FLOW STRUCTURE AROUND A 3D BLUFF-BODY IN-GROUND PROXIMITY - A COMPUTATIONAL STUDY

A computational model is developed to help the automotive design engin eer to optimize the body shape with minimum wind tunnel testing. Unste ady, Reynolds-averaged, Navier-Stokes equations are solved numerically by a finite-volume method and applied to study the flow around GM's v ehicle-like body. The standard k-epsilon model is employed to model th e turbulence in the flow. The finite volume equations are formulated i n a strong conservative form on a three-dimensional, unstructured grid system. The resulting equations are then solved by an implicit, time marching, pressure-correction based algorithm. The steady state soluti on is obtained by taking sufficient time steps until the flow field ce ases to change with time within a prescribed tolerance. For the pressu re-correction equation, preconditioned conjugate gradient method is em ployed to obtain the solution. Most of the essential features of the f low field around a bluff body in ground proximity, such as the formati on of trailing vortices and the reverse flow region resulting from sep aration, were well predicted. In addition, the variation of drag coeff icient with Reynold's number per meter faithfully follows the experime ntally observed pattern.