COMPUTATIONAL METHOD TO IMPROVE CFL CONDITIONS IN FRACTIONAL-STEP METHOD FOR COMPRESSIBLE FLUIDS WITH LOCAL AVERAGING

Abstract

In this paper, we proposed a computational method for thermal interaction problems between compressible fluids and solids, which enables us to improve CFL (Courant-Friedrichs-Lewy) conditions based on the speed of sound. In this method, the updating of density and the local averaging operations for velocities are conducted so that new time-step variables satisfy discretized equations in the implicit pressure calculation stage. Through the application to the natural convection in the cavity containing a thermal conductive solid, it was shown that the present method enables us to calculate low Mach number compressible flows free from CFL conditions based on the speed of sound and decrease the computation time.