Numerical study on heat transfer and fluid flow past a circular cylinder in the vicinity of a plane wall

This article describes a numerical study on heat transfer and fluid flow for unsteady, incompressible, Newtonian fluid past a circular cylinder in the vicinity of a plane wall. Finite difference implicit method, based on vorticity-stream function formulation with uniform inlet flow conditions, is employed for unsteady state computations for Reynolds numbers in the range 20-200, consistent with a two-dimensional assumption and gap ratios (ratio of distance of the cylinder from the wall to the diameter of the cylinder) in the range between 0.1 and 2.5. With these flow parameters, vortex-shedding and its subsequent effect on heat transfer from the cylinder in the vicinity of a plane wall is investigated. The change of unsteady vortex-shedding regime from two rows of vortices of opposite-sign to single row vortices of same-sign as the cylinder approaches the plane wall can also be viewed from the time-evolution of the average Nusselt number. The vortex-shedding is found to be completely suppressed when the cylinder is located below a critical gap-ratio. The present study shows that a critical gap-ratio is to be maintained to achieve effective heat transfer from the cylinder.