Flow past a circular cylinder with momentum injection: Optimal control cylinder design

The flow past a circular cylinder in the presence of two counter-rotating control cylinders is analytically investigated. It is shown that vortex formation behind a circular cylinder can be suppressed by introducing two small counter-rotating circular cylinders. However, choosing an appropriate position and optimal circulation strength for the control cylinders is central to achieving optimal control cylinder design. Solving the complete Navier-Stokes (NS) equations can be time consuming if we approach parameterizing the position and circulation strength of the control cylinders. Instead, reduced-order models can be employed to save the computational expenditure associated with solving the complete NS models. To this end, a Föppl model is employed to investigate the influence of position of the control cylinders on the flow separation from the main circular cylinder. Conformal mapping techniques are used to investigate the flow features, from which the optimum value of circulation was found based on pressure distribution and drag forces. Analytical solutions are complemented through finite volume-based viscous flow calculations. © 2013 The Japan Society of Fluid Mechanics and IOP Publishing Ltd.