Uniform block diagonal preconditioners for divergence-conforming HDG Methods for the generalized Stokes problem and linear elasticity

We propose a uniform block diagonal preconditioner for the condensed $H$(div)-conforming HDG scheme of a parameter-dependent saddle point problem that includes the generalized Stokes problem and linear elasticity. An optimal preconditioner is obtained for the stiffness matrix for the velocity/displacement block via auxiliary space preconditioning (ASP) technique. A robust preconditioner spectrally equivalent to the Schur complement of element-piecewise constant pressure space is also constructed. Finally, numerical results of generalized Stokes and steady linear elasticity equations verify the robustness of our proposed preconditioner with respect to mesh size, Lam\'e parameters and time step size.