Reduction of fluid forces and heat transfer on a square cylinder in a laminar flow regime using a control plate

Highlights: ► This study focuses on the reduction of the fluid forces and heat transfer acting on a square cylinder by a passive control. ► Flow is laminar (Re = 50 to Re = 200). ► The optimum position and width for the control plate are a distance of 3W away from the cylinder and a width of 0.5W. ► Using a control plate delays the onset of the vortex shedding. - Abstract: This study focuses on the reduction of the fluid forces acting on a square cylinder in a laminar flow regime by a passive control, i.e. a flat plate placed upstream of the cylinder. The Reynolds numbers based on the width of the square cylinder (W) and the inlet flow velocity are selected from Re = 50 to Re = 200. The width of the control plate (h) is varied from 0.1W to 0.9W and the distance between the control plate and the cylinder (S) is chosen within the range of 1.1–7W. In these ranges of h and S, the different flow patterns and the magnitude of the reduction of the fluid forces in order to identity the optimum conditions are studied. The results of the heat transfer from a cylinder in the presence of a control plate are also provided for S = 1.1–7W, h = 0.5–0.9W, Re = 160, Pr = 0.71. The results show that the optimum position and width for the control plate are a distance of 3W away from the cylinder and a width of 0.5W, respectively, where the almost maximum reduction of the fluid forces and the minimum reduction of the heat transfer are provided. It is also found that the total Nusselt number of the cylinder in the presence of the control plate decreases for different gap spacings, except for S/W = 1.1.