Computational analysis of turbulent flow over a bluff body with drag reduction devices

Abstract

Reducing aerodynamic drag of heavy trucks is crucially important for the reduction of fuel consumption and hence results in less air pollution. One way to reduce the aerodynamic drag is the deployment of drag reduction devices at the rear of trucks and this paper describes a numerical study of flow over a bluff body with rear drag devices using the Reynolds-Averaged-Navier-Stokes (RANS) approach to investigate the drag reduction mechanisms and also to assess accuracy of the RANS approach for this kind of flow. Four cases, a baseline case without any drag reduction devices and three cases with different drag reduction devices, have been studied and the predicted mean and turbulent quantities agree well with the experimental data. Drag reduction varies hugely from a few percent in one case to more than 40% in another case and detailed analysis of flow fields has been carried out to understand such a difference and to elucidate the drag reduction mechanism, which ultimately can lead to better design of future drag reduction devices.