Windbreak and viaduct effects on vehicle aerodynamics: A CFD study
This study presents a numerical analysis of the airflow around a passenger vehicle (DrivAer model in the Notchback configuration) travelling across a viaduct, with the aim of investigating the influence of bridge protection elements on the vehicle's aerodynamic characteristics. CFD simulations were conducted in STAR-CCM+ using the RANS approach coupled with the k-ω SST turbulence model. Four geometric configurations were analysed: open flow without any protection, viaduct with a guardrail, viaduct with a solid windbreak, and viaduct with a porous windbreak. Each configuration was simulated under two flow scenarios, with and without a crosswind component. The CFD model was validated against experimental data obtained from the Technical University of Munich (TUM) wind tunnel, showing satisfactory agreement in the drag and pressure coefficients. The results indicate that the solid windbreaks increase side forces and rolling moments, whereas the porous windbreaks significantly reduce turbulent effects and improves aerodynamic stability. The analysis of the Q - criterion field and turbulent kinetic energy confirms that the porous barrier narrows the wake region and diminishes vortex structures behind the vehicle. It was further established that for passenger vehicles, a well-designed guardrail can achieve comparable or even superior effects to complex windbreak in terms of optimizing aerodynamic loads on the vehicle.