Layered patterns in reaction-diffusion models with Perona-Malik diffusions

Abstract: In this paper we deal with a reaction-diffusion equation in a bounded interval of the real line with a nonlinear diffusion of Perona-Malik's type and a balanced bistable reaction term. Under very general assumptions, we study the persistence of layered solutions, showing that it strongly depends on the behavior of the reaction term close to the stable equilibria $\pm1$, described by a parameter $\theta>1$. If $\theta\in(1,2)$, we prove existence of steady states oscillating (and touching) $\pm1$, called $compactons$, while in the case $\theta=2$ we prove the presence of $metastable$ $solutions$, namely solutions with a transition layer structure which is maintained for an exponentially long time. Finally, for $\theta>2$, solutions with an unstable transition layer structure persist only for an algebraically long time.