[{"oa_version":"Published Version","quality_controlled":"1","user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","acknowledgement":"The anonymous referees are kindly acknowledged for their useful suggestions andcomments.","publication_identifier":{"eissn":["14697645"],"issn":["00221120"]},"_id":"9467","article_processing_charge":"Yes (via OA deal)","date_updated":"2023-08-08T13:58:41Z","volume":919,"oa":1,"arxiv":1,"author":[{"id":"0BE7553A-1004-11EA-B805-18983DDC885E","last_name":"Marensi","full_name":"Marensi, Elena","first_name":"Elena"},{"first_name":"Shuisheng","full_name":"He, Shuisheng","last_name":"He"},{"first_name":"Ashley P.","full_name":"Willis, Ashley P.","last_name":"Willis"}],"abstract":[{"text":"Turbulence in the flow of fluid through a pipe can be suppressed by buoyancy forces. As the suppression of turbulence leads to severe heat transfer deterioration, this is an important and undesirable phenomenon in both heating and cooling applications. Vertical flow is often considered, as the axial buoyancy force can help drive the flow. With heating measured by the buoyancy parameter 𝐶, our direct numerical simulations show that shear-driven turbulence may either be completely laminarised or it transitions to a relatively quiescent convection-driven state. Buoyancy forces cause a flattening of the base flow profile, which in isothermal pipe flow has recently been linked to complete suppression of turbulence (Kühnen et al., Nat. Phys., vol. 14, 2018, pp. 386–390), and the flattened laminar base profile has enhanced nonlinear stability (Marensi et al., J. Fluid Mech., vol. 863, 2019, pp. 50–875). In agreement with these findings, the nonlinear lower-branch travelling-wave solution analysed here, which is believed to mediate transition to turbulence in isothermal pipe flow, is shown to be suppressed by buoyancy. A linear instability of the laminar base flow is responsible for the appearance of the relatively quiescent convection driven state for 𝐶≳4 across the range of Reynolds numbers considered. In the suppression of turbulence, however, i.e. in the transition from turbulence, we find clearer association with the analysis of He et al. (J. Fluid Mech., vol. 809, 2016, pp. 31–71) than with the above dynamical systems approach, which describes better the transition to turbulence. The laminarisation criterion He et al. propose, based on an apparent Reynolds number of the flow as measured by its driving pressure gradient, is found to capture the critical 𝐶=𝐶𝑐𝑟(𝑅𝑒) above which the flow will be laminarised or switch to the convection-driven type. Our analysis suggests that it is the weakened rolls, rather than the streaks, which appear to be critical for laminarisation.","lang":"eng"}],"citation":{"chicago":"Marensi, Elena, Shuisheng He, and Ashley P. Willis. “Suppression of Turbulence and Travelling Waves in a Vertical Heated Pipe.” <i>Journal of Fluid Mechanics</i>. Cambridge University Press, 2021. <a href=\"https://doi.org/10.1017/jfm.2021.371\">https://doi.org/10.1017/jfm.2021.371</a>.","apa":"Marensi, E., He, S., &#38; Willis, A. P. (2021). Suppression of turbulence and travelling waves in a vertical heated pipe. <i>Journal of Fluid Mechanics</i>. Cambridge University Press. <a href=\"https://doi.org/10.1017/jfm.2021.371\">https://doi.org/10.1017/jfm.2021.371</a>","ieee":"E. Marensi, S. He, and A. P. Willis, “Suppression of turbulence and travelling waves in a vertical heated pipe,” <i>Journal of Fluid Mechanics</i>, vol. 919. Cambridge University Press, 2021.","short":"E. Marensi, S. He, A.P. Willis, Journal of Fluid Mechanics 919 (2021).","ista":"Marensi E, He S, Willis AP. 2021. Suppression of turbulence and travelling waves in a vertical heated pipe. Journal of Fluid Mechanics. 919, A17.","mla":"Marensi, Elena, et al. “Suppression of Turbulence and Travelling Waves in a Vertical Heated Pipe.” <i>Journal of Fluid Mechanics</i>, vol. 919, A17, Cambridge University Press, 2021, doi:<a href=\"https://doi.org/10.1017/jfm.2021.371\">10.1017/jfm.2021.371</a>.","ama":"Marensi E, He S, Willis AP. Suppression of turbulence and travelling waves in a vertical heated pipe. <i>Journal of Fluid Mechanics</i>. 2021;919. doi:<a href=\"https://doi.org/10.1017/jfm.2021.371\">10.1017/jfm.2021.371</a>"},"publication_status":"published","ddc":["530"],"isi":1,"article_number":"A17","tmp":{"image":"/images/cc_by.png","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"title":"Suppression of turbulence and travelling waves in a vertical heated pipe","external_id":{"arxiv":["2008.13486"],"isi":["000653785000001"]},"year":"2021","doi":"10.1017/jfm.2021.371","file_date_updated":"2021-08-03T09:53:28Z","publication":"Journal of Fluid Mechanics","status":"public","intvolume":"       919","type":"journal_article","day":"25","date_created":"2021-06-06T22:01:30Z","file":[{"content_type":"application/pdf","relation":"main_file","file_id":"9766","creator":"kschuh","success":1,"date_updated":"2021-08-03T09:53:28Z","access_level":"open_access","file_name":"2021_JournalFluidMechanics_Marensi.pdf","file_size":4087358,"date_created":"2021-08-03T09:53:28Z","checksum":"867ad077e45c181c2c5ec1311ba27c41"}],"department":[{"_id":"BjHo"}],"has_accepted_license":"1","language":[{"iso":"eng"}],"scopus_import":"1","publisher":"Cambridge University Press","date_published":"2021-07-25T00:00:00Z","article_type":"original","month":"07"},{"file":[{"content_type":"application/pdf","relation":"main_file","file_id":"8070","creator":"cziletti","file_name":"2020_JournalOfFluidMech_Paranjape.pdf","file_size":767873,"date_created":"2020-06-30T08:37:37Z","checksum":"3f487bf6d9286787096306eaa18702e8","date_updated":"2020-07-14T12:48:08Z","access_level":"open_access"}],"date_created":"2020-06-29T07:59:35Z","department":[{"_id":"BjHo"}],"has_accepted_license":"1","license":"https://creativecommons.org/licenses/by-nc-sa/4.0/","language":[{"iso":"eng"}],"scopus_import":"1","publisher":"Cambridge University Press","date_published":"2020-08-25T00:00:00Z","article_type":"original","month":"08","file_date_updated":"2020-07-14T12:48:08Z","publication":"Journal of Fluid Mechanics","status":"public","intvolume":"       897","type":"journal_article","day":"25","ddc":["530"],"article_number":"A7","isi":1,"tmp":{"short":"CC BY-NC-SA (4.0)","name":"Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)","image":"/images/cc_by_nc_sa.png","legal_code_url":"https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode"},"external_id":{"isi":["000539132300001"]},"title":"Oblique stripe solutions of channel flow","year":"2020","doi":"10.1017/jfm.2020.322","oa_version":"Published Version","quality_controlled":"1","acknowledgement":"The authors thank S. Zammert and B. Budanur for useful discussions. J. F. Gibson is gratefully acknowledged for the development and the maintenance of the code Channelflow. Y.D. would like to thank P. Schlatter and D. S. Henningson for an early collaboration on a similar topic in the case of plane Couette flow during the years 2008–2013.","user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","publication_identifier":{"eissn":["14697645"],"issn":["00221120"]},"_id":"8043","article_processing_charge":"Yes (via OA deal)","date_updated":"2023-08-22T07:48:02Z","volume":897,"oa":1,"author":[{"first_name":"Chaitanya S","full_name":"Paranjape, Chaitanya S","last_name":"Paranjape","id":"3D85B7C4-F248-11E8-B48F-1D18A9856A87"},{"full_name":"Duguet, Yohann","last_name":"Duguet","first_name":"Yohann"},{"id":"3A374330-F248-11E8-B48F-1D18A9856A87","full_name":"Hof, Björn","last_name":"Hof","orcid":"0000-0003-2057-2754","first_name":"Björn"}],"abstract":[{"text":"With decreasing Reynolds number, Re, turbulence in channel flow becomes spatio-temporally intermittent and self-organises into solitary stripes oblique to the mean flow direction. We report here the existence of localised nonlinear travelling wave solutions of the Navier–Stokes equations possessing this obliqueness property. Such solutions are identified numerically using edge tracking coupled with arclength continuation. All solutions emerge in saddle-node bifurcations at values of Re lower than the non-localised solutions. Relative periodic orbit solutions bifurcating from branches of travelling waves have also been computed. A complete parametric study is performed, including their stability, the investigation of their large-scale flow, and the robustness to changes of the numerical domain.","lang":"eng"}],"citation":{"ama":"Paranjape CS, Duguet Y, Hof B. Oblique stripe solutions of channel flow. <i>Journal of Fluid Mechanics</i>. 2020;897. doi:<a href=\"https://doi.org/10.1017/jfm.2020.322\">10.1017/jfm.2020.322</a>","mla":"Paranjape, Chaitanya S., et al. “Oblique Stripe Solutions of Channel Flow.” <i>Journal of Fluid Mechanics</i>, vol. 897, A7, Cambridge University Press, 2020, doi:<a href=\"https://doi.org/10.1017/jfm.2020.322\">10.1017/jfm.2020.322</a>.","short":"C.S. Paranjape, Y. Duguet, B. Hof, Journal of Fluid Mechanics 897 (2020).","ista":"Paranjape CS, Duguet Y, Hof B. 2020. Oblique stripe solutions of channel flow. Journal of Fluid Mechanics. 897, A7.","ieee":"C. S. Paranjape, Y. Duguet, and B. Hof, “Oblique stripe solutions of channel flow,” <i>Journal of Fluid Mechanics</i>, vol. 897. Cambridge University Press, 2020.","apa":"Paranjape, C. S., Duguet, Y., &#38; Hof, B. (2020). Oblique stripe solutions of channel flow. <i>Journal of Fluid Mechanics</i>. Cambridge University Press. <a href=\"https://doi.org/10.1017/jfm.2020.322\">https://doi.org/10.1017/jfm.2020.322</a>","chicago":"Paranjape, Chaitanya S, Yohann Duguet, and Björn Hof. “Oblique Stripe Solutions of Channel Flow.” <i>Journal of Fluid Mechanics</i>. Cambridge University Press, 2020. <a href=\"https://doi.org/10.1017/jfm.2020.322\">https://doi.org/10.1017/jfm.2020.322</a>."},"publication_status":"published"},{"publication":"Journal of Fluid Mechanics","page":"934-948","intvolume":"       867","status":"public","day":"25","type":"journal_article","date_created":"2019-04-07T21:59:14Z","department":[{"_id":"BjHo"}],"publisher":"Cambridge University Press","scopus_import":"1","language":[{"iso":"eng"}],"month":"05","date_published":"2019-05-25T00:00:00Z","_id":"6228","publication_identifier":{"eissn":["14697645"],"issn":["00221120"]},"user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","quality_controlled":"1","oa_version":"Preprint","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","call_identifier":"H2020","_id":"25104D44-B435-11E9-9278-68D0E5697425","name":"Eliminating turbulence in oil pipelines"}],"arxiv":1,"oa":1,"date_updated":"2024-03-25T23:30:20Z","volume":867,"article_processing_charge":"No","abstract":[{"lang":"eng","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."}],"author":[{"last_name":"Scarselli","full_name":"Scarselli, Davide","orcid":"0000-0001-5227-4271","first_name":"Davide","id":"40315C30-F248-11E8-B48F-1D18A9856A87"},{"first_name":"Jakob","last_name":"Kühnen","full_name":"Kühnen, Jakob","orcid":"0000-0003-4312-0179","id":"3A47AE32-F248-11E8-B48F-1D18A9856A87"},{"id":"3A374330-F248-11E8-B48F-1D18A9856A87","first_name":"Björn","orcid":"0000-0003-2057-2754","full_name":"Hof, Björn","last_name":"Hof"}],"publication_status":"published","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>.","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>","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.","ista":"Scarselli D, Kühnen J, Hof B. 2019. Relaminarising pipe flow by wall movement. Journal of Fluid Mechanics. 867, 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>","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>."},"related_material":{"link":[{"url":"https://doi.org/10.1017/jfm.2019.191","relation":"supplementary_material"}],"record":[{"status":"public","relation":"dissertation_contains","id":"7258"}]},"main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1807.05357"}],"isi":1,"external_id":{"arxiv":["1807.05357"],"isi":["000462606100001"]},"title":"Relaminarising pipe flow by wall movement","year":"2019","doi":"10.1017/jfm.2019.191","ec_funded":1},{"intvolume":"       813","status":"public","day":"25","type":"journal_article","publication":"Journal of Fluid Mechanics","page":"1045 - 1059","scopus_import":"1","publisher":"Cambridge University Press","language":[{"iso":"eng"}],"month":"02","date_published":"2017-02-25T00:00:00Z","date_created":"2018-12-11T11:50:04Z","department":[{"_id":"BjHo"}],"abstract":[{"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.","lang":"eng"}],"author":[{"full_name":"Song, Baofang","last_name":"Song","first_name":"Baofang"},{"last_name":"Barkley","full_name":"Barkley, Dwight","first_name":"Dwight"},{"orcid":"0000-0003-2057-2754","last_name":"Hof","full_name":"Hof, Björn","first_name":"Björn","id":"3A374330-F248-11E8-B48F-1D18A9856A87"},{"last_name":"Avila","full_name":"Avila, Marc","first_name":"Marc"}],"citation":{"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.","short":"B. Song, D. Barkley, B. Hof, M. Avila, Journal of Fluid Mechanics 813 (2017) 1045–1059.","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>.","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>","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>.","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>","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."},"publication_status":"published","publication_identifier":{"issn":["00221120"]},"_id":"1087","oa_version":"Submitted Version","project":[{"_id":"25152F3A-B435-11E9-9278-68D0E5697425","name":"Decoding the complexity of turbulence at its origin","call_identifier":"FP7","grant_number":"306589"}],"quality_controlled":"1","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","article_processing_charge":"No","publist_id":"6290","volume":813,"date_updated":"2023-09-20T11:47:22Z","oa":1,"title":"Speed and structure of turbulent fronts in pipe flow","external_id":{"isi":["000394376400044"]},"year":"2017","doi":"10.1017/jfm.2017.14","acknowledged_ssus":[{"_id":"ScienComp"}],"ec_funded":1,"isi":1,"main_file_link":[{"url":"https://arxiv.org/abs/1603.04077","open_access":"1"}]},{"page":"274 - 301","publication":"Journal of Fluid Mechanics","status":"public","intvolume":"       833","type":"journal_article","day":"25","date_created":"2018-12-11T11:48:32Z","department":[{"_id":"BjHo"}],"language":[{"iso":"eng"}],"scopus_import":"1","publisher":"Cambridge University Press","date_published":"2017-12-25T00:00:00Z","month":"12","quality_controlled":"1","project":[{"grant_number":"11-NSF-1070","_id":"25636330-B435-11E9-9278-68D0E5697425","name":"ROOTS Genome-wide Analysis of Root Traits"}],"oa_version":"Submitted Version","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","publication_identifier":{"issn":["00221120"]},"_id":"792","article_processing_charge":"No","publist_id":"6862","volume":833,"date_updated":"2023-09-27T12:17:35Z","oa":1,"author":[{"id":"3EA1010E-F248-11E8-B48F-1D18A9856A87","first_name":"Nazmi B","orcid":"0000-0003-0423-5010","full_name":"Budanur, Nazmi B","last_name":"Budanur"},{"first_name":"Kimberly","full_name":"Short, Kimberly","last_name":"Short"},{"first_name":"Mohammad","last_name":"Farazmand","full_name":"Farazmand, Mohammad"},{"first_name":"Ashley","full_name":"Willis, Ashley","last_name":"Willis"},{"full_name":"Cvitanović, Predrag","last_name":"Cvitanović","first_name":"Predrag"}],"abstract":[{"text":"The chaotic dynamics of low-dimensional systems, such as Lorenz or Rössler flows, is guided by the infinity of periodic orbits embedded in their strange attractors. Whether this is also the case for the infinite-dimensional dynamics of Navier–Stokes equations has long been speculated, and is a topic of ongoing study. Periodic and relative periodic solutions have been shown to be involved in transitions to turbulence. Their relevance to turbulent dynamics – specifically, whether periodic orbits play the same role in high-dimensional nonlinear systems like the Navier–Stokes equations as they do in lower-dimensional systems – is the focus of the present investigation. We perform here a detailed study of pipe flow relative periodic orbits with energies and mean dissipations close to turbulent values. We outline several approaches to reduction of the translational symmetry of the system. We study pipe flow in a minimal computational cell at   Re=2500, and report a library of invariant solutions found with the aid of the method of slices. Detailed study of the unstable manifolds of a sample of these solutions is consistent with the picture that relative periodic orbits are embedded in the chaotic saddle and that they guide the turbulent dynamics.","lang":"eng"}],"citation":{"ama":"Budanur NB, Short K, Farazmand M, Willis A, Cvitanović P. Relative periodic orbits form the backbone of turbulent pipe flow. <i>Journal of Fluid Mechanics</i>. 2017;833:274-301. doi:<a href=\"https://doi.org/10.1017/jfm.2017.699\">10.1017/jfm.2017.699</a>","mla":"Budanur, Nazmi B., et al. “Relative Periodic Orbits Form the Backbone of Turbulent Pipe Flow.” <i>Journal of Fluid Mechanics</i>, vol. 833, Cambridge University Press, 2017, pp. 274–301, doi:<a href=\"https://doi.org/10.1017/jfm.2017.699\">10.1017/jfm.2017.699</a>.","ista":"Budanur NB, Short K, Farazmand M, Willis A, Cvitanović P. 2017. Relative periodic orbits form the backbone of turbulent pipe flow. Journal of Fluid Mechanics. 833, 274–301.","short":"N.B. Budanur, K. Short, M. Farazmand, A. Willis, P. Cvitanović, Journal of Fluid Mechanics 833 (2017) 274–301.","ieee":"N. B. Budanur, K. Short, M. Farazmand, A. Willis, and P. Cvitanović, “Relative periodic orbits form the backbone of turbulent pipe flow,” <i>Journal of Fluid Mechanics</i>, vol. 833. Cambridge University Press, pp. 274–301, 2017.","apa":"Budanur, N. B., Short, K., Farazmand, M., Willis, A., &#38; Cvitanović, P. (2017). Relative periodic orbits form the backbone of turbulent pipe flow. <i>Journal of Fluid Mechanics</i>. Cambridge University Press. <a href=\"https://doi.org/10.1017/jfm.2017.699\">https://doi.org/10.1017/jfm.2017.699</a>","chicago":"Budanur, Nazmi B, Kimberly Short, Mohammad Farazmand, Ashley Willis, and Predrag Cvitanović. “Relative Periodic Orbits Form the Backbone of Turbulent Pipe Flow.” <i>Journal of Fluid Mechanics</i>. Cambridge University Press, 2017. <a href=\"https://doi.org/10.1017/jfm.2017.699\">https://doi.org/10.1017/jfm.2017.699</a>."},"publication_status":"published","main_file_link":[{"url":"https://arxiv.org/abs/1705.03720","open_access":"1"}],"isi":1,"external_id":{"isi":["000414641700001"]},"title":"Relative periodic orbits form the backbone of turbulent pipe flow","doi":"10.1017/jfm.2017.699","year":"2017"},{"isi":1,"article_number":"R1","main_file_link":[{"open_access":"1","url":"https://arxiv.org/abs/1703.10484"}],"year":"2017","doi":"10.1017/jfm.2017.516","title":"Heteroclinic path to spatially localized chaos in pipe flow","external_id":{"isi":["000408326300001"]},"date_updated":"2023-09-26T16:17:43Z","oa":1,"publist_id":"6824","volume":827,"article_processing_charge":"No","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","quality_controlled":"1","oa_version":"Submitted Version","_id":"824","publication_identifier":{"issn":["00221120"]},"publication_status":"published","citation":{"ama":"Budanur NB, Hof B. Heteroclinic path to spatially localized chaos in pipe flow. <i>Journal of Fluid Mechanics</i>. 2017;827. doi:<a href=\"https://doi.org/10.1017/jfm.2017.516\">10.1017/jfm.2017.516</a>","mla":"Budanur, Nazmi B., and Björn Hof. “Heteroclinic Path to Spatially Localized Chaos in Pipe Flow.” <i>Journal of Fluid Mechanics</i>, vol. 827, R1, Cambridge University Press, 2017, doi:<a href=\"https://doi.org/10.1017/jfm.2017.516\">10.1017/jfm.2017.516</a>.","short":"N.B. Budanur, B. Hof, Journal of Fluid Mechanics 827 (2017).","ista":"Budanur NB, Hof B. 2017. Heteroclinic path to spatially localized chaos in pipe flow. Journal of Fluid Mechanics. 827, R1.","ieee":"N. B. Budanur and B. Hof, “Heteroclinic path to spatially localized chaos in pipe flow,” <i>Journal of Fluid Mechanics</i>, vol. 827. Cambridge University Press, 2017.","apa":"Budanur, N. B., &#38; Hof, B. (2017). Heteroclinic path to spatially localized chaos in pipe flow. <i>Journal of Fluid Mechanics</i>. Cambridge University Press. <a href=\"https://doi.org/10.1017/jfm.2017.516\">https://doi.org/10.1017/jfm.2017.516</a>","chicago":"Budanur, Nazmi B, and Björn Hof. “Heteroclinic Path to Spatially Localized Chaos in Pipe Flow.” <i>Journal of Fluid Mechanics</i>. Cambridge University Press, 2017. <a href=\"https://doi.org/10.1017/jfm.2017.516\">https://doi.org/10.1017/jfm.2017.516</a>."},"author":[{"id":"3EA1010E-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0003-0423-5010","last_name":"Budanur","full_name":"Budanur, Nazmi B","first_name":"Nazmi B"},{"id":"3A374330-F248-11E8-B48F-1D18A9856A87","full_name":"Hof, Björn","last_name":"Hof","orcid":"0000-0003-2057-2754","first_name":"Björn"}],"abstract":[{"text":"In shear flows at transitional Reynolds numbers, localized patches of turbulence, known as puffs, coexist with the laminar flow. Recently, Avila et al. (Phys. Rev. Lett., vol. 110, 2013, 224502) discovered two spatially localized relative periodic solutions for pipe flow, which appeared in a saddle-node bifurcation at low Reynolds number. Combining slicing methods for continuous symmetry reduction with Poincaré sections for the first time in a shear flow setting, we compute and visualize the unstable manifold of the lower-branch solution and show that it extends towards the neighbourhood of the upper-branch solution. Surprisingly, this connection even persists far above the bifurcation point and appears to mediate the first stage of the puff generation: amplification of streamwise localized fluctuations. When the state-space trajectories on the unstable manifold reach the vicinity of the upper branch, corresponding fluctuations expand in space and eventually take the usual shape of a puff.","lang":"eng"}],"department":[{"_id":"BjHo"}],"date_created":"2018-12-11T11:48:42Z","date_published":"2017-08-18T00:00:00Z","month":"08","language":[{"iso":"eng"}],"publisher":"Cambridge University Press","scopus_import":"1","publication":"Journal of Fluid Mechanics","type":"journal_article","day":"18","status":"public","intvolume":"       827"},{"publication_status":"published","citation":{"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>.","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.","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>","short":"D. Xu, S. Warnecke, B. Song, X. Ma, B. Hof, Journal of Fluid Mechanics 831 (2017) 418–432.","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.","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>","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>."},"author":[{"id":"3454D55E-F248-11E8-B48F-1D18A9856A87","first_name":"Duo","full_name":"Xu, Duo","last_name":"Xu"},{"first_name":"Sascha","last_name":"Warnecke","full_name":"Warnecke, Sascha"},{"first_name":"Baofang","last_name":"Song","full_name":"Song, Baofang"},{"id":"34BADBA6-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-0179-9737","full_name":"Ma, Xingyu","last_name":"Ma","first_name":"Xingyu"},{"first_name":"Björn","full_name":"Hof, Björn","last_name":"Hof","orcid":"0000-0003-2057-2754","id":"3A374330-F248-11E8-B48F-1D18A9856A87"}],"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."}],"volume":831,"publist_id":"6922","oa":1,"date_updated":"2023-09-27T12:28:12Z","article_processing_charge":"No","user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","project":[{"call_identifier":"FP7","_id":"25152F3A-B435-11E9-9278-68D0E5697425","name":"Decoding the complexity of turbulence at its origin","grant_number":"306589"}],"quality_controlled":"1","oa_version":"Submitted Version","_id":"745","publication_identifier":{"issn":["00221120"]},"ec_funded":1,"doi":"10.1017/jfm.2017.620","year":"2017","title":"Transition to turbulence in pulsating pipe flow","external_id":{"isi":["000412934800005"]},"isi":1,"main_file_link":[{"url":"https://arxiv.org/abs/1709.03738","open_access":"1"}],"type":"journal_article","day":"25","status":"public","intvolume":"       831","page":"418 - 432","publication":"Journal of Fluid Mechanics","date_published":"2017-11-25T00:00:00Z","month":"11","language":[{"iso":"eng"}],"publisher":"Cambridge University Press","scopus_import":"1","department":[{"_id":"BjHo"}],"date_created":"2018-12-11T11:48:17Z"},{"abstract":[{"text":"Most flows in nature and engineering are turbulent because of their large velocities and spatial scales. Laboratory experiments on rotating quasi-Keplerian flows, for which the angular velocity decreases radially but the angular momentum increases, are however laminar at Reynolds numbers exceeding one million. This is in apparent contradiction to direct numerical simulations showing that in these experiments turbulence transition is triggered by the axial boundaries. We here show numerically that as the Reynolds number increases, turbulence becomes progressively confined to the boundary layers and the flow in the bulk fully relaminarizes. Our findings support that turbulence is unlikely to occur in isothermal constant-density quasi-Keplerian flows.","lang":"eng"}],"author":[{"full_name":"Lopez Alonso, Jose M","last_name":"Lopez Alonso","orcid":"0000-0002-0384-2022","first_name":"Jose M","id":"40770848-F248-11E8-B48F-1D18A9856A87"},{"full_name":"Avila, Marc","last_name":"Avila","first_name":"Marc"}],"publication_status":"published","citation":{"apa":"Lopez Alonso, J. M., &#38; Avila, M. (2017). Boundary layer turbulence in experiments on quasi Keplerian flows. <i>Journal of Fluid Mechanics</i>. Cambridge University Press. <a href=\"https://doi.org/10.1017/jfm.2017.109\">https://doi.org/10.1017/jfm.2017.109</a>","ieee":"J. M. Lopez Alonso and M. Avila, “Boundary layer turbulence in experiments on quasi Keplerian flows,” <i>Journal of Fluid Mechanics</i>, vol. 817. Cambridge University Press, pp. 21–34, 2017.","chicago":"Lopez Alonso, Jose M, and Marc Avila. “Boundary Layer Turbulence in Experiments on Quasi Keplerian Flows.” <i>Journal of Fluid Mechanics</i>. Cambridge University Press, 2017. <a href=\"https://doi.org/10.1017/jfm.2017.109\">https://doi.org/10.1017/jfm.2017.109</a>.","ama":"Lopez Alonso JM, Avila M. Boundary layer turbulence in experiments on quasi Keplerian flows. <i>Journal of Fluid Mechanics</i>. 2017;817:21-34. doi:<a href=\"https://doi.org/10.1017/jfm.2017.109\">10.1017/jfm.2017.109</a>","mla":"Lopez Alonso, Jose M., and Marc Avila. “Boundary Layer Turbulence in Experiments on Quasi Keplerian Flows.” <i>Journal of Fluid Mechanics</i>, vol. 817, Cambridge University Press, 2017, pp. 21–34, doi:<a href=\"https://doi.org/10.1017/jfm.2017.109\">10.1017/jfm.2017.109</a>.","ista":"Lopez Alonso JM, Avila M. 2017. Boundary layer turbulence in experiments on quasi Keplerian flows. Journal of Fluid Mechanics. 817, 21–34.","short":"J.M. Lopez Alonso, M. Avila, Journal of Fluid Mechanics 817 (2017) 21–34."},"_id":"1021","publication_identifier":{"issn":["00221120"]},"user_id":"c635000d-4b10-11ee-a964-aac5a93f6ac1","project":[{"grant_number":"RGP0065/2012","name":"Information processing and computation in fish groups","_id":"255008E4-B435-11E9-9278-68D0E5697425"}],"oa_version":"Submitted Version","quality_controlled":"1","date_updated":"2023-09-22T09:39:46Z","publist_id":"6371","volume":817,"oa":1,"article_processing_charge":"No","external_id":{"isi":["000398179100006"]},"title":"Boundary layer turbulence in experiments on quasi Keplerian flows","year":"2017","doi":"10.1017/jfm.2017.109","isi":1,"main_file_link":[{"url":"https://arxiv.org/abs/1608.05527","open_access":"1"}],"intvolume":"       817","status":"public","day":"25","type":"journal_article","publication":"Journal of Fluid Mechanics","page":"21 - 34","publisher":"Cambridge University Press","scopus_import":"1","language":[{"iso":"eng"}],"month":"04","date_published":"2017-04-25T00:00:00Z","date_created":"2018-12-11T11:49:44Z","department":[{"_id":"BjHo"}]}]