3-DIMENSIONAL UNSTRUCTURED ADAPTIVE MULTIGRID SCHEME FOR THE EULER EQUATIONS

This paper presents a solution adaptive multigrid scheme for the three-dimensional Euler equations. The procedure begins with an initial coarse mesh and enriches this mesh by h-refinement in regions of high solution gradient. This adaptive procedure is used to generate the multigrid levels required by the solver. New boundary nodes are added in a way to reflect the underlying surface representation of the geometry. The h-refinement procedure is extremely fast and results in a scheme Where only a small percentage of the overall CPU time is spent in the meshing and refinement part of the algorithm. The multigrid now solver typically reduces the CPU time by an order of magnitude over the same case without multigrid. Initial mesh generation is achieved through the destructuring of a structured mesh or use of the advancing front method. The algorithm is demonstrated on a range of cases.