Efficient p-multigrid discontinuous Galerkin solver for complex viscous flows on stretched grids

Discontinuous Galerkin methods are very well suited for the construction of very high-order approximations of the Euler and Navier–Stokes equations on unstructured and possibly nonconforming grids but are rather demanding in terms of computational resources. In order to improve their computational efficiency, a p-multigrid solution strategy is here considered for the solution of the Navier–Stokes equations. In particular, a line smoother will be used to alleviate the effect of stretched grids on the convergence rate. The effectiveness and efficiency of the proposed approach in the solution of compressible shockless flow problems is demonstrated on the following 3D viscous test cases: a Delta Wing and a 3D streamlined body.