ACCURATE FLUX VECTOR SPLITTING FOR SHOCKS AND SHEAR LAYERS

The advection upstream splitting method (AUSM) was recently developed by Lieu and Steffen for accurate predictions of viscous flows. The spe cial merits of AUSM compared to other upwind schemes are the low compu tational complexity and the low numerical diffusion. However, it is kn own that the original method also has several deficiencies. It locally produces pressure oscillations in the vicinity of shocks and in cases of adverse grid situations and flow alignment, In this paper a hybrid flux vector splitting scheme is proposed which switches from AUSM to van Leer at shock waves, ensuring a sharp and clean resolution of stro ng shocks. In order to achieve sufficient damping, a modified dissipat ive term is introduced, which prevents the scheme from being undamped as the Mach number approaches zero. Various modifications of the stand ard MUSCL implementations for second-order accuracy are proposed, whic h yield an accurate resolution of viscous shear layers without spuriou s oscillations. The ability of the improved flux vector splitting sche me is demonstrated by the computation of two- and three-dimensional vi scous flows. (C) 1995 Academic Press. Inc.