An h-multigrid approach for high-order discountinuous Galerkin methods

Then we present the development of an h-multigrid method where coarse grid levels are constructed by agglomerating neighbouring elements of the fine grid. First, an elegant yet practical set of transfer operators is de- rived for general space settings and for the current one. After that, a quasi-implicit multistage h-multigrid iteration strategy for the discontinu- ous Galerkin discretization of the steady Euler equations is developed and numerically investigated. Results are presented for a subsonic flow over a NACA0012 airfoil at 2o of incidence. These results highlight the main properties of the developed multigrid scheme and its different behaviour with respect to the classic p-multigrid scheme.