A LES Study of Wake Dynamics Control using Upstream Plasma Actuation on a Square Cylinder with Rounded Leading Edges

The control of bluff-body wakes for reduced drag and enhanced stability has traditionally relied on the so-called direct-wake control approach. By the use of actuators or passive devices, one can manipulate the aerodynamic loads that act on the rear of the model. An alternative approach for the manipulation of the flow is to move the position of the actuator upstream, hence interacting with an easier-to-manipulate boundary layer. The present study will focus on a bluff-body flow solved via large-eddy simulations (LES) to investigate the effectiveness of an upstream plasma actuator (positioned at the leading edge) with regard to the manipulation of the wake dynamics and its aerodynamic loads. A rectangular cylinder with rounded leading edges, equipped with actuators positioned at the front curvatures is simulated at Re=40000. This geometry is representative of ground-vehicle configurations, such as truck cabs, and the present study highlights the potential of active flow control for such applications. The results show that sinusoidal actuation yields significantly greater performance than steady actuation. Both drag reduction and cross-flow load attenuation improve with increasing actuation frequency, up to a saturation point. A maximum drag reduction of approximately 40% is achieved in the optimal case.