Finite Element Analysis on Turbulent Flow Over Two Side-by-Side Rotating Cylinders

A numerical investigation has been performed for fully-developed turbulent flow over two side-by-side circular cylinders of the same diameter, both of which rotate in the same direction with the same speed. The governing equation consists of Reynolds-Average Navier-Stokes (RANS) equations along with SST (Shear Stress Transport) turbulence model, which are solved using finite element method in order to evaluate the characteristics of the turbulent flow. To maintain the turbulent flow over the cylinders, computation is carried out at a high Reynolds number of Re = 10000. Parametric simulation is performed for various spin ratios (alpha = U-theta/U-infinity, where U-theta is the circumferential velocity of the cylinder and U-infinity is the free stream velocity of the fluid) from 0 to 1, and gap ratios (T/D, where T is the transverse distance between the centers of two cylinders) from 2 to 4. Effects of two different rotating combinations of the cylinders (clockwise or counter-clockwise) on the aerodynamic characteristics of the fluid flow are examined in terms of lift (C-L) and drag (C-D) coefficients. The wake region behind the rotating cylinders and the separation points over the cylinders are also visualized via streamline and contour plots of pressure field around the cylinders. Simulation results reveal that the direction of the rotation of the cylinders strongly affects the streamlines and the vortex shedding when the spacing between the cylinders is small.