---
_id: '14587'
abstract:
- lang: eng
  text: "This thesis concerns the application of variational methods to the study
    of evolution problems arising in fluid mechanics and in material sciences. The
    main focus is on weak-strong stability properties of some curvature driven interface
    evolution problems, such as the two-phase Navier–Stokes flow with surface tension
    and multiphase mean curvature flow, and on the phase-field approximation of the
    latter. Furthermore, we discuss a variational approach to the study of a class
    of doubly nonlinear wave equations.\r\nFirst, we consider the two-phase Navier–Stokes
    flow with surface tension within a bounded domain. The two fluids are immiscible
    and separated by a sharp interface, which intersects the boundary of the domain
    at a constant contact angle of ninety degree. We devise a suitable concept of
    varifolds solutions for the associated interface evolution problem and we establish
    a weak-strong uniqueness principle in case of a two dimensional ambient space.
    In order to focus on the boundary effects and on the singular geometry of the
    evolving domains, we work for simplicity in the regime of same viscosities for
    the two fluids.\r\nThe core of the thesis consists in the rigorous proof of the
    convergence of the vectorial Allen-Cahn equation towards multiphase mean curvature
    flow for a suitable class of multi- well potentials and for well-prepared initial
    data. We even establish a rate of convergence. Our relative energy approach relies
    on the concept of gradient-flow calibration for branching singularities in multiphase
    mean curvature flow and thus enables us to overcome the limitations of other approaches.
    To the best of the author’s knowledge, our result is the first quantitative and
    unconditional one available in the literature for the vectorial/multiphase setting.\r\nThis
    thesis also contains a first study of weak-strong stability for planar multiphase
    mean curvature flow beyond the singularity resulting from a topology change. Previous
    weak-strong results are indeed limited to time horizons before the first topology
    change of the strong solution. We consider circular topology changes and we prove
    weak-strong stability for BV solutions to planar multiphase mean curvature flow
    beyond the associated singular times by dynamically adapting the strong solutions
    to the weak one by means of a space-time shift.\r\nIn the context of interface
    evolution problems, our proofs for the main results of this thesis are based on
    the relative energy technique, relying on novel suitable notions of relative energy
    functionals, which in particular measure the interface error. Our statements follow
    from the resulting stability estimates for the relative energy associated to the
    problem.\r\nAt last, we introduce a variational approach to the study of nonlinear
    evolution problems. This approach hinges on the minimization of a parameter dependent
    family of convex functionals over entire trajectories, known as Weighted Inertia-Dissipation-Energy
    (WIDE) functionals. We consider a class of doubly nonlinear wave equations and
    establish the convergence, up to subsequences, of the associated WIDE minimizers
    to a solution of the target problem as the parameter goes to zero."
acknowledgement: The research projects contained in this thesis have received funding
  from the European Research Council (ERC) under the European Union’s Horizon 2020
  research and innovation programme (grant agreement No 948819).
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Alice
  full_name: Marveggio, Alice
  id: 25647992-AA84-11E9-9D75-8427E6697425
  last_name: Marveggio
citation:
  ama: Marveggio A. Weak-strong stability and phase-field approximation of interface
    evolution problems in fluid mechanics and in material sciences. 2023. doi:<a href="https://doi.org/10.15479/at:ista:14587">10.15479/at:ista:14587</a>
  apa: Marveggio, A. (2023). <i>Weak-strong stability and phase-field approximation
    of interface evolution problems in fluid mechanics and in material sciences</i>.
    Institute of Science and Technology Austria. <a href="https://doi.org/10.15479/at:ista:14587">https://doi.org/10.15479/at:ista:14587</a>
  chicago: Marveggio, Alice. “Weak-Strong Stability and Phase-Field Approximation
    of Interface Evolution Problems in Fluid Mechanics and in Material Sciences.”
    Institute of Science and Technology Austria, 2023. <a href="https://doi.org/10.15479/at:ista:14587">https://doi.org/10.15479/at:ista:14587</a>.
  ieee: A. Marveggio, “Weak-strong stability and phase-field approximation of interface
    evolution problems in fluid mechanics and in material sciences,” Institute of
    Science and Technology Austria, 2023.
  ista: Marveggio A. 2023. Weak-strong stability and phase-field approximation of
    interface evolution problems in fluid mechanics and in material sciences. Institute
    of Science and Technology Austria.
  mla: Marveggio, Alice. <i>Weak-Strong Stability and Phase-Field Approximation of
    Interface Evolution Problems in Fluid Mechanics and in Material Sciences</i>.
    Institute of Science and Technology Austria, 2023, doi:<a href="https://doi.org/10.15479/at:ista:14587">10.15479/at:ista:14587</a>.
  short: A. Marveggio, Weak-Strong Stability and Phase-Field Approximation of Interface
    Evolution Problems in Fluid Mechanics and in Material Sciences, Institute of Science
    and Technology Austria, 2023.
date_created: 2023-11-21T11:41:05Z
date_published: 2023-11-21T00:00:00Z
date_updated: 2023-11-30T13:25:03Z
day: '21'
ddc:
- '515'
degree_awarded: PhD
department:
- _id: GradSch
- _id: JuFi
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ec_funded: 1
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- _id: 0aa76401-070f-11eb-9043-b5bb049fa26d
  call_identifier: H2020
  grant_number: '948819'
  name: Bridging Scales in Random Materials
publication_identifier:
  issn:
  - 2663 - 337X
publication_status: published
publisher: Institute of Science and Technology Austria
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- first_name: Julian L
  full_name: Fischer, Julian L
  id: 2C12A0B0-F248-11E8-B48F-1D18A9856A87
  last_name: Fischer
  orcid: 0000-0002-0479-558X
title: Weak-strong stability and phase-field approximation of interface evolution
  problems in fluid mechanics and in material sciences
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---
_id: '10007'
abstract:
- lang: eng
  text: The present thesis is concerned with the derivation of weak-strong uniqueness
    principles for curvature driven interface evolution problems not satisfying a
    comparison principle. The specific examples being treated are two-phase Navier-Stokes
    flow with surface tension, modeling the evolution of two incompressible, viscous
    and immiscible fluids separated by a sharp interface, and multiphase mean curvature
    flow, which serves as an idealized model for the motion of grain boundaries in
    an annealing polycrystalline material. Our main results - obtained in joint works
    with Julian Fischer, Tim Laux and Theresa M. Simon - state that prior to the formation
    of geometric singularities due to topology changes, the weak solution concept
    of Abels (Interfaces Free Bound. 9, 2007) to two-phase Navier-Stokes flow with
    surface tension and the weak solution concept of Laux and Otto (Calc. Var. Partial
    Differential Equations 55, 2016) to multiphase mean curvature flow (for networks
    in R^2 or double bubbles in R^3) represents the unique solution to these interface
    evolution problems within the class of classical solutions, respectively. To the
    best of the author's knowledge, for interface evolution problems not admitting
    a geometric comparison principle the derivation of a weak-strong uniqueness principle
    represented an open problem, so that the works contained in the present thesis
    constitute the first positive results in this direction. The key ingredient of
    our approach consists of the introduction of a novel concept of relative entropies
    for a class of curvature driven interface evolution problems, for which the associated
    energy contains an interfacial contribution being proportional to the surface
    area of the evolving (network of) interface(s). The interfacial part of the relative
    entropy gives sufficient control on the interface error between a weak and a classical
    solution, and its time evolution can be computed, at least in principle, for any
    energy dissipating weak solution concept. A resulting stability estimate for the
    relative entropy essentially entails the above mentioned weak-strong uniqueness
    principles. The present thesis contains a detailed introduction to our relative
    entropy approach, which in particular highlights potential applications to other
    problems in curvature driven interface evolution not treated in this thesis.
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Sebastian
  full_name: Hensel, Sebastian
  id: 4D23B7DA-F248-11E8-B48F-1D18A9856A87
  last_name: Hensel
  orcid: 0000-0001-7252-8072
citation:
  ama: 'Hensel S. Curvature driven interface evolution: Uniqueness properties of weak
    solution concepts. 2021. doi:<a href="https://doi.org/10.15479/at:ista:10007">10.15479/at:ista:10007</a>'
  apa: 'Hensel, S. (2021). <i>Curvature driven interface evolution: Uniqueness properties
    of weak solution concepts</i>. Institute of Science and Technology Austria. <a
    href="https://doi.org/10.15479/at:ista:10007">https://doi.org/10.15479/at:ista:10007</a>'
  chicago: 'Hensel, Sebastian. “Curvature Driven Interface Evolution: Uniqueness Properties
    of Weak Solution Concepts.” Institute of Science and Technology Austria, 2021.
    <a href="https://doi.org/10.15479/at:ista:10007">https://doi.org/10.15479/at:ista:10007</a>.'
  ieee: 'S. Hensel, “Curvature driven interface evolution: Uniqueness properties of
    weak solution concepts,” Institute of Science and Technology Austria, 2021.'
  ista: 'Hensel S. 2021. Curvature driven interface evolution: Uniqueness properties
    of weak solution concepts. Institute of Science and Technology Austria.'
  mla: 'Hensel, Sebastian. <i>Curvature Driven Interface Evolution: Uniqueness Properties
    of Weak Solution Concepts</i>. Institute of Science and Technology Austria, 2021,
    doi:<a href="https://doi.org/10.15479/at:ista:10007">10.15479/at:ista:10007</a>.'
  short: 'S. Hensel, Curvature Driven Interface Evolution: Uniqueness Properties of
    Weak Solution Concepts, Institute of Science and Technology Austria, 2021.'
date_created: 2021-09-13T11:12:34Z
date_published: 2021-09-14T00:00:00Z
date_updated: 2023-09-07T13:30:45Z
day: '14'
ddc:
- '515'
degree_awarded: PhD
department:
- _id: GradSch
- _id: JuFi
doi: 10.15479/at:ista:10007
ec_funded: 1
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language:
- iso: eng
month: '09'
oa: 1
oa_version: Published Version
page: '300'
project:
- _id: 2564DBCA-B435-11E9-9278-68D0E5697425
  call_identifier: H2020
  grant_number: '665385'
  name: International IST Doctoral Program
- _id: 0aa76401-070f-11eb-9043-b5bb049fa26d
  call_identifier: H2020
  grant_number: '948819'
  name: Bridging Scales in Random Materials
publication_identifier:
  issn:
  - 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
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status: public
supervisor:
- first_name: Julian L
  full_name: Fischer, Julian L
  id: 2C12A0B0-F248-11E8-B48F-1D18A9856A87
  last_name: Fischer
  orcid: 0000-0002-0479-558X
title: 'Curvature driven interface evolution: Uniqueness properties of weak solution
  concepts'
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2021'
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