Suppression of vortex shedding in the wake of a bluff body by active control

The study of the wake behind the bluff body has been the topic of interest for engineers for the last seven decades. A wide range of real-life applications, including aircraft, bridges, automobiles, and ships, makes vortex shedding an important topic for research. Wake control is vital in the defense application to avoid the trace. Active control of the wake prevails over other passive control methods for the drag reduction for a bluff body with a blunt trailing edge. Therefore active control has been used in the current study. Introducing a secondary flow in the trailing edge of the bluff body prevents the growth of wake bubbles. Thus, the periodic formation of vortices from the trailing edge will be limited due to the smaller wake bubble. Reduced oscillations, in turn, reduce the vorticity across the wake of the bluff body. Hybrid RANS/LES has been used for the current simulation. Improved delayed detached eddy simulation (IDDES) turbulence model is used. OpenFOAM has been used for the simulation. A parametric study is conducted with the velocity ratio of freestream velocity and the injection velocity from the base of the bluff body as the parameter. The numerical model accurately captured the flow development, wake bubble growth, and von-Karman vortex street. The vorticity across the wake of the bluff body with a blunt trailing edge is reduced by 40% to 55% when a secondary flow is introduced at the rear face of the body. Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) sheds light on the dominant frequency and the modes responsible for the vortex shedding.