Shangyou Zhang

A new family of stable mixed finite elements for the 3D Stokes equations

A natural mixed-element approach for the Stokes equations in the velocity-pressure formulation would approximate the velocity by continuous piecewise-polynomials and would approximate the pressure by discontinuous piecewise-polynomials of one degree lower. However; many such elements are unstable in 2D and 3D. This paper is devoted to proving that the mixed finite elements of this P k -P k-1 type when k > 3 satisfy the stability condition-the Babuska-Brezzi inequality on macro-tetrahedra meshes where each big tetrahedron is subdivided into four subtetrahedra. This type of mesh simplifies the implementation since it has no restrictions on the initial mesh. The new element also suits the multigrid method.

A Weak Galerkin Finite Element Method for the Maxwell Equations

This paper introduces a numerical scheme for the time-harmonic Maxwell equations by using weak Galerkin (WG) finite element methods. The WG finite element method is based on two operators: discrete weak curl and discrete weak gradient, with appropriately defined stabilizations that enforce a weak continuity of the approximating functions. This WG method is highly flexible by allowing the use of discontinuous approximating functions on arbitrary shape of polyhedra and, at the same time, is parameter free. Optimal-order of convergence is established for the WG approximations in various discrete norms which are either

Higher-dimensional nonnested multigrid methods

H^1

A family of symmetric mixed finite elements for linear elasticity on tetrahedral grids

H1-like or

Optimal order multigrid methods for solving exterior boundary value problems

L^2

A New Divergence-Free Interpolation Operator with Applications to the Darcy-Stokes-Brinkman Equations

L2 and