A study on the improvement of convective heat transfer by using dimpled geometries at different depths and angles in heat sinks

Abstract

In this study, the effect of the combination of dimpled geometries with circular and elliptical shapes in rectangular channels on convective heat transfer and friction factor has been examined numerically. Dimple with ellipse cross-sectional areas were chosen at three different angles: 0°, 60° and 90º. Circular and ellipse-shaped dimple were arranged in a triangle shape, and the distance between the dimple parallel to the flow is 21.6 mm. Two different values were taken for the depth to diameter ratio in both circular and elliptical dimples, these are 0.1 and 0.2. Ansys-Fluent, a commercial code based on the Finite Volume Method (FVM), was used in numerical solutions. The fluid used in the rectangular duct is air. The solutions were verified for both the Nusselt number and the friction factor. After the appropriate turbulence model was selected, numerical solutions were made for all cases understanding the effect of the angle placement of ellipse dimples and the ratio of the depth of the dimples. While friction factor (ftotal) enhanced with dimple depth to diameter ratio, performance decreased with this.