Large-eddy simulation of turbulent flow over the DrivAer fastback vehicle model

Abstract Turbulent flow over the DrivAer fastback vehicle model is investigated using large-eddy simulation with particular emphasis on flow separation, vortical structures and unsteady quantities. A systematic and detailed analysis of the flow field is made considering rotating wheels and moving ground floor. Overall features of vortical structures at the cowl top, behind side mirrors, near front and back wheels, at A-, B- and C-pillars and behind the rear end of the vehicle are revealed by investigating velocity and vorticity fields. The rear end is identified to be the main contributor to the pressure force acting on the vehicle, followed by back and front wheels and side mirrors. The resulting pressure force on the upper part of the vehicle, including A-, B-, and C-pillars but excluding the cowl top and side mirrors, is found to be only slightly higher than the contribution of the gap in the cowl top. Flow separation and resulting vortices do not only have an impact on automotive drag, it is also pointed out how unsteadiness in the flow field affects pressure fluctuations. High levels of surface pressure fluctuations are found near side mirrors and front wheels. Similarities in distributions of pressure fluctuations and turbulent kinetic energy are found.

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