Abstract: There are many kinds of turbulence models for automobile external flow field simulation. It is a very important significance to find a kind of turbulence model with high calculation efficiency and precision from the turbulence models for vehicle external flow field simulation. Three equation turbulent model is used to simulate automobile external flow field, because the effect of turbulence spatial scale and turbulence time scale to turbulence transportation is involved in the calculation of eddy viscidity coefficient and more physical mechanism of turbulence transportation is described in the model, therefore, turbulent model has higher calculation precision than shear stress transport (SST) and turbulent model. So, three-equation model is a comparatively ideal numerical simulation model of vehicle external flow field. The presented simulation example of car external flow field with the eddy viscosity type three equation , SST model and turbulent model, through comparison of calculated drag coefficients of car with experimental date, validate the advantages of turbulent model. In additional, the curve of pressure coefficient of car longitudinal symmetry face calculated by three models and wind tunnel pressure coefficient experimental data is compared. Turbulent kinetic energy distribution, velocity vector, exterior streamline graph at the position of 0.1 m away from the car rear simulated by turbulent model, are also shown.

Key words: Eddy viscosity coefficient, Numerical simulation, Turbulent kinemics energy, Turbulent model, Vehicle external flow field