Experimental investigation of the flow around a simplified ground vehicle under effects of the steady crosswind

Crosswinds which stem from on-road flow conditions can deteriorate a ground vehicle's driving performance. In spite of the numerous studies investigating aerodynamics of the ground vehicles in the previous literature, there is still a need for thorough understanding of the underlying flow phenomena related to crosswind sensitivity of the ground vehicles. Therefore, the present study is aimed to investigate characteristics of the flow features around the ground vehicles under steady crosswind conditions within a range of yaw angles 0° ≤ β ≤ 15° using the Ahmed vehicle model with rear slant angles of α = 25° and 35°. Throughout the investigations, flow visualizations using dye injection technique and velocity measurements using particle image velocimetry PIV technique are conducted. The Reynolds number of the flow which is based on the free stream flow velocity U = 200 mm/s and height of the model H = 72 mm is ReH= 1.4 × 104. Results are presented in terms of time-averaged vorticity <ω> contours and streamline <ψ> patterns together with velocity magnitude ((<u>2+<w>2)1/2/U) of the flow fields. Additionally, turbulence quantities such as Reynolds stresses <u'w'>/U2 and turbulent kinetic energy TKE are presented and discussed in details. Results of the present study show that characteristics of the flow features in the near wake region downstream of the Ahmed model are very sensitive to the effects of the crosswind.