A Taylor–Hood Finite Element Method for the Surface Stokes Problem Without Penalization

Abstract. Finite element approximation of the velocity-pressure formulation of the surface Stokes equations is challenging because it is typically not possible to enforce both tangentiality and [Formula: see text] conformity of the velocity field. Most previous works concerning finite element methods (FEMs) for these equations thus have weakly enforced one of these two constraints by penalization or a Lagrange multiplier formulation. Recently in [ 11 ] the authors constructed a surface Stokes FEM based on the MINI element which is tangentially conforming and [Formula: see text] nonconforming, but possesses sufficient weak continuity properties to circumvent the need for penalization. The key to this method is construction of velocity degrees of freedom lying on element edges and vertices using an auxiliary Piola transform. In this work we extend this methodology to construct Taylor–Hood surface FEMs. The resulting method is shown to achieve optimal-order convergence when the edge degrees of freedom for the velocity space are placed at Gauss–Lobatto nodes. Numerical experiments confirm that this nonstandard placement of nodes is necessary to achieve optimal convergence orders.