Attractors for Singular-Degenerate Porous Medium Type Equations Arising in Models for Biofilm Growth

Abstract: We investigate the long-time behaviour of solutions of a class of singular-degenerate porous medium type equations in bounded Lipschitz domains with mixed Dirichlet-Neumann boundary conditions. The existence of global attractors is shown under very general assumptions. Assuming, in addition, that solutions are globally H\"older continuous and the reaction terms satisfy a suitable sign condition in the vicinity of the degeneracy, we also prove the existence of an exponential attractor, which, in turn, yields the finite fractal dimension of the global attractor. Moreover, we extend the results for scalar equations to systems where the degenerate equation is coupled to a semilinear reaction-diffusion equation. The study of such systems is motivated by models for biofilm growth.