Construction of a right inverse for the divergence in non-cylindrical time dependent domains

Abstract

We construct a stable right inverse for the divergence operator in non-cylindrical domains in space-time. The domains are assumed to be Hölder regular in space and evolve continuously in time. The inverse operator is of Bogovskij type, meaning that it attains zero boundary values. We provide estimates in Sobolev spaces of positive and negative order with respect to both time and space variables. The regularity estimates on the operator depend on the assumed Hölder regularity of the domain. The results can naturally be connected to the known theory for Lipschitz domains. As an application, we prove refined pressure estimates for weak and very weak solutions to Navier-Stokes equations in time dependent domains.

Regularity results in 2D fluid-structure interaction

“…for all s > 0 and all p ∈ [1, ∞] and Bog Ωη is the Bogovskii operator on the moving domain. The latter has been extensively analysed in [26] and it is shown that it has the expected properties due to our assumption η ∈ W 1,∞ (I × ω). In particular, we have…”