The Role of Spanwise Forcing on Vortex Shedding Suppression in a Flow Past a Cylinder
Controlling the wake vortex dynamics of bluff bodies efficiently is a fundamental problem in many applications. Earlier direct numerical simulations (Darekar and Sherwin) of three-dimensional bluff bodies demonstrated that the introduction of a spanwise waviness at both the leading and trailing surfaces suppresses the vortex shedding and reduces the amplitude of the fluctuating aerodynamic forces. Under this motivation, starting from a fully developed shedding, a sufficiently high spanwise forcing is introduced on the surface of the cylinder, in the regions where separation effects occur, resulting in the stabilisation of the near wake in a time-independent state, similar to the effect of a sinusoidal stagnation surface. Stability analysis of the linearised Navier-Stokes equations was then performed on the three-dimensional flows to investigate the role of the spanwise modulation on the absolute instability associated with the von Kármán street.
KeywordsDirect Numerical Simulation Drag Reduction Bluff Body Spanwise Direction Absolute Instability
G.R. wishes to acknowledge support from UK EPSRC grant EP/H050507/1 “Advanced Instability Methods”. S.J.S. would like to acknowledge support from the McLaren Racing/Royal Academy of Engineering Research Chair.
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