Numerical Simultation Of The External Flow Around A Car Body

The study of road vehicle aerodynamics began shortly after automobiles appeared in the world. The knowledge of this research is very important for improvement of dynamic characters of automobiles, for fuel economy and for the stability of movements of the vehicles.Now there are two researching ways of the vehicle aerodynamics: testing and numerical analysis. For testing, a partial-scale model of a tested automobile is placed in a wind tunnel to get the airflow pattern around the automobile. This is a traditional method and very expensive. For numerical analysis the flow field around the tested automobile is numerical calculated. In the last decades, along with the very quick advance of computers and numerical techniques computational fluid dynamics (CFD) has come out as a modern alternative for reducing wind tunnel tests. Recently CFD is applied to various stages of automobile aerodynamics. By contrast to wind tunnel tests, CFD is very cheaper and needs less time to get the flow pattern around a tested automobile. CFD is a very effective researching way not only in automobile aerodynamics, in fact, the new knowledge has been developed first for airplanes, rocket and space shuttles. In these research fields CFD is completely successful. For automobile aerodynamics there are many researching works that have to be completed in future, if CFD could be successfully and widely applied in auto manufacture as in the air flight and space flight.In this paper, the basic knowledge of aerodynamics and CFD is introduced first in Chapter 1-3. In Chapter 4 the theory and the usage of a CFD-software "PHOENICS" is briefly described. In Chapter 5 the 3-dimensional airflow around a car is numerically simulated, using PHOENICS and CAD, and the wake flow is studied in detail. The numerical simulations show the complete airflow pattern around the tested car. This external flow is very complicated because of the geometric complexity of the car body shape and the interaction of the car with the ground. Especially a well-developed turbulence in the wake area is showed.