Variational methods for fluid-structure interaction and porous media

In this work we consider a poroelastic, flexible material that may deform largely, which is situated in an incompressible fluid driven by the Navier-Stokes equations in two or three space dimensions. By a variational approach we show existence of weak solutions for a class of such coupled systems. We consider the unsteady case, this means that the PDE for the poroelastic solid involves the Frechet-derivative of a non-convex functional as well as (second order in time) inertia terms.(c) 2022 Published by Elsevier Ltd.