Characterization of Active Flow Control for a Generic Vehicle Model

Abstract

This study performed a high-fidelity wall-resolved large-eddy simulations to investigate the impact of active flow control using an unsteady suction on an Ahmed body model with a \(25^\circ \) slant angle. A key goal of this work is the validation of the baseline flow, which yields a drag coefficient in close agreement with the ERCOFTAC benchmark experimental results. A comprehensive analysis is conducted to characterize the influence of the suction on flow topology and turbulence dynamics across the separation, reverse-flow, reattachment, and wake-recovery regions. Flow modifications are examined using qualitative visualizations of mean velocity and pressure coefficient, together with quantitative analyses of first- and higher-order turbulence statistics, including resolved Reynolds stresses. The results reveal that suction control re-energizes the boundary layer near the slant leading edge, modifies the so-called large-scale C-pillar vortices and substantially reduces the recirculation zone. Furthermore, deeper insight is obtained through single probability density functions of resolved velocity fluctuation at multiple downstream locations. In controlled case, the analysis reveals a marked reduction in flow intermittency over the slant surface and in the near-wake.