Control of thermal and fluid flow characteristics of an oscillating cylinder by porous media

Abstract

The present research aims to study the effect of variables including permeability and thickness of porous media on the thermal and hydrodynamic behavior of an oscillating cylinder at a constant temperature. The finite volume technique is employed to model the flow field for various thicknesses of the porous layer and Darcy numbers at low Reynolds numbers. According to the results, raising the Reynolds number and decreasing the Darcy number will reduce the length of the wakes created behind the cylinder. The separation point occurs earlier as the permeability decreases. Additionally, increasing the porous media thickness and decreasing the Darcy number leads to a decline in the amplitude of oscillation of lift and drag coefficient and amplitude of oscillation in lateral and longitudinal directions. Using the porous layer, the amplitude of the displacement of the cylinder is reduced by about 55 %. Thickness, Darcy number, and the thermal conductivity ratio influence the average variation of the Nusselt number in porous media. For any Darcy number with a specific thermal conductivity ratio, the Nusselt number of the cylinder with a porous layer is larger than the one without porous media. For the oscillating cylinder with Da = 0.001, Re = 90, ks/kf = 1000 and a 0.3 porous layer thickness, it has been taken for a 25 % augment in heat transfer.