ACCURACY OF FLUX-SPLIT ALGORITHMS IN HIGH-SPEED VISCOUS FLOWS

The flux-vector split methods of MacCormack and Candler (MC) and of van Leer (vL) and the flux-difference split method of Roe are investigated in problems representative of complex flows under laminar conditions: the blunt-body flow at Mach 16 and the now past a 24-deg compression corner at Mach 14. Higher order accuracy is obtained with the monotonic upwind-centered scheme for conservation laws (MUSCL) approach, viscous terms are centrally differenced, and an implicit relaxation method is employed for time integration. Emphasis is placed on evaluating the accuracy in prediction of surface quantities of engineering interest. The performance of the schemes is problem dependent. For the flow past the blunt body, the surface pressure is insensitive to the method as well as mesh resolution. Both the MC and Roe schemes predict accurate heat transfer rates whereas results with the vL method are dependent on the limiter employed. The overall distinction between the schemes is diminished for the compression corner especially on finer meshes. The extent of the separation region is notably influenced by the choice of the limiter. Several issues relating to the components of the calculation method are examined.