Browsing by Author "Niethammer, Barbara"

Now showing 1 - 5 of 5
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    Interfaces, Free Boundaries and Geometric Partial Differential Equations
    (Zürich : EMS Publ. House, 2024) Elliott, Charles M.; Garcke, Harald; Niethammer, Barbara; Simonett, Gieri
    Partial differential equations arising in the context of interfaces and free boundaries encompass a flourishing area of research. The workshop focused on new developments and emerging new themes. At the same time also new interesting results on more traditional areas like, e.g. regularity theory and classical numerical approaches have been addressed. By convening experts from various disciplines related to modeling, analysis, and numerical methods concerning interfaces and free boundaries, the workshop facilitated progress on longstanding open questions and paved the way for novel research directions.
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    Mini-Workshop: Mathematics of Biological Membranes
    (Zürich : EMS Publ. House, 2008) Niethammer, Barbara; Peletier, Mark A.; Röger, Matthias
    [no abstract available]
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    Self-similar rupture of viscous thin films in the strong slip regime
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2009) Peschka, Dirk; Münch, Andreas; Niethammer, Barbara
    We consider rupture of thin viscous films in the strong-slip regime with small Reynolds numbers. Numerical simulations indicate that near the rupture point viscosity and van-der-Waals forces are dominant and that there are self-similar solutions of the second kind. For a corresponding simplified model we rigorously analyse self-similar behaviour. There exists a one-parameter family of self-similar solutions and we establish necessary and sufficient conditions for convergence to any self-similar solution in a certain parameter regime. We also present a conjecture on the domains of attraction of all self-similar solutions which is supported by numerical simulations.
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    Stability of concentrated suspensions under Couette and Poiseuille flow
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2015) Ahnert, Tobias; Münch, Andreas; Niethammer, Barbara; Wagner, Barbara
    The stability of two-dimensional Poiseuille flow and plane Couette flow for concentrated suspensions is investigated. Linear stability analysis of the twophase flow model for both flow geometries shows the existence of a convectively driven instability with increasing growth rates of the unstable modes as the particle volume fraction of the suspension increases. In addition it is shown that there exists a bound for the particle phase viscosity below which the two-phase flow model may become ill-posed as the particle phase approaches its maximum packing fraction. The case of two-dimensional Poiseuille flow gives rise to base state solutions that exhibit a jammed and unyielded region, due to shear-induced migration, as the maximum packing fraction is approached. The stability characteristics of the resulting Bingham-type flow is investigated and connections to the stability problem for the related classical Bingham-flow problem are discussed.
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    Thin film rupture for large slip
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2009) Peschka, Dirk; Münch, Andreas; Niethammer, Barbara
    This paper studies the rupture of thin liquid films on hydrophobic substrates, assuming large slip at the liquidsolid interface. Using a recently developed em strong slip lubrication model, it is shown that the rupture passes through up to three self-similar regimes with different dominant balances and different scaling exponents. For one of these regimes the similarity is of second kind, and the similarity exponent is determined by solving a boundary value problem for a nonlinear ODE. For this regime we also prove finite-time rupture.