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Viscosity subsolutions and supersolutions for non-uniformly and degenerate elliptic equations

Aris S. Tersenov (2009)

Archivum Mathematicum

In the present paper we study the Dirichlet boundary value problem for quasilinear elliptic equations including non-uniformly and degenerate ones. In particular, we consider mean curvature equation and pseudo p-Laplace equation as well. It is well-known that the proof of the existence of continuous viscosity solutions is based on Ishii’s implementation of Perron’s method. In order to use this method one has to produce suitable subsolution and supersolution. Here we introduce new methods to construct...

Viscous approach for Linear Hyperbolic Systems with Discontinuous Coefficients

Bruno Fornet (2009)

Annales de la faculté des sciences de Toulouse Mathématiques

We introduce small viscosity solutions of hyperbolic systems with discontinuous coefficients accross the fixed noncharacteristic hypersurface { x d = 0 } . Under a geometric stability assumption, our first result is obtained, in the multi-D framework, for piecewise smooth coefficients. For our second result, the considered operator is 𝔻 t + a ( x ) 𝔻 x , with s i g n ( x a ( x ) ) > 0 (expansive case not included in our first result), thus resulting in an infinity of weak solutions. Proving that this problem is uniformly Evans-stable, we show that...

Viscous Shock Capturing in a Time-Explicit Discontinuous Galerkin Method

A. Klöckner, T. Warburton, J. S. Hesthaven (2011)

Mathematical Modelling of Natural Phenomena

We present a novel, cell-local shock detector for use with discontinuous Galerkin (DG) methods. The output of this detector is a reliably scaled, element-wise smoothness estimate which is suited as a control input to a shock capture mechanism. Using an artificial viscosity in the latter role, we obtain a DG scheme for the numerical solution of nonlinear systems of conservation laws. Building on work by Persson and Peraire, we thoroughly justify the...

Volume Filling Effect in Modelling Chemotaxis

D. Wrzosek (2010)

Mathematical Modelling of Natural Phenomena

The oriented movement of biological cells or organisms in response to a chemical gradient is called chemotaxis. The most interesting situation related to self-organization phenomenon takes place when the cells detect and response to a chemical which is secreted by themselves. Since pioneering works of Patlak (1953) and Keller and Segel (1970) many particularized models have been proposed to describe the aggregation phase of this process. Most of...

Volume mean values of subtemperatures

Neil Watson (2000)

Colloquium Mathematicae

Several authors have found the characteristic mean value formula for temperatures over heat spheres. Those who derived a corresponding formula over heat balls have all chosen different mean values. In this paper we discuss an infinity of possible means over heat balls, and show that, in the wider context of subtemperatures, some are more desirable than others.

Von Kármán equations. III. Solvability of the von Kármán equations with conditions for geometry of the boundary of the domain

Július Cibula (1991)

Applications of Mathematics

Solvability of the general boundary value problem for von Kármán system of nonlinear equations is studied. The problem is reduced to an operator equation. It is shown that the corresponding functional of energy is coercive and weakly lower semicontinuous. Then the functional of energy attains absolute minimum which is a variational solution of the problem.

Vortex collisions and energy-dissipation rates in the Ginzburg–Landau heat flow. Part I: Study of the perturbed Ginzburg–Landau equation

Sylvia Serfaty (2007)

Journal of the European Mathematical Society

We study vortices for solutions of the perturbed Ginzburg–Landau equations Δ u + ( u / ε 2 ) ( 1 | u | 2 ) = f ε where f ε is estimated in L 2 . We prove upper bounds for the Ginzburg–Landau energy in terms of f ε L 2 , and obtain lower bounds for f ε L 2 in terms of the vortices when these form “unbalanced clusters” where i d i 2 ( i d i ) 2 . These results will serve in Part II of this paper to provide estimates on the energy-dissipation rates for solutions of the Ginzburg–Landau heat flow, which allow one to study various phenomena occurring in this flow, including...

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