Numerical study of turbulent flow over two side-by-side rotating cylinders

In the present study, an investigation has been carried out for the unsteady turbulent flow over two side-by-side rotating circular cylinders of the same diameter. Reynolds-Average Navier-Stokes (RANS) equations along with SST (Shear Stress Transport) model are solved using finite element method in order to study the characteristics of turbulent flow. Linear triangular mesh elements are used for the grid generation of the computational domain. These grids are employed for both velocity and pressure interpolation at different points of the domain. Simulation is performed at a high Reynolds number of Re = 10,000 based on the free stream velocity of the fluid, U∞ and the diameter of the cylinder, D. Besides, the spin ratio (α), which is defined as the ratio of the circumferential velocity (Uθ) and the free stream velocity of the fluid, is varied from 0 to 1. Another governing parameter, gap ratio (T/D) between the two cylinders is also varied from 2 to 4, where T is the transverse distance between the centers of the two cylinders. Influences of two different rotating combinations of the cylinders on the aerodynamic characteristics of the problem are also examined. In one combination, the upper cylinder rotates in the counterclockwise direction, while the lower cylinder rotates in clockwise direction and vice versa. In order to observe the aerodynamic performance of the present model, lift and drag coefficients are computed from the computational results. The wake region behind the rotating cylinders and the separation points over the cylinders are also observed.