Strictly Uniform Exponential Decay of the Mixed-FEM Discretization for the Wave Equation With Boundary Dissipation

Uniform preservation of stability in approximations of wave equations is a long-standing issue. In this letter, a one-dimensional wave equation with a partially reflective boundary is approximated using a first-order mixed finite element method. The multiplier method is used to prove that the approximated systems are exponentially stable with a decay rate independent of the mesh size. Upper bounds on the exponential decay are obtained in terms of the physical parameters.