We consider a quasilinear parabolic system which has the structure of Patlak-Keller-Segel model of chemotaxis and contains a class of models with degenerate diffusion. A cell population is described in terms of volume fraction or density. In the latter case, it is assumed that there is a threshold value which the density of cells cannot exceed. Existence and uniqueness of solutions to the corresponding initial-boundary value problem and existence of space inhomogeneous stationary solutions are discussed....

On étudie la classification des solutions du problème elliptique$${\left({\left|u^{\prime }\right|}^{p-2}{u}^{\prime }\right)}^{\prime }\left(t\right)+{\left({\left|u\right|}^{q-1}u\right)}^{\prime }\left(t\right)-f\left(t\right){\left|u\right|}^{m-1}u\left(t\right)=0,t\>0,$$où $q\>1,p\ge m+1\>2$et $f$ une fonction changeant de signe. En utilisant une méthode de tire, On montre qu’en partant avec une dérivée initiale nulle toutes les solutions sont globales. De plus si $p\>m+1$ et $q\>(p-1)(m+1)/p$ l’ensemble des solutions est constitué d’une seule solution à support compact et de deux familles de solutions ; celles qui sont strictement positives et celles qui changent de signes. On montre aussi que ces deux familles tendent vers l’infini quand...

We compare dewetting characteristics of a thin nonwetting solid film in the absence of stress, for two models of a wetting potential: the exponential and the algebraic. The exponential model is a one-parameter (r) model, and the algebraic model is a two-parameter (r, m) model, where r is the ratio of the characteristic wetting length to the height of the unperturbed film, and m is the exponent of h (film height) in a smooth function that interpolates the system's surface energy above and below...

Le but de cet article est l’étude de la compétition Réaction-Diffusion pour un problème de type ${\displaystyle \beta {\left(w\right)}_t-d_{\epsilon }diva(x,Dw)+r_{\epsilon }g\left(x,\beta \left(w\right)\right)=f,}$ où $\mathbf{a}$ est un opérateur de Lerray-Lions, $\beta$ est une fonction continue croissante et la réaction $g$ est une fonction croissante qui dépend de l’espace $x$. On suppose que les coefficients de diffusion $d_{\epsilon }$ et de Réaction $r_{\epsilon }$ dépendent du paramètre $\epsilon$ avec $d_{\epsilon }$ et/ou $r_{\epsilon }$ tends vers $+\infty$ lorsque ${\displaystyle \epsilon \to 0}$. Dans le cas où, le coefficient de réaction est très rapide, nous étudions le comportement asymptotique lorsque ${\displaystyle t\to \infty }$ de la solution...

The paper presents the results of numerical solution of the evolution law for the constrained mean-curvature flow. This law originates in the theory of phase transitions for crystalline materials and describes the evolution of closed embedded curves with constant enclosed area. It is reformulated by means of the direct method into the system of degenerate parabolic partial differential equations for the curve parametrization. This system is solved numerically and several computational studies are...

The paper presents the results of numerical solution of the Allen-Cahn equation with a non-local term. This equation originally mentioned by Rubinstein and Sternberg in 1992 is related to the mean-curvature flow with the constraint of constant volume enclosed by the evolving curve. We study this motion approximately by the mentioned PDE, generalize the problem by including anisotropy and discuss the computational results obtained.

We consider the Cauchy problem for degenerate parabolic equations with variable coefficients. The equation has nonlinear convective term and degenerate diffusion term which depends on the spatial and time variables. In this paper, we prove the continuous dependence for entropy solutions in the space BV to the problem not only initial function but also all coefficients.

We consider the general parabolic equation :$u_t-\Delta b\left(u\right)+divF\left(u\right)=f$ in $Q=]0,T[\times {ℝ}^N,T\>0$ with ${\displaystyle u_0\in L^{\infty }\left({ℝ}^N\right),}$