Suppression of fluid force on a square cylinder by flow control

A numerical study on reduction of fluid forces acting on a square cylinder (prism) in a two-dimensional channel using a control plate is presented in this paper. In order to control the flow around the square cylinder, a control plate is placed upstream. Fluid forces acting on the square cylinder, vortex shedding frequency and flow patterns are systematically investigated for different heights and positions of the control plate. The control plate height is varied from 10% to 100% of the square side width. For each height, the perpendicular distance between the control plate and the cylinder is varied from 0.5 to 3.0 times of the square width. The Reynolds number considered is 250, based on the square width, and the maximum incoming flow velocity. The technique used for the numerical analysis is the lattice Boltzmann method. Numerical studies show that not only is the drag on the square cylinder significantly reduced by the control plate, but also the fluctuating lift is suppressed as well. The optimum position of the control plate for minimizing the drag on the square cylinder is found for each control plate height.