Numerical investigation of the actuated flow on a bluff body

Abstract

Large Eddy Simulations (LES) are conducted to study the Active Flow Control (AFC) of the separation of the boundary layer on a rounded leading edge frontstep. This bluff body imitates the flow around a section of a simplified truck cabin and focuses on the separation arising at the front rounded corner, the so called A-pillar. The LES data show the connection between the actuation and drag reduction. The actuated and unactuated flows are analysed usingmodal decomposition and frequency analysis. Two different actuation frequencies are tested and a strong influence of the control on both drag reduction and separation mechanism was observed. Relevant results, in terms of drag coefficient and recirculation bubble reduction, are achieved when the flow is actuated. LES shows an increased unsteadiness in the flow, introduced by the actuation. An analysis that investigates the connection between actuation and induced unsteadiness is presented.