A Study of the Treatment on the Diffusion Term of Reynolds Stress Equation Model

-Application to a Vehicle Underbody Flow with Imitated Underbody Configurations-

Abstract

This paper compares results via Reynolds stress model (RSM) with those via standard k-εmodel (KEM) for the flow field around the ASMO vehicle body. Positive diffusion is maintained for RSM by applying eddy viscosity type isotropic model. RSM shows a better body surface pressure distribution and C_D than KEM. Secondly, effects of three imitated underbody configurations, i.e.,exhaust pipe, rear suspension and tire house, on C_D value of the vehicle are clarified both via RSM and KEM. A rough underbody configuration does not necessarily increase C_D value compared with flat underbody, showing possibility of the detailed optimization approach for a better underbody configuration.