Three dimensional heat transfer from a square cylinder at low Reynolds numbers

Abstract

Three-dimensional unsteady flow and heat transfer from an isothermal square cylinder subjected to crossflow of air is numerically investigated. The governing continuity, momentum and energy equations are solved using implicit fractional step method. The first order spatial derivatives are discretized using a third-order upwind scheme while the second order derivatives from the viscous terms are discretized by central-difference formula. The momentum equations are solved separately using Crank-Nicholson time-stepping method. The Poisson type equations are solved using Jacobi method with Chebyshev acceleration procedure.The heat transfer characteristics of a square cylinder subjected cross flow of air and the three-dimensionality of the flow and its effects are assessed. Three dimensional instantaneous isotemperature surfaces and in the wake region and local Nusselt number variations on the cylinder surfaces along z-axis were provided. The time histories of the Nusselt numbers at the cylinder surfaces are obtained. Also instantaneous and mean deviation of the local Nusselt numbers on the cylinder surfaces both in spanwise direction and x-y plane are provided for Re = 185 and 250 which are representative of typical A-mode and B-mode vortex structures in spanwise direction respectively.