Towards optimal plasma actuators for friction drag reduction

Plasma actuators have been studied for their ability to generate near wall velocities that can be leveraged to reduce skin-friction drag in turbulent flows. A possible approach is to recreate wall oscillations that have shown to disrupt certain turbulence structures, resulting in reduced drag and potential savings in terms of energy consumption. Nonetheless, differences arise between plasma-induced oscillations and wall oscillation. Investigating these is the main driver of this thesis. Furthemrore, active flow control techniques require energy to function, so extra care must be taken to balance the energy saved and the energy used to activate these techniques. The goal of this study is to identify optimal parameters of plasma actuation for drag reduction in a channel flow. The flow fields are simulated with high-fidelity simulations, coupled with a model of the body force generated by the plasma discharges in the fluid. A Bayesian Optimization algorithm is employed to optimize geometrical and electrical actuation parameters with the final aim to gain information about the drag-reducing properties of the plasma-controlled flows. To reduce computational cost, mainly laminar flows were simulated. Finally the estimated optimal configurations are evaluated in turbulent flows.