On the stability and convergence of Discontinuous Galerkin schemes for incompressible flow

Abstract

The property that the velocity $\mathbf{u}$ belongs to $L^{\infty }(0,T;L^2(\Omega {)}^d)$ is an essential requirement in the definition of energy solutions of models for incompressible fluids. It is, therefore, highly desirable that the solutions produced by discretisation methods are uniformly stable in the $L^{\infty }(0,T;L^2(\Omega {)}^d)$-norm. In this work, we establish that this is indeed the case for Discontinuous Galerkin (DG) discretisations (in time and space) of non-Newtonian models with $p$-structure, assuming that $p\ge \frac{3d+2}{d+2}$; the time discretisation is equivalent to the RadauIIA Implicit Runge-Kutta method. We also prove (weak) convergence of the numerical scheme to the weak solution of the system; this type of convergence result for schemes based on quadrature seems to be new. As an auxiliary result, we also derive Gagliardo-Nirenberg-type inequalities on DG spaces, which might be of independent interest.

convergence proof has been added

References in corpus (1)

• An augmented Lagrangian preconditioner for the magnetohydrodynamics equations at high Reynolds and coupling numbers