Existence and regularity for a system of porous medium equations with small cross-diffusion and nonlocal drifts

Luca Alasio; Maria Bruna; Simone Fagioli; Simon Schulz

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arXiv · 2105.14037

Existence and regularity for a system of porous medium equations with small cross-diffusion and nonlocal drifts

Luca Alasio·Maria Bruna·Simone Fagioli·Simon Schulz

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Abstract

We prove existence and Sobolev regularity of solutions of a nonlinear system of degenerate-parabolic PDEs with self- and cross-diffusion, transport/confinement and nonlocal interaction terms. The macroscopic system of PDEs is formally derived from a large particle system and models the evolution of an arbitrary number of species with quadratic porous-medium interactions in a bounded domain $\Omega$ in any spatial dimension. The cross interactions between different species are scaled by a parameter $\delta<1$, with the $\delta= 0$ case corresponding to no interactions across species. A smallness condition on $\delta$ ensures existence of solutions up to an arbitrary time $T>0$ in a subspace of $L^2(0,T;H^1(\Omega))$. This is shown via a Schauder fixed point argument for a regularised system combined with a vanishing diffusivity approach. The behaviour of solutions for extreme values of $\delta$ is studied numerically.

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Luca Alasio, Maria Bruna, Simone Fagioli, Simon Schulz. 2021-05-28. Existence and regularity for a system of porous medium equations with small cross-diffusion and nonlocal drifts. https://arxiv.org/abs/2105.14037

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