Control with flaps studied, Turbulence modeling (DDES) validated, Closed-loop control developed.
Results obtained
Following wind tunnel tests on a generic model (Ahmed's body) of a road vehicle and high-performance numerical simulations, promising results were obtained. On the basic model, detailed wake analysis enabled in-depth characterization of the transfer mechanisms between the outer flow and the recirculation bubble behind the body responsible for much of the drag. Comparison of this basic configuration with calculations and experiments has led to the selection of a turbulence model in excellent agreement with experience. This is the DDES. A study of wake flow control was also carried out.
Horizontal and vertical shutters were used. A parametric study was carried out on shutter length and inclination. The impact of horizontal shutters was determined, as was that of vertical shutters. Two cases were selected for further analysis using numerical simulation. We were able to identify the smallest flaps whose effectiveness remains important for application to the real vehicle. We also began experimental and numerical studies on a scale model of a real vehicle (C4). In parallel with these studies, the development of closed-loop control theory has been undertaken. After testing several machine learning methods, reinforcement learning was chosen. A generic, well-documented case (pin ball) with a low Reynolds number. Application of the control yielded encouraging results. 65% drag reduction was achieved.
