Finite difference analysis of two-dimensional flow around an automobile.

Two-dimensional flow around an automobile is calculated by solving the incompressible Navier-Stokes equations numerically. The basic equations are transformed into a general coodinate system and discretized by a third-order upwind scheme without any turbulent modes. Computational results show small vorticies being generated one after another at the leading edges of the hood and roof, which start to increase in size over the rear window and become extremely large behind the vehicle. The pressure distribution on the surface of the body indicates several minus-peaks corresponding to the vorticies at each time step. However, when the surface pressure is averaged over a long period, agreement with the experimental data measured in a two-dimensional wind tunnel is good.