A finite element method for the surface Stokes problem

TL;DR

This paper introduces a Trace finite element method for solving the surface Stokes problem on embedded 2D surfaces, avoiding surface parametrization and providing stability and optimal error bounds.

Contribution

The paper develops and analyzes a novel TraceFEM for surface Stokes equations using bulk P1 elements, with proven stability and error estimates.

Findings

Method achieves $O(h^2)$ geometric consistency error.

Stable and optimally convergent in surface $H^1$ and $L^2$ norms.

Numerical experiments validate theoretical results.

Abstract

We consider a Stokes problem posed on a 2D surface embedded in a 3D domain. The equations describe an equilibrium, area-preserving tangential flow of a viscous surface fluid and serve as a model problem in the dynamics of material interfaces. In this paper, we develop and analyze a Trace finite element method (TraceFEM) for such a surface Stokes problem. TraceFEM relies on finite element spaces defined on a fixed, surface-independent background mesh which consists of shape-regular tetrahedra. Thus, there is no need for surface parametrization or surface fitting with the mesh. The TraceFEM treated here is based on $P_1$ bulk finite elements for both the velocity and the pressure. In order to enforce the velocity vector field to be tangential to the surface we introduce a penalty term. The method is straightforward to implement and has an $O(h^2)$ geometric consistency error, which is of the same order as the approximation error due to the $P_1$--$P_1$ pair for velocity and pressure. We prove stability and optimal order discretization error bounds in the surface $H^1$ and $L^2$ norms. A series of numerical experiments is presented to illustrate certain features of the proposed TraceFEM.