Numerical aspects of a block structured compressible flow solver

A block structured compressible flow solver based on a finite volume approach with central spatial differencing is described and its performance in 2D on flow around an airfoil is studied. Variations in the number and dimensions of the blocks do not influence the convergence behavior nor the solution, irrespective of the relative positions of a possible shock and the block-interfaces. Mixed calculations, in which the governing equations, either Euler or Reynolds averaged Navier-Stokes, differ per block, give accurate results provided the Euler blocks are defined outside the boundary layer and or in the far field wake region. Likewise, extensive grid distortions near block interfaces can be allowed for outside the boundary layer. Finally, an unbalanced advancement in time, in which each block is advanced independently over several time steps gives no serious decrease in convergence rate.