An augmented fully-mixed formulation for the quasistatic Navier--Stokes--Biot model

TL;DR

This paper presents a new augmented fully-mixed finite element formulation for the coupled Navier-Stokes and Biot equations, enabling stable and accurate simulation of fluid-poroelastic interactions with theoretical guarantees and practical applications.

Contribution

It introduces a novel partially augmented mixed formulation with weakly imposed transmission conditions and stability analysis for fluid-poroelastic problems.

Findings

Proved existence and uniqueness of solutions.

Established stability bounds and convergence rates.

Validated the method with numerical experiments on arterial flow and filtration.

Abstract

We introduce and analyze a partially augmented fully-mixed formulation and a mixed finite element method for the coupled problem arising in the interaction between a free fluid and a poroelastic medium. The flows in the free fluid and poroelastic regions are governed by the Navier-Stokes and Biot equations, respectively, and the transmission conditions are given by mass conservation, balance of fluid force, conservation of momentum, and the Beavers-Joseph-Saffman condition. We apply dual-mixed formulations in both domains, where the symmetry of the Navier-Stokes and poroelastic stress tensors is imposed in an ultra-weak and weak sense. In turn, since the transmission conditions are essential in the fully mixed formulation, they are imposed weakly by introducing the traces of the structure velocity and the poroelastic medium pressure on the interface as the associated Lagrange multipliers. Furthermore, since the fluid convective term requires the velocity to live in a smaller space than usual, we augment the variational formulation with suitable Galerkin type terms. Existence and uniqueness of a solution are established for the continuous weak formulation, as well as a semidiscrete continuous-in-time formulation with non-matching grids, together with the corresponding stability bounds and error analysis with rates of convergence. Several numerical experiments are presented to verify the theoretical results and illustrate the performance of the method for applications to arterial flow and flow through a filter.