Discontinuous Galerkin gradient discretisations for the approximation of second-order differential operators in divergence form

International audienceWe include in the Gradient Discretisation Method (GDM) framework two numerical schemes based on Discontinuous Galerkin approximations: the Symmetric Interior Penalty Galerkin (SIPG) method, and the scheme obtained by averaging the jumps in the SIPG method. We prove that these schemes meet the main mathematical gradient discretisation properties on any kind of polytopal mesh, by adapting discrete functional analysis properties to our precise geometrical hypotheses. Therefore, these schemes inherit the general convergence properties of the GDM, which hold for instance in the cases of the p−Laplace problem and of the anisotropic and heterogeneous diffusion problem. This is illustrated by simple 1D and 2Dnumerical examples