of large puff densities are observed to travel across the puff pattern in a wave-like fashion."}],"isi":1,"language":[{"iso":"eng"}],"project":[{"_id":"25152F3A-B435-11E9-9278-68D0E5697425","call_identifier":"FP7","name":"Decoding the complexity of turbulence at its origin","grant_number":"306589"}],"doi":"10.1017/jfm.2017.923","quality_controlled":"1","publication_identifier":{"issn":["0022-1120"],"eissn":["1469-7645"]},"publication":"Journal of Fluid Mechanics","article_type":"original","ec_funded":1,"article_processing_charge":"No","scopus_import":"1","publisher":"Cambridge University Press","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","department":[{"_id":"BjHo"}],"title":"The critical point of the transition to turbulence in pipe flow","arxiv":1,"author":[{"last_name":"Vasudevan","first_name":"Mukund","full_name":"Vasudevan, Mukund","id":"3C5A959A-F248-11E8-B48F-1D18A9856A87"},{"orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","full_name":"Hof, Björn","last_name":"Hof","first_name":"Björn"}],"day":"25"},{"isi":1,"language":[{"iso":"eng"}],"issue":"4","project":[{"name":"Decoding the complexity of turbulence at its origin","_id":"25152F3A-B435-11E9-9278-68D0E5697425","call_identifier":"FP7","grant_number":"306589"}],"doi":"10.1007/s10494-018-9896-4","quality_controlled":"1","publication":"Flow Turbulence and Combustion","ec_funded":1,"scopus_import":"1","article_processing_charge":"Yes (via OA deal)","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"publisher":"Springer","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","department":[{"_id":"BjHo"}],"title":"Relaminarization by steady modification of the streamwise velocity profile in a pipe","publist_id":"7401","author":[{"id":"3A47AE32-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-4312-0179","full_name":"Kühnen, Jakob","last_name":"Kühnen","first_name":"Jakob"},{"orcid":"0000-0001-5227-4271","id":"40315C30-F248-11E8-B48F-1D18A9856A87","full_name":"Scarselli, Davide","last_name":"Scarselli","first_name":"Davide"},{"id":"316CE034-F248-11E8-B48F-1D18A9856A87","full_name":"Schaner, Markus","first_name":"Markus","last_name":"Schaner"},{"first_name":"Björn","last_name":"Hof","full_name":"Hof, Björn","orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87"}],"day":"01","license":"https://creativecommons.org/licenses/by/4.0/","file":[{"creator":"dernst","relation":"main_file","content_type":"application/pdf","file_size":2210020,"file_name":"2018_FlowTurbulenceCombust_Kuehnen.pdf","access_level":"open_access","date_created":"2018-12-17T15:52:37Z","checksum":"d7c0bade150faabca150b0a9986e60ca","date_updated":"2020-07-14T12:46:25Z","file_id":"5717"}],"related_material":{"record":[{"id":"7258","status":"public","relation":"dissertation_contains"}]},"intvolume":"       100","citation":{"short":"J. Kühnen, D. Scarselli, M. Schaner, B. Hof, Flow Turbulence and Combustion 100 (2018) 919–942.","ieee":"J. Kühnen, D. Scarselli, M. Schaner, and B. Hof, “Relaminarization by steady modification of the streamwise velocity profile in a pipe,” <i>Flow Turbulence and Combustion</i>, vol. 100, no. 4. Springer, pp. 919–942, 2018.","chicago":"Kühnen, Jakob, Davide Scarselli, Markus Schaner, and Björn Hof. “Relaminarization by Steady Modification of the Streamwise Velocity Profile in a Pipe.” <i>Flow Turbulence and Combustion</i>. Springer, 2018. <a href=\"https://doi.org/10.1007/s10494-018-9896-4\">https://doi.org/10.1007/s10494-018-9896-4</a>.","ista":"Kühnen J, Scarselli D, Schaner M, Hof B. 2018. Relaminarization by steady modification of the streamwise velocity profile in a pipe. Flow Turbulence and Combustion. 100(4), 919–942.","mla":"Kühnen, Jakob, et al. “Relaminarization by Steady Modification of the Streamwise Velocity Profile in a Pipe.” <i>Flow Turbulence and Combustion</i>, vol. 100, no. 4, Springer, 2018, pp. 919–42, doi:<a href=\"https://doi.org/10.1007/s10494-018-9896-4\">10.1007/s10494-018-9896-4</a>.","apa":"Kühnen, J., Scarselli, D., Schaner, M., &#38; Hof, B. (2018). Relaminarization by steady modification of the streamwise velocity profile in a pipe. <i>Flow Turbulence and Combustion</i>. Springer. <a href=\"https://doi.org/10.1007/s10494-018-9896-4\">https://doi.org/10.1007/s10494-018-9896-4</a>","ama":"Kühnen J, Scarselli D, Schaner M, Hof B. Relaminarization by steady modification of the streamwise velocity profile in a pipe. <i>Flow Turbulence and Combustion</i>. 2018;100(4):919-942. doi:<a href=\"https://doi.org/10.1007/s10494-018-9896-4\">10.1007/s10494-018-9896-4</a>"},"status":"public","external_id":{"isi":["000433113900004"]},"ddc":["530"],"date_published":"2018-01-01T00:00:00Z","oa":1,"publication_status":"published","has_accepted_license":"1","_id":"422","year":"2018","volume":100,"file_date_updated":"2020-07-14T12:46:25Z","date_created":"2018-12-11T11:46:23Z","page":"919 - 942","abstract":[{"text":"We show that a rather simple, steady modification of the streamwise velocity profile in a pipe can lead to a complete collapse of turbulence and the flow fully relaminarizes. Two different devices, a stationary obstacle (inset) and a device which injects fluid through an annular gap close to the wall, are used to control the flow. Both devices modify the streamwise velocity profile such that the flow in the center of the pipe is decelerated and the flow in the near wall region is accelerated. We present measurements with stereoscopic particle image velocimetry to investigate and capture the development of the relaminarizing flow downstream these devices and the specific circumstances responsible for relaminarization. We find total relaminarization up to Reynolds numbers of 6000, where the skin friction in the far downstream distance is reduced by a factor of 3.4 due to relaminarization. In a smooth straight pipe the flow remains completely laminar downstream of the control. Furthermore, we show that transient (temporary) relaminarization in a spatially confined region right downstream the devices occurs also at much higher Reynolds numbers, accompanied by a significant local skin friction drag reduction. The underlying physical mechanism of relaminarization is attributed to a weakening of the near-wall turbulence production cycle.","lang":"eng"}],"date_updated":"2024-03-25T23:30:20Z","type":"journal_article","month":"01","oa_version":"Published Version"},{"user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","publisher":"Cambridge University Press","department":[{"_id":"BjHo"}],"publication":"Journal of Fluid Mechanics","ec_funded":1,"scopus_import":"1","article_processing_charge":"No","author":[{"last_name":"Song","first_name":"Baofang","full_name":"Song, Baofang"},{"first_name":"Dwight","last_name":"Barkley","full_name":"Barkley, Dwight"},{"last_name":"Hof","first_name":"Björn","id":"3A374330-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-2057-2754","full_name":"Hof, Björn"},{"first_name":"Marc","last_name":"Avila","full_name":"Avila, Marc"}],"day":"25","title":"Speed and structure of turbulent fronts in pipe flow","publist_id":"6290","project":[{"grant_number":"306589","name":"Decoding the complexity of turbulence at its origin","_id":"25152F3A-B435-11E9-9278-68D0E5697425","call_identifier":"FP7"}],"isi":1,"language":[{"iso":"eng"}],"publication_identifier":{"issn":["00221120"]},"doi":"10.1017/jfm.2017.14","quality_controlled":"1","year":"2017","_id":"1087","page":"1045 - 1059","abstract":[{"lang":"eng","text":"Using extensive direct numerical simulations, the dynamics of laminar-turbulent fronts in pipe flow is investigated for Reynolds numbers between and 5500. We here investigate the physical distinction between the fronts of weak and strong slugs both by analysing the turbulent kinetic energy budget and by comparing the downstream front motion to the advection speed of bulk turbulent structures. Our study shows that weak downstream fronts travel slower than turbulent structures in the bulk and correspond to decaying turbulence at the front. At the downstream front speed becomes faster than the advection speed, marking the onset of strong fronts. In contrast to weak fronts, turbulent eddies are generated at strong fronts by feeding on the downstream laminar flow. Our study also suggests that temporal fluctuations of production and dissipation at the downstream laminar-turbulent front drive the dynamical switches between the two types of front observed up to."}],"date_updated":"2023-09-20T11:47:22Z","oa_version":"Submitted Version","month":"02","type":"journal_article","volume":813,"date_created":"2018-12-11T11:50:04Z","status":"public","external_id":{"isi":["000394376400044"]},"intvolume":"       813","citation":{"short":"B. Song, D. Barkley, B. Hof, M. Avila, Journal of Fluid Mechanics 813 (2017) 1045–1059.","ieee":"B. Song, D. Barkley, B. Hof, and M. Avila, “Speed and structure of turbulent fronts in pipe flow,” <i>Journal of Fluid Mechanics</i>, vol. 813. Cambridge University Press, pp. 1045–1059, 2017.","chicago":"Song, Baofang, Dwight Barkley, Björn Hof, and Marc Avila. “Speed and Structure of Turbulent Fronts in Pipe Flow.” <i>Journal of Fluid Mechanics</i>. Cambridge University Press, 2017. <a href=\"https://doi.org/10.1017/jfm.2017.14\">https://doi.org/10.1017/jfm.2017.14</a>.","mla":"Song, Baofang, et al. “Speed and Structure of Turbulent Fronts in Pipe Flow.” <i>Journal of Fluid Mechanics</i>, vol. 813, Cambridge University Press, 2017, pp. 1045–59, doi:<a href=\"https://doi.org/10.1017/jfm.2017.14\">10.1017/jfm.2017.14</a>.","ista":"Song B, Barkley D, Hof B, Avila M. 2017. Speed and structure of turbulent fronts in pipe flow. Journal of Fluid Mechanics. 813, 1045–1059.","apa":"Song, B., Barkley, D., Hof, B., &#38; Avila, M. (2017). Speed and structure of turbulent fronts in pipe flow. <i>Journal of Fluid Mechanics</i>. Cambridge University Press. <a href=\"https://doi.org/10.1017/jfm.2017.14\">https://doi.org/10.1017/jfm.2017.14</a>","ama":"Song B, Barkley D, Hof B, Avila M. Speed and structure of turbulent fronts in pipe flow. <i>Journal of Fluid Mechanics</i>. 2017;813:1045-1059. doi:<a href=\"https://doi.org/10.1017/jfm.2017.14\">10.1017/jfm.2017.14</a>"},"oa":1,"publication_status":"published","date_published":"2017-02-25T00:00:00Z","main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1603.04077"}],"acknowledged_ssus":[{"_id":"ScienComp"}]},{"language":[{"iso":"eng"}],"isi":1,"project":[{"_id":"25152F3A-B435-11E9-9278-68D0E5697425","call_identifier":"FP7","name":"Decoding the complexity of turbulence at its origin","grant_number":"306589"}],"quality_controlled":"1","doi":"10.1017/jfm.2017.620","publication_identifier":{"issn":["00221120"]},"ec_funded":1,"article_processing_charge":"No","scopus_import":"1","publication":"Journal of Fluid Mechanics","department":[{"_id":"BjHo"}],"publisher":"Cambridge University Press","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","publist_id":"6922","title":"Transition to turbulence in pulsating pipe flow","day":"25","author":[{"id":"3454D55E-F248-11E8-B48F-1D18A9856A87","full_name":"Xu, Duo","last_name":"Xu","first_name":"Duo"},{"first_name":"Sascha","last_name":"Warnecke","full_name":"Warnecke, Sascha"},{"first_name":"Baofang","last_name":"Song","full_name":"Song, Baofang"},{"full_name":"Ma, Xingyu","id":"34BADBA6-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-0179-9737","first_name":"Xingyu","last_name":"Ma"},{"full_name":"Hof, Björn","orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","last_name":"Hof","first_name":"Björn"}],"citation":{"ama":"Xu D, Warnecke S, Song B, Ma X, Hof B. Transition to turbulence in pulsating pipe flow. <i>Journal of Fluid Mechanics</i>. 2017;831:418-432. doi:<a href=\"https://doi.org/10.1017/jfm.2017.620\">10.1017/jfm.2017.620</a>","ista":"Xu D, Warnecke S, Song B, Ma X, Hof B. 2017. Transition to turbulence in pulsating pipe flow. Journal of Fluid Mechanics. 831, 418–432.","mla":"Xu, Duo, et al. “Transition to Turbulence in Pulsating Pipe Flow.” <i>Journal of Fluid Mechanics</i>, vol. 831, Cambridge University Press, 2017, pp. 418–32, doi:<a href=\"https://doi.org/10.1017/jfm.2017.620\">10.1017/jfm.2017.620</a>.","apa":"Xu, D., Warnecke, S., Song, B., Ma, X., &#38; Hof, B. (2017). Transition to turbulence in pulsating pipe flow. <i>Journal of Fluid Mechanics</i>. Cambridge University Press. <a href=\"https://doi.org/10.1017/jfm.2017.620\">https://doi.org/10.1017/jfm.2017.620</a>","ieee":"D. Xu, S. Warnecke, B. Song, X. Ma, and B. Hof, “Transition to turbulence in pulsating pipe flow,” <i>Journal of Fluid Mechanics</i>, vol. 831. Cambridge University Press, pp. 418–432, 2017.","chicago":"Xu, Duo, Sascha Warnecke, Baofang Song, Xingyu Ma, and Björn Hof. “Transition to Turbulence in Pulsating Pipe Flow.” <i>Journal of Fluid Mechanics</i>. Cambridge University Press, 2017. <a href=\"https://doi.org/10.1017/jfm.2017.620\">https://doi.org/10.1017/jfm.2017.620</a>.","short":"D. Xu, S. Warnecke, B. Song, X. Ma, B. Hof, Journal of Fluid Mechanics 831 (2017) 418–432."},"intvolume":"       831","status":"public","external_id":{"isi":["000412934800005"]},"main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1709.03738"}],"date_published":"2017-11-25T00:00:00Z","publication_status":"published","oa":1,"_id":"745","year":"2017","date_created":"2018-12-11T11:48:17Z","volume":831,"abstract":[{"lang":"eng","text":"Fluid flows in nature and applications are frequently subject to periodic velocity modulations. Surprisingly, even for the generic case of flow through a straight pipe, there is little consensus regarding the influence of pulsation on the transition threshold to turbulence: while most studies predict a monotonically increasing threshold with pulsation frequency (i.e. Womersley number, ), others observe a decreasing threshold for identical parameters and only observe an increasing threshold at low . In the present study we apply recent advances in the understanding of transition in steady shear flows to pulsating pipe flow. For moderate pulsation amplitudes we find that the first instability encountered is subcritical (i.e. requiring finite amplitude disturbances) and gives rise to localized patches of turbulence ('puffs') analogous to steady pipe flow. By monitoring the impact of pulsation on the lifetime of turbulence we map the onset of turbulence in parameter space. Transition in pulsatile flow can be separated into three regimes. At small Womersley numbers the dynamics is dominated by the decay turbulence suffers during the slower part of the cycle and hence transition is delayed significantly. As shown in this regime thresholds closely agree with estimates based on a quasi-steady flow assumption only taking puff decay rates into account. The transition point predicted in the zero limit equals to the critical point for steady pipe flow offset by the oscillation Reynolds number (i.e. the dimensionless oscillation amplitude). In the high frequency limit on the other hand, puff lifetimes are identical to those in steady pipe flow and hence the transition threshold appears to be unaffected by flow pulsation. In the intermediate frequency regime the transition threshold sharply drops (with increasing ) from the decay dominated (quasi-steady) threshold to the steady pipe flow level."}],"date_updated":"2023-09-27T12:28:12Z","type":"journal_article","month":"11","oa_version":"Submitted Version","page":"418 - 432"},{"year":"2017","_id":"661","month":"03","oa_version":"Submitted Version","type":"journal_article","abstract":[{"text":"During embryonic development, mechanical forces are essential for cellular rearrangements driving tissue morphogenesis. Here, we show that in the early zebrafish embryo, friction forces are generated at the interface between anterior axial mesoderm (prechordal plate, ppl) progenitors migrating towards the animal pole and neurectoderm progenitors moving in the opposite direction towards the vegetal pole of the embryo. These friction forces lead to global rearrangement of cells within the neurectoderm and determine the position of the neural anlage. Using a combination of experiments and simulations, we show that this process depends on hydrodynamic coupling between neurectoderm and ppl as a result of E-cadherin-mediated adhesion between those tissues. Our data thus establish the emergence of friction forces at the interface between moving tissues as a critical force-generating process shaping the embryo.","lang":"eng"}],"date_updated":"2024-03-25T23:30:21Z","page":"306 - 317","date_created":"2018-12-11T11:47:46Z","volume":19,"status":"public","external_id":{"pmid":["28346437"]},"citation":{"short":"M. Smutny, Z. Ákos, S. Grigolon, S. Shamipour, V. Ruprecht, D. Capek, M. Behrndt, E. Papusheva, M. Tada, B. Hof, T. Vicsek, G. Salbreux, C.-P.J. Heisenberg, Nature Cell Biology 19 (2017) 306–317.","chicago":"Smutny, Michael, Zsuzsa Ákos, Silvia Grigolon, Shayan Shamipour, Verena Ruprecht, Daniel Capek, Martin Behrndt, et al. “Friction Forces Position the Neural Anlage.” <i>Nature Cell Biology</i>. Nature Publishing Group, 2017. <a href=\"https://doi.org/10.1038/ncb3492\">https://doi.org/10.1038/ncb3492</a>.","ieee":"M. Smutny <i>et al.</i>, “Friction forces position the neural anlage,” <i>Nature Cell Biology</i>, vol. 19. Nature Publishing Group, pp. 306–317, 2017.","apa":"Smutny, M., Ákos, Z., Grigolon, S., Shamipour, S., Ruprecht, V., Capek, D., … Heisenberg, C.-P. J. (2017). Friction forces position the neural anlage. <i>Nature Cell Biology</i>. Nature Publishing Group. <a href=\"https://doi.org/10.1038/ncb3492\">https://doi.org/10.1038/ncb3492</a>","ista":"Smutny M, Ákos Z, Grigolon S, Shamipour S, Ruprecht V, Capek D, Behrndt M, Papusheva E, Tada M, Hof B, Vicsek T, Salbreux G, Heisenberg C-PJ. 2017. Friction forces position the neural anlage. Nature Cell Biology. 19, 306–317.","mla":"Smutny, Michael, et al. “Friction Forces Position the Neural Anlage.” <i>Nature Cell Biology</i>, vol. 19, Nature Publishing Group, 2017, pp. 306–17, doi:<a href=\"https://doi.org/10.1038/ncb3492\">10.1038/ncb3492</a>.","ama":"Smutny M, Ákos Z, Grigolon S, et al. Friction forces position the neural anlage. <i>Nature Cell Biology</i>. 2017;19:306-317. doi:<a href=\"https://doi.org/10.1038/ncb3492\">10.1038/ncb3492</a>"},"intvolume":"        19","related_material":{"record":[{"relation":"dissertation_contains","id":"50","status":"public"},{"relation":"dissertation_contains","id":"8350","status":"public"}]},"publication_status":"published","oa":1,"acknowledged_ssus":[{"_id":"SSU"}],"main_file_link":[{"url":"https://europepmc.org/articles/pmc5635970","open_access":"1"}],"date_published":"2017-03-27T00:00:00Z","department":[{"_id":"CaHe"},{"_id":"BjHo"},{"_id":"Bio"}],"pmid":1,"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","publisher":"Nature Publishing Group","ec_funded":1,"scopus_import":1,"publication":"Nature Cell Biology","day":"27","author":[{"full_name":"Smutny, Michael","id":"3FE6E4E8-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-5920-9090","first_name":"Michael","last_name":"Smutny"},{"full_name":"Ákos, Zsuzsa","first_name":"Zsuzsa","last_name":"Ákos"},{"last_name":"Grigolon","first_name":"Silvia","full_name":"Grigolon, Silvia"},{"full_name":"Shamipour, Shayan","id":"40B34FE2-F248-11E8-B48F-1D18A9856A87","last_name":"Shamipour","first_name":"Shayan"},{"full_name":"Ruprecht, Verena","first_name":"Verena","last_name":"Ruprecht"},{"full_name":"Capek, Daniel","id":"31C42484-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-5199-9940","first_name":"Daniel","last_name":"Capek"},{"full_name":"Behrndt, Martin","id":"3ECECA3A-F248-11E8-B48F-1D18A9856A87","last_name":"Behrndt","first_name":"Martin"},{"first_name":"Ekaterina","last_name":"Papusheva","id":"41DB591E-F248-11E8-B48F-1D18A9856A87","full_name":"Papusheva, Ekaterina"},{"full_name":"Tada, Masazumi","first_name":"Masazumi","last_name":"Tada"},{"first_name":"Björn","last_name":"Hof","orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","full_name":"Hof, Björn"},{"first_name":"Tamás","last_name":"Vicsek","full_name":"Vicsek, Tamás"},{"first_name":"Guillaume","last_name":"Salbreux","full_name":"Salbreux, Guillaume"},{"first_name":"Carl-Philipp J","last_name":"Heisenberg","full_name":"Heisenberg, Carl-Philipp J","id":"39427864-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-0912-4566"}],"publist_id":"7074","title":"Friction forces position the neural anlage","project":[{"grant_number":"306589","name":"Decoding the complexity of turbulence at its origin","call_identifier":"FP7","_id":"25152F3A-B435-11E9-9278-68D0E5697425"},{"grant_number":"I 930-B20","_id":"252ABD0A-B435-11E9-9278-68D0E5697425","call_identifier":"FWF","name":"Control of Epithelial Cell Layer Spreading in Zebrafish"}],"language":[{"iso":"eng"}],"publication_identifier":{"issn":["14657392"]},"quality_controlled":"1","doi":"10.1038/ncb3492"},{"status":"public","citation":{"ama":"Lemoult GM, Shi L, Avila K, Jalikop SV, Avila M, Hof B. Directed percolation phase transition to sustained turbulence in Couette flow. <i>Nature Physics</i>. 2016;12(3):254-258. doi:<a href=\"https://doi.org/10.1038/nphys3675\">10.1038/nphys3675</a>","mla":"Lemoult, Grégoire M., et al. “Directed Percolation Phase Transition to Sustained Turbulence in Couette Flow.” <i>Nature Physics</i>, vol. 12, no. 3, Nature Publishing Group, 2016, pp. 254–58, doi:<a href=\"https://doi.org/10.1038/nphys3675\">10.1038/nphys3675</a>.","ista":"Lemoult GM, Shi L, Avila K, Jalikop SV, Avila M, Hof B. 2016. Directed percolation phase transition to sustained turbulence in Couette flow. Nature Physics. 12(3), 254–258.","apa":"Lemoult, G. M., Shi, L., Avila, K., Jalikop, S. V., Avila, M., &#38; Hof, B. (2016). Directed percolation phase transition to sustained turbulence in Couette flow. <i>Nature Physics</i>. Nature Publishing Group. <a href=\"https://doi.org/10.1038/nphys3675\">https://doi.org/10.1038/nphys3675</a>","ieee":"G. M. Lemoult, L. Shi, K. Avila, S. V. Jalikop, M. Avila, and B. Hof, “Directed percolation phase transition to sustained turbulence in Couette flow,” <i>Nature Physics</i>, vol. 12, no. 3. Nature Publishing Group, pp. 254–258, 2016.","chicago":"Lemoult, Grégoire M, Liang Shi, Kerstin Avila, Shreyas V Jalikop, Marc Avila, and Björn Hof. “Directed Percolation Phase Transition to Sustained Turbulence in Couette Flow.” <i>Nature Physics</i>. Nature Publishing Group, 2016. <a href=\"https://doi.org/10.1038/nphys3675\">https://doi.org/10.1038/nphys3675</a>.","short":"G.M. Lemoult, L. Shi, K. Avila, S.V. Jalikop, M. Avila, B. Hof, Nature Physics 12 (2016) 254–258."},"intvolume":"        12","publication_status":"published","date_published":"2016-02-15T00:00:00Z","year":"2016","acknowledgement":"We thank P. Maier for providing valuable ideas and supporting us in the technical aspects. Discussions with D. Barkley, Y. Duguet, B. Eckhart, N. Goldenfeld, P. Manneville and K. Takeuchi are gratefully acknowledged. We acknowledge the Deutsche Forschungsgemeinschaft (Project No. FOR 1182), and the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement 306589 for financial support. L.S. and B.H. acknowledge research funding by Deutsche Forschungsgemeinschaft (DFG) under Grant No. SFB 963/1 (project A8). Numerical simulations were performed thanks to the CPU time allocations of JUROPA in Juelich Supercomputing Center (project HGU17) and of the Max Planck Computing and Data Facility (Garching, Germany). Excellent technical support from M. Rampp on the hybrid code nsCouette is appreciated.","_id":"1494","abstract":[{"lang":"eng","text":"Turbulence is one of the most frequently encountered non-equilibrium phenomena in nature, yet characterizing the transition that gives rise to turbulence in basic shear flows has remained an elusive task. Although, in recent studies, critical points marking the onset of sustained turbulence have been determined for several such flows, the physical nature of the transition could not be fully explained. In extensive experimental and computational studies we show for the example of Couette flow that the onset of turbulence is a second-order phase transition and falls into the directed percolation universality class. Consequently, the complex laminar–turbulent patterns distinctive for the onset of turbulence in shear flows result from short-range interactions of turbulent domains and are characterized by universal critical exponents. More generally, our study demonstrates that even high-dimensional systems far from equilibrium such as turbulence exhibit universality at onset and that here the collective dynamics obeys simple rules."}],"date_updated":"2021-01-12T06:51:08Z","month":"02","oa_version":"None","type":"journal_article","page":"254 - 258","date_created":"2018-12-11T11:52:21Z","volume":12,"project":[{"grant_number":"306589","name":"Decoding the complexity of turbulence at its origin","call_identifier":"FP7","_id":"25152F3A-B435-11E9-9278-68D0E5697425"},{"grant_number":"SFB 963  TP A8","_id":"2511D90C-B435-11E9-9278-68D0E5697425","name":"Astrophysical instability of currents and turbulences"}],"language":[{"iso":"eng"}],"issue":"3","quality_controlled":"1","doi":"10.1038/nphys3675","department":[{"_id":"BjHo"}],"user_id":"3E5EF7F0-F248-11E8-B48F-1D18A9856A87","publisher":"Nature Publishing Group","ec_funded":1,"scopus_import":1,"publication":"Nature Physics","day":"15","author":[{"first_name":"Grégoire M","last_name":"Lemoult","id":"4787FE80-F248-11E8-B48F-1D18A9856A87","full_name":"Lemoult, Grégoire M"},{"id":"374A3F1A-F248-11E8-B48F-1D18A9856A87","full_name":"Shi, Liang","last_name":"Shi","first_name":"Liang"},{"full_name":"Avila, Kerstin","last_name":"Avila","first_name":"Kerstin"},{"id":"44A1D772-F248-11E8-B48F-1D18A9856A87","full_name":"Jalikop, Shreyas V","first_name":"Shreyas V","last_name":"Jalikop"},{"full_name":"Avila, Marc","last_name":"Avila","first_name":"Marc"},{"full_name":"Hof, Björn","orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","last_name":"Hof","first_name":"Björn"}],"publist_id":"5685","title":"Directed percolation phase transition to sustained turbulence in Couette flow"},{"quality_controlled":"1","doi":"10.1038/nature15701","issue":"7574","language":[{"iso":"eng"}],"project":[{"call_identifier":"FP7","_id":"25152F3A-B435-11E9-9278-68D0E5697425","name":"Decoding the complexity of turbulence at its origin","grant_number":"306589"}],"publist_id":"5485","title":"The rise of fully turbulent flow","day":"21","author":[{"full_name":"Barkley, Dwight","last_name":"Barkley","first_name":"Dwight"},{"last_name":"Song","first_name":"Baofang","full_name":"Song, Baofang"},{"full_name":"Vasudevan, Mukund","id":"3C5A959A-F248-11E8-B48F-1D18A9856A87","last_name":"Vasudevan","first_name":"Mukund"},{"last_name":"Lemoult","first_name":"Grégoire M","full_name":"Lemoult, Grégoire M","id":"4787FE80-F248-11E8-B48F-1D18A9856A87"},{"full_name":"Avila, Marc","last_name":"Avila","first_name":"Marc"},{"orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87","full_name":"Hof, Björn","last_name":"Hof","first_name":"Björn"}],"ec_funded":1,"scopus_import":1,"publication":"Nature","department":[{"_id":"BjHo"}],"publisher":"Nature Publishing Group","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","main_file_link":[{"url":"http://arxiv.org/abs/1510.09143","open_access":"1"}],"date_published":"2015-10-21T00:00:00Z","oa":1,"publication_status":"published","citation":{"short":"D. Barkley, B. Song, M. Vasudevan, G.M. Lemoult, M. Avila, B. Hof, Nature 526 (2015) 550–553.","ieee":"D. Barkley, B. Song, M. Vasudevan, G. M. Lemoult, M. Avila, and B. Hof, “The rise of fully turbulent flow,” <i>Nature</i>, vol. 526, no. 7574. Nature Publishing Group, pp. 550–553, 2015.","chicago":"Barkley, Dwight, Baofang Song, Mukund Vasudevan, Grégoire M Lemoult, Marc Avila, and Björn Hof. “The Rise of Fully Turbulent Flow.” <i>Nature</i>. Nature Publishing Group, 2015. <a href=\"https://doi.org/10.1038/nature15701\">https://doi.org/10.1038/nature15701</a>.","ista":"Barkley D, Song B, Vasudevan M, Lemoult GM, Avila M, Hof B. 2015. The rise of fully turbulent flow. Nature. 526(7574), 550–553.","mla":"Barkley, Dwight, et al. “The Rise of Fully Turbulent Flow.” <i>Nature</i>, vol. 526, no. 7574, Nature Publishing Group, 2015, pp. 550–53, doi:<a href=\"https://doi.org/10.1038/nature15701\">10.1038/nature15701</a>.","apa":"Barkley, D., Song, B., Vasudevan, M., Lemoult, G. M., Avila, M., &#38; Hof, B. (2015). The rise of fully turbulent flow. <i>Nature</i>. Nature Publishing Group. <a href=\"https://doi.org/10.1038/nature15701\">https://doi.org/10.1038/nature15701</a>","ama":"Barkley D, Song B, Vasudevan M, Lemoult GM, Avila M, Hof B. The rise of fully turbulent flow. <i>Nature</i>. 2015;526(7574):550-553. doi:<a href=\"https://doi.org/10.1038/nature15701\">10.1038/nature15701</a>"},"intvolume":"       526","status":"public","date_created":"2018-12-11T11:53:20Z","volume":526,"month":"10","oa_version":"Preprint","type":"journal_article","abstract":[{"text":"Over a century of research into the origin of turbulence in wall-bounded shear flows has resulted in a puzzling picture in which turbulence appears in a variety of different states competing with laminar background flow. At moderate flow speeds, turbulence is confined to localized patches; it is only at higher speeds that the entire flow becomes turbulent. The origin of the different states encountered during this transition, the front dynamics of the turbulent regions and the transformation to full turbulence have yet to be explained. By combining experiments, theory and computer simulations, here we uncover a bifurcation scenario that explains the transformation to fully turbulent pipe flow and describe the front dynamics of the different states encountered in the process. Key to resolving this problem is the interpretation of the flow as a bistable system with nonlinear propagation (advection) of turbulent fronts. These findings bridge the gap between our understanding of the onset of turbulence and fully turbulent flows.","lang":"eng"}],"date_updated":"2021-01-12T06:52:22Z","page":"550 - 553","_id":"1664","year":"2015","acknowledgement":"We acknowledge the Deutsche Forschungsgemeinschaft (Project No. FOR 1182), and the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement 306589 for financial support. B.S. acknowledges financial support from the Chinese State Scholarship Fund under grant number 2010629145. B.S. acknowledges support from the International Max Planck Research School for the Physics of Biological and Complex Systems and the Göttingen Graduate School for Neurosciences and Molecular Biosciences. We acknowledge computing resources from GWDG (Gesellschaft für wissenschaftliche Datenverarbeitung Göttingen) and the Jülich Supercomputing Centre (grant HGU16) where the simulations were performed."},{"abstract":[{"lang":"eng","text":"Transition to turbulence in straight pipes occurs in spite of the linear stability of the laminar Hagen-Poiseuille flow if both the amplitude of flow perturbations and the Reynolds number Re exceed a minimum threshold (subcritical transition). As the pipe curvature increases, centrifugal effects become important, modifying the basic flow as well as the most unstable linear modes. If the curvature (tube-to-coiling diameter d/D) is sufficiently large, a Hopf bifurcation (supercritical instability) is encountered before turbulence can be excited (subcritical instability). We trace the instability thresholds in the Re - d/D parameter space in the range 0.01 ≤ d/D\\ ≤ 0.1 by means of laser-Doppler velocimetry and determine the point where the subcritical and supercritical instabilities meet. Two different experimental set-ups are used: a closed system where the pipe forms an axisymmetric torus and an open system employing a helical pipe. Implications for the measurement of friction factors in curved pipes are discussed."}],"date_updated":"2021-01-12T06:53:31Z","month":"04","oa_version":"Preprint","type":"journal_article","volume":770,"date_created":"2018-12-11T11:54:17Z","year":"2015","_id":"1837","oa":1,"publication_status":"published","date_published":"2015-04-08T00:00:00Z","main_file_link":[{"url":"https://arxiv.org/abs/1508.06559","open_access":"1"}],"status":"public","external_id":{"arxiv":["1508.06559"]},"intvolume":"       770","citation":{"ieee":"J. Kühnen, P. Braunshier, M. Schwegel, H. Kuhlmann, and B. Hof, “Subcritical versus supercritical transition to turbulence in curved pipes,” <i>Journal of Fluid Mechanics</i>, vol. 770, no. 5. Cambridge University Press, 2015.","chicago":"Kühnen, Jakob, P Braunshier, M Schwegel, Hendrik Kuhlmann, and Björn Hof. “Subcritical versus Supercritical Transition to Turbulence in Curved Pipes.” <i>Journal of Fluid Mechanics</i>. Cambridge University Press, 2015. <a href=\"https://doi.org/10.1017/jfm.2015.184\">https://doi.org/10.1017/jfm.2015.184</a>.","short":"J. Kühnen, P. Braunshier, M. Schwegel, H. Kuhlmann, B. Hof, Journal of Fluid Mechanics 770 (2015).","ama":"Kühnen J, Braunshier P, Schwegel M, Kuhlmann H, Hof B. Subcritical versus supercritical transition to turbulence in curved pipes. <i>Journal of Fluid Mechanics</i>. 2015;770(5). doi:<a href=\"https://doi.org/10.1017/jfm.2015.184\">10.1017/jfm.2015.184</a>","mla":"Kühnen, Jakob, et al. “Subcritical versus Supercritical Transition to Turbulence in Curved Pipes.” <i>Journal of Fluid Mechanics</i>, vol. 770, no. 5, R3, Cambridge University Press, 2015, doi:<a href=\"https://doi.org/10.1017/jfm.2015.184\">10.1017/jfm.2015.184</a>.","ista":"Kühnen J, Braunshier P, Schwegel M, Kuhlmann H, Hof B. 2015. Subcritical versus supercritical transition to turbulence in curved pipes. Journal of Fluid Mechanics. 770(5), R3.","apa":"Kühnen, J., Braunshier, P., Schwegel, M., Kuhlmann, H., &#38; Hof, B. (2015). Subcritical versus supercritical transition to turbulence in curved pipes. <i>Journal of Fluid Mechanics</i>. Cambridge University Press. <a href=\"https://doi.org/10.1017/jfm.2015.184\">https://doi.org/10.1017/jfm.2015.184</a>"},"author":[{"last_name":"Kühnen","first_name":"Jakob","orcid":"0000-0003-4312-0179","id":"3A47AE32-F248-11E8-B48F-1D18A9856A87","full_name":"Kühnen, Jakob"},{"last_name":"Braunshier","first_name":"P","full_name":"Braunshier, P"},{"full_name":"Schwegel, M","first_name":"M","last_name":"Schwegel"},{"last_name":"Kuhlmann","first_name":"Hendrik","full_name":"Kuhlmann, Hendrik"},{"last_name":"Hof","first_name":"Björn","id":"3A374330-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-2057-2754","full_name":"Hof, Björn"}],"day":"08","title":"Subcritical versus supercritical transition to turbulence in curved pipes","arxiv":1,"article_number":"R3","publist_id":"5265","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","publisher":"Cambridge University Press","department":[{"_id":"BjHo"}],"publication":"Journal of Fluid Mechanics","article_processing_charge":"No","scopus_import":1,"ec_funded":1,"article_type":"original","doi":"10.1017/jfm.2015.184","quality_controlled":"1","project":[{"name":"Decoding the complexity of turbulence at its origin","call_identifier":"FP7","_id":"25152F3A-B435-11E9-9278-68D0E5697425","grant_number":"306589"}],"language":[{"iso":"eng"}],"issue":"5"},{"oa_version":"Preprint","type":"journal_article","month":"06","abstract":[{"text":"In pipe, channel, and boundary layer flows turbulence first occurs intermittently in space and time: at moderate Reynolds numbers domains of disordered turbulent motion are separated by quiescent laminar regions. Based on direct numerical simulations of pipe flow we argue here that the spatial intermittency has its origin in a nearest neighbor interaction between turbulent regions. We further show that in this regime turbulent flows are intrinsically intermittent with a well-defined equilibrium turbulent fraction but without ever assuming a steady pattern. This transition scenario is analogous to that found in simple models such as coupled map lattices. The scaling observed implies that laminar intermissions of the turbulent flow will persist to arbitrarily large Reynolds numbers.","lang":"eng"}],"date_updated":"2021-01-12T06:59:53Z","date_created":"2018-12-11T11:59:43Z","volume":87,"year":"2013","_id":"2811","publication_status":"published","oa":1,"main_file_link":[{"url":"http://arxiv.org/abs/1306.5890","open_access":"1"}],"date_published":"2013-06-18T00:00:00Z","external_id":{"arxiv":["1306.5890"]},"status":"public","citation":{"ama":"Avila M, Hof B. Nature of laminar-turbulence intermittency in shear flows. <i>Physical Review E</i>. 2013;87(6). doi:<a href=\"https://doi.org/10.1103/PhysRevE.87.063012\">10.1103/PhysRevE.87.063012</a>","apa":"Avila, M., &#38; Hof, B. (2013). Nature of laminar-turbulence intermittency in shear flows. <i>Physical Review E</i>. American Institute of Physics. <a href=\"https://doi.org/10.1103/PhysRevE.87.063012\">https://doi.org/10.1103/PhysRevE.87.063012</a>","ista":"Avila M, Hof B. 2013. Nature of laminar-turbulence intermittency in shear flows. Physical Review E. 87(6), 063012.","mla":"Avila, Marc, and Björn Hof. “Nature of Laminar-Turbulence Intermittency in Shear Flows.” <i>Physical Review E</i>, vol. 87, no. 6, 063012, American Institute of Physics, 2013, doi:<a href=\"https://doi.org/10.1103/PhysRevE.87.063012\">10.1103/PhysRevE.87.063012</a>.","chicago":"Avila, Marc, and Björn Hof. “Nature of Laminar-Turbulence Intermittency in Shear Flows.” <i>Physical Review E</i>. American Institute of Physics, 2013. <a href=\"https://doi.org/10.1103/PhysRevE.87.063012\">https://doi.org/10.1103/PhysRevE.87.063012</a>.","ieee":"M. Avila and B. Hof, “Nature of laminar-turbulence intermittency in shear flows,” <i>Physical Review E</i>, vol. 87, no. 6. American Institute of Physics, 2013.","short":"M. Avila, B. Hof, Physical Review E 87 (2013)."},"intvolume":"        87","day":"18","author":[{"full_name":"Avila, Marc","first_name":"Marc","last_name":"Avila"},{"first_name":"Björn","last_name":"Hof","full_name":"Hof, Björn","orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87"}],"publist_id":"4074","article_number":"063012","arxiv":1,"title":"Nature of laminar-turbulence intermittency in shear flows","department":[{"_id":"BjHo"}],"publisher":"American Institute of Physics","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","ec_funded":1,"scopus_import":1,"publication":"Physical Review E","quality_controlled":"1","doi":"10.1103/PhysRevE.87.063012","project":[{"name":"Decoding the complexity of turbulence at its origin","call_identifier":"FP7","_id":"25152F3A-B435-11E9-9278-68D0E5697425","grant_number":"306589"}],"issue":"6","language":[{"iso":"eng"}]},{"_id":"2829","year":"2013","volume":110,"date_created":"2018-12-11T11:59:49Z","abstract":[{"lang":"eng","text":"Laminar-turbulent intermittency is intrinsic to the transitional regime of a wide range of fluid flows including pipe, channel, boundary layer, and Couette flow. In the latter turbulent spots can grow and form continuous stripes, yet in the stripe-normal direction they remain interspersed by laminar fluid. We carry out direct numerical simulations in a long narrow domain and observe that individual turbulent stripes are transient. In agreement with recent observations in pipe flow, we find that turbulence becomes sustained at a distinct critical point once the spatial proliferation outweighs the inherent decaying process. By resolving the asymptotic size distributions close to criticality we can for the first time demonstrate scale invariance at the onset of turbulence."}],"date_updated":"2021-01-12T07:00:00Z","month":"05","oa_version":"Preprint","type":"journal_article","intvolume":"       110","citation":{"short":"L. Shi, M. Avila, B. Hof, Physical Review Letters 110 (2013).","ieee":"L. Shi, M. Avila, and B. Hof, “Scale invariance at the onset of turbulence in couette flow,” <i>Physical Review Letters</i>, vol. 110, no. 20. American Physical Society, 2013.","chicago":"Shi, Liang, Marc Avila, and Björn Hof. “Scale Invariance at the Onset of Turbulence in Couette Flow.” <i>Physical Review Letters</i>. American Physical Society, 2013. <a href=\"https://doi.org/10.1103/PhysRevLett.110.204502\">https://doi.org/10.1103/PhysRevLett.110.204502</a>.","mla":"Shi, Liang, et al. “Scale Invariance at the Onset of Turbulence in Couette Flow.” <i>Physical Review Letters</i>, vol. 110, no. 20, 204502, American Physical Society, 2013, doi:<a href=\"https://doi.org/10.1103/PhysRevLett.110.204502\">10.1103/PhysRevLett.110.204502</a>.","ista":"Shi L, Avila M, Hof B. 2013. Scale invariance at the onset of turbulence in couette flow. Physical Review Letters. 110(20), 204502.","apa":"Shi, L., Avila, M., &#38; Hof, B. (2013). Scale invariance at the onset of turbulence in couette flow. <i>Physical Review Letters</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevLett.110.204502\">https://doi.org/10.1103/PhysRevLett.110.204502</a>","ama":"Shi L, Avila M, Hof B. Scale invariance at the onset of turbulence in couette flow. <i>Physical Review Letters</i>. 2013;110(20). doi:<a href=\"https://doi.org/10.1103/PhysRevLett.110.204502\">10.1103/PhysRevLett.110.204502</a>"},"status":"public","external_id":{"arxiv":["1304.5446"]},"date_published":"2013-05-13T00:00:00Z","main_file_link":[{"url":"http://arxiv.org/abs/1304.5446","open_access":"1"}],"oa":1,"publication_status":"published","publication":"Physical Review Letters","scopus_import":1,"ec_funded":1,"publisher":"American Physical Society","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","department":[{"_id":"BjHo"}],"arxiv":1,"title":"Scale invariance at the onset of turbulence in couette flow","article_number":"204502","publist_id":"3970","author":[{"id":"374A3F1A-F248-11E8-B48F-1D18A9856A87","full_name":"Shi, Liang","first_name":"Liang","last_name":"Shi"},{"full_name":"Avila, Marc","first_name":"Marc","last_name":"Avila"},{"full_name":"Hof, Björn","id":"3A374330-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-2057-2754","last_name":"Hof","first_name":"Björn"}],"day":"13","language":[{"iso":"eng"}],"issue":"20","project":[{"grant_number":"306589","name":"Decoding the complexity of turbulence at its origin","call_identifier":"FP7","_id":"25152F3A-B435-11E9-9278-68D0E5697425"},{"grant_number":"SFB 963  TP A8","_id":"2511D90C-B435-11E9-9278-68D0E5697425","name":"Astrophysical instability of currents and turbulences"}],"doi":"10.1103/PhysRevLett.110.204502","quality_controlled":"1"},{"day":"29","author":[{"full_name":"Avila, Marc","last_name":"Avila","first_name":"Marc"},{"full_name":"Mellibovsky, Fernando","last_name":"Mellibovsky","first_name":"Fernando"},{"first_name":"Nicolas","last_name":"Roland","full_name":"Roland, Nicolas"},{"last_name":"Hof","first_name":"Björn","full_name":"Hof, Björn","orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87"}],"publist_id":"3965","article_number":"224502","arxiv":1,"title":"Streamwise-localized solutions at the onset of turbulence in pipe flow","department":[{"_id":"BjHo"}],"publisher":"American Physical Society","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","ec_funded":1,"scopus_import":1,"publication":"Physical Review Letters","quality_controlled":"1","doi":"10.1103/PhysRevLett.110.224502","project":[{"call_identifier":"FP7","_id":"25152F3A-B435-11E9-9278-68D0E5697425","name":"Decoding the complexity of turbulence at its origin","grant_number":"306589"}],"issue":"22","language":[{"iso":"eng"}],"month":"05","type":"journal_article","oa_version":"Preprint","abstract":[{"lang":"eng","text":"Although the equations governing fluid flow are well known, there are no analytical expressions that describe the complexity of turbulent motion. A recent proposition is that in analogy to low dimensional chaotic systems, turbulence is organized around unstable solutions of the governing equations which provide the building blocks of the disordered dynamics. We report the discovery of periodic solutions which just like intermittent turbulence are spatially localized and show that turbulent transients arise from one such solution branch."}],"date_updated":"2021-01-12T07:00:05Z","date_created":"2018-12-11T11:59:50Z","volume":110,"year":"2013","_id":"2834","oa":1,"publication_status":"published","main_file_link":[{"url":"http://arxiv.org/abs/1212.0230","open_access":"1"}],"date_published":"2013-05-29T00:00:00Z","external_id":{"arxiv":["1212.0230"]},"status":"public","citation":{"short":"M. Avila, F. Mellibovsky, N. Roland, B. Hof, Physical Review Letters 110 (2013).","ieee":"M. Avila, F. Mellibovsky, N. Roland, and B. Hof, “Streamwise-localized solutions at the onset of turbulence in pipe flow,” <i>Physical Review Letters</i>, vol. 110, no. 22. American Physical Society, 2013.","chicago":"Avila, Marc, Fernando Mellibovsky, Nicolas Roland, and Björn Hof. “Streamwise-Localized Solutions at the Onset of Turbulence in Pipe Flow.” <i>Physical Review Letters</i>. American Physical Society, 2013. <a href=\"https://doi.org/10.1103/PhysRevLett.110.224502\">https://doi.org/10.1103/PhysRevLett.110.224502</a>.","mla":"Avila, Marc, et al. “Streamwise-Localized Solutions at the Onset of Turbulence in Pipe Flow.” <i>Physical Review Letters</i>, vol. 110, no. 22, 224502, American Physical Society, 2013, doi:<a href=\"https://doi.org/10.1103/PhysRevLett.110.224502\">10.1103/PhysRevLett.110.224502</a>.","ista":"Avila M, Mellibovsky F, Roland N, Hof B. 2013. Streamwise-localized solutions at the onset of turbulence in pipe flow. Physical Review Letters. 110(22), 224502.","apa":"Avila, M., Mellibovsky, F., Roland, N., &#38; Hof, B. (2013). Streamwise-localized solutions at the onset of turbulence in pipe flow. <i>Physical Review Letters</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevLett.110.224502\">https://doi.org/10.1103/PhysRevLett.110.224502</a>","ama":"Avila M, Mellibovsky F, Roland N, Hof B. Streamwise-localized solutions at the onset of turbulence in pipe flow. <i>Physical Review Letters</i>. 2013;110(22). doi:<a href=\"https://doi.org/10.1103/PhysRevLett.110.224502\">10.1103/PhysRevLett.110.224502</a>"},"intvolume":"       110"}]