Heat Transfer Coefficient and Aerodynamic Resistance on a Surface with a Single Dimple

Abstract

Recent attention in the field of enhanced heat transfer has focused on heat transfer coefficients and aerodynamic resistance on surfaces of various physical constructions. Experimental investigations have shown that a favorable relationship exists on a concave surface where the dimples are defined as holes with rounded off edges. On such surfaces, dimples may be established which increase the heat transfer coefficient greater than they increase aerodynamic resistance, leading to an overall increase in the rate of heat transfer for an established set of extraneous conditions. The heat transfer coefficient increases at a rate greater than can be attributed to the increasing surface area. This appears due to auto oscillations generated by the cavity under turbulent flow regime. The regime of these auto oscillations is characterized by large scale, non-periodic transverse current oscillations and asymmetrical vortexes within the cavity. The parameters of this regime are dependent upon the depth and radius of the dimple. This study investigates the relationship of these characteristics to the heat transfer coefficient and the aerodynamic resistance on the surface.