Numerical study of reduction of fluid forces acting on a square cylinder using a control plate

Abstract

A numerical study on the effects of control plate on the fluid force reduction on a square cylinder has been carried out using lattice Boltzmann method where a configuration of a square cylinder with upstream control plate is studied. In the present computations we have studied the important flow characteristics for 0.1 ≤ l/w ≤ 1 and 1 ≤ g/D ≤ 10. The effects of the l/w and g/D on force reduction, flow separation and vortex shedding frequency have been studied with Reynolds number focused on 150. Vorticity structures, vortex shedding frequency and fluctuating forces and time-mean are presented and discussed. It was found that considerable change in the wake structure and fluid forces depending on the values of l/w and g/D. The numerical results show that there exists an optimum position where the force coefficients acting on the main square cylinder attains their minimum values. At the optimum position, the mean drag coefficient is reduced by 139.3%. Four different flow regimes were identified in this study at different g/D for selected range of l/w. The negative values of drag coefficient for the main square cylinder are also found for different combinations of l/w and g/D.