Hybrid octree/advancing-front mesh generation and implicit agglomeration multigrid Euler solver

This paper develops an unstructured grid methodology for the steady Euler flow over complex geometry. The tetrahedral grid is generated by a hybrid Octree/Advancing-Front method that fully utilizes the efficiency of the Octree method and the body-preserving capability of the Advancing-Front method. The Euler flow solver is a cell-centered upwind finite-volume method based on Frink's interpolation and Roe's approximate Riemann solver. An implicit agglomeration multigrid method is developed to accelerate the convergence to the steady state. High quality coarse grids are obtained with the use of dual cells and the hierarchy of the octree system. Generally the multigrid solution converges three to five times faster than the single grid computation.