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Numerical prediction of the aerodynamics around cars has long been one of the rudimentary needs in automotive engineering. Despite all of the recent developments in Computational Fluid Dynamics (CFD) and its constituent technologies, however, it’s still not an easy task to accurately predict the flows around and the aerodynamic forces and moments acting on ground vehicles. The complex configurations and flow physics involved in ground-vehicle aerodynamics require, among other things, sophisticated geometry modeling and meshing tools, advanced turbulence models and an efficient solution algorithm. This paper discusses various aspects of applying modern Computational Fluid Dynamics (CFD) to the prediction of aerodynamic flows around ground vehicles.

A numerical method of predicting aeroacoustic performance of HVAC ducts is presented here. The method comprises of two steps. First, the steady state flow structure inside a duct is simulated using computational fluid dynamics (CFD). A k-epsilon based turbulence model is used. In the second step broadband noise source models are used to estimate the sound power generation within the duct. In particular, models estimating dipole and quadrupole sound source strengths are studied. A baseline generic duct geometry was studied with 3 additional design variations. The loudness rankings of these three designs were determined numerically. Simultaneously, the sound generated by these three designs was measured on a flow bench with a microphone kept downstream of the duct outlet. The numerically predicted loudness rankings were compared with experimentally determined rankings and the two are found to be in agreement, thus validating the numerical method.