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To research the mechanism of automobile aerodynamic noise which transmits to the inside of a cabin, flow structure and sound field have been investigated by applying experimental measurements at the wind tunnel and computational fluid dynamics (CFD) based on lattice Boltzmann method (LBM). In this research, transmitted noise at a front side window glass is focused. Pressure fluctuations on the side window glass contain both hydrodynamic pressure fluctuations induced by convection of flow field and acoustic pressure fluctuations propagated from noise sources. But it was found that acoustic pressure fluctuations have large contributions on the side window glass at the high frequency range by considering of the experimental transmission loss. On the other hand, at the low frequency range, hydrodynamic pressure fluctuations are dominant, however their effects to transmitted noise are not so influential for high fluctuation levels.

Aerodynamic drag reduction is one of the most important aspects of enhancing overall vehicle performance. Many car manufacturers have been working to establish drag reduction techniques. This paper describes the development process of a new small speciality car which achieved coefficient of drag(CD) of 0.25. A description of the test facilities and the systems used for developing the aerodynamic aspect of the car are also introduced briefly.

Computational analysis of a flow field around a complex geometry such as a vehicle configuration becomes more reliable with the use of the most current numerical method. And the flow field around a vehicle with tires and wheel houses is simulated with accuracy. Recent market trends necessitate the use of aerodynamic devices to improve aerodynamic characteristics of a road vehicle. However, due to their complex shape, few computational studies of these devices have been performed. In this paper, a computational analysis system for vehicle aerodynamics is established and it's reliability is discussed. As the effective application of the system, the contribution of movable aerodynamic devices is studied using the system. And the comparison of wind tunnel test results with computational results is desirable.