Numerical investigation on the effects of six control rods arranged in equilateral triangular configurations on the fluid flow and forced convection heat transfer from a circular cylinder

The present work deals with heat transfer characteristics as well as fluid flow patterns in a laminar flow regime for a circular cylinder with six control rods arranged in equilateral triangular geometries. The computations are carried out by a finite volume approach using the overset grid method. The unsteady flow at Re= 200, Pr= 0.7 and 7.0 is examined. Effect of the control rods on the suppression of the fluid forces applied on a main cylinder is investigated by numerical solution of the Navier-Stokes equations. Based on the results obtained, the arrangement employed in this study indicates the significant performance in reducing the oscillatory force coefficients of the primary cylinder. Except for some gap ratios, it is indicated that both drag and lift coefficients are much lower than that for a single cylinder. Moreover, forced convection heat transfer is calculated using local and mean Nusselt numbers at the surface of the cylinders. The instantaneous streamlines, the vortices and isothermal contours are presented in order to analyze the temperature field and flow field around the cylinders.