Effect of Crosswinds on the Aerodynamics of Two Passenger Cars Crossing Each Other
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The impact of aerodynamics on vehicle safety during crossing of passenger cars is investigated, in the absence and presence of 30 ° crosswind. Three-dimensional, unsteady computational fluid dynamics (CFD) simulations were used to simulate these maneuvers. The vortical structures surrounding one car in the case without crosswind were analyzed, establishing the connection between force and moment fluctuations pre-interaction and the shedding frequency of these vortices. The forces and moments acting on a passenger car during a crossing maneuver may change by up to 43 %, with the maximum change associated with the windward car in the presence of crosswind. However, the duration of this increase in forces is at most 0.01 s, which will not affect the stability of vehicles under normal conditions. The presence of crosswind increased the rate of fluctuation of forces and moments. Wind tunnel experimental results are in good agreement with the simulations, and the data available in literature. The analysis results do not show the necessity of enacting new safety policies on highways, but future parametric studies are needed to fully investigate the impact of different crosswind speeds and directions, the impact of discrepancy in vehicles sizes, and different vehicle lateral separating distances during crossing and overtaking.
Key wordsCar-car crossing Vehicle aerodynamics Computational fluid dynamics Vortical structures
computational fluid dynamics
delayed detached-eddy simulation
improved delayed detached-eddy simulation
Reynolds-averaged Navier-Stokes equations
- x, y, z
drag (in Cd)
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This work has been funded by the US Department of Transportation’s University Transportation Center program, Grant #DTRT13-G-UTC4O through the Pacific Northwest Regional University Transportation Center (PacTrans). The authors would like to thank PacTrans for their support.
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