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Numerical simulation on three dimensional flow and heat transfer in the engine compartment is presented in this report. As the feature of construction in the engine compartment is complicated, mesh generation is difficult. Therefore, to solve this problem we maked and used code ‘Pre.M’, which auto-generates Cartesian mesh model with NASTRAN data. And this calculation solver is used Cartesian coordinate commercial code ‘STREAM’. In this way, we could reduce the time of making calculation model. Computation was executed for high speed, low speed driving and idling(0km/h), in which steady, incompressible and viscous flow have been simulated using the standard k-ε turbulence model. We have compared the calculation values with experiment values, and considered the flow and heat phenomena.

Conventional aerodynamic simulations have been carried out by using Supercomputer and over a hundred thousand grid points. It takes a long CPU time to get a result. So this method has been mainly used as a research and demonstration tool. In this paper a practical aerodynamic simulation for early phases of the automobile design is presented. This new method basically uses the conventional (wall function used) k-ε turbulent model which is regarded as the most promising in engineering and industrial fields. Firstly, the third-order upwind scheme is introduced to the convective term to improve flow field and pressure distribution. Secondly, the modified turbulent energy production method (M.P.Method) which was proposed by B.E. Launder[3] in 1993, is introduced to the k-ε turbulent model to reduce the excessive generation of turbulent kinetic energy.

The one-box type automobile's stability on the highway is often influenced by encountering crosswinds or when passing large automobiles such as trucks and buses. This causes the automobile to behave unexpectedly. Many experiments for improving this situation have been carried out. In this respect, the analysis of transient aerodynamic characteristics is important for automobile safety and stability on the highway. Conventional transient aerodynamic simulations require a supercomputer and about million grid points. Also there were few case studies that dealt with situations such as plunging into crosswind and passing an automobile. In this paper, a transient aerodynamic simulation by using a sliding mesh of discontinuous interface and the Arbitrary Lagrangian-Eulerian (ALE) method is presented.