Investigation of Forced Convective Heat Transfer around Rotating Elliptic Cylinders

In this research, convective heat transfer in a flow over rotating elliptic cylinders with various axis ratios and rotation rates is investigated numerically. The governing equations including continuity, momentum and energy equations are solved by numerical finite element method. The rotating cylinder was assumed at a constant temperature and heat dissipation to the flow was defined. Numerical analysis was performed by means of COMSOL Multiphysics software. Two domains were defined in the geometry, the rotating one with constant velocity and the second one was assumed to be stationary and the domains are paired to each other. The heat transfer rate and streamlines are obtained for all cases. The unsteady flow is studied when the cylinder starts to rotate suddenly. The results indicate an increase in heat transfer by increasing the rotational ratio. In the higher rotational ratios, the vortices in rotational path of the solid wall are removed and immediately transferred to the edge of the cylinder. In terms of the ratio of heat transfer to drag force, rotating cylinder with axis ratio of unity is the best one.