Fluid Flow and Heat Transfer Studies around Impermeable and Porous Cylinders at Low Reynolds Number using Computational Fluid Dynamics

Abstract

Application of flow past bluff bodies like (cylinders, spheres etc) has been spread to other engineering fields (e.g., ship hydrodynamics, pipelines, heat exchangers in nuclear reactors, cooling systems, skyscrapers etc.) and no more a topic of interest only to aerodynamicists. Porous cylinders with sufficient mechanical properties and strength as of solid cylinders will be preferred due to their better fluid flow and heat transfer properties. In this work, an attempt using computational fluid dynamics (CFD) approach was made to compare the fluid flow and heat transfer properties of the porous square cylinder and square solid cylinder for different low Reynolds numbers. An Unsteady Reynolds Averaged Navier-Stokes (URANS) Equations were solved for the two chosen cylinders where turbulence is introduced into the equations through Shear Stress Transport (SST) k-w model. Heat transfer to the flowing fluid from the cylinders is estimated using the Nusselt number. Brinkman model in conjunction with Forchheimer term has been used to develop the flow through the porous media. The study carried out on 3-Dimensional space using commercial software Ansys. Dependence on grid and mesh has been studied by increasing the number of elements by √2 to verify and validate the methodology followed. The study has been done for different low Reynolds numbers, namely, Re = 170, 185, 200 and 250. The results are encouraging the preference of porous square cylinder than solid square cylinder for few applications.