A framework for realisable data-driven active flow control using model predictive control applied to a simplified truck wake

We present an efficient and realisable active flow control framework with few non-intrusive sensors. The method builds upon data-driven, reduced-order predictive models based on Long-Short-Term Memory (LSTM) networks and efficient gradient-based Model Predictive Control (MPC). The model uses only surface-mounted pressure probes to infer the wake state, and is trained entirely offline on a dataset built with open-loop actuations, thus avoiding the complexities of online learning. Sparsification of the sensors needed for control from an initially large set is achieved using SHapley Additive exPlanations. A parsimonious set of sensors is then deployed in closed-loop control with MPC. The framework is tested in numerical simulations of a 2D truck model at Reynolds number 500, with pulsed-jet actuators placed in the rear of the truck to control the wake. The parsimonious LSTM-MPC achieved a drag reduction of 12.8%.