Computational study of heat transfer enhancement for a dimpled surface in a channel

Heat transfer augmentation techniques have gained great importance in different engineering applications to deal with thermal management issues. In this work, a numerical investigation was carried out to see the effects of spherical dimple arrays on heat transfer characteristics in a channel. These effects were observed for dimples on the bottom wall of the channel for laminar airflows. The effects of a 21×7 staggered array and a 19×4 inline array on the bottom wall were investigated using a 3D steady viscous computational fluid dynamics package with an unstructured grid. The heat transfer characteristics were studied as a function of the Reynolds number based on the hydraulic diameter of the channel. The channel height to dimple print diameter ratio was kept constant at H/D=1.0 while the dimple depth to dimple print diameter ratio was kept constant at δ/D=0.2. The heat transfer was quantified by computing the average heat transfer coefficient and Nusselt number. The pressure drop and flow characteristics were also calculated. The Nusselt number was compared with that of a smooth channel without dimples to assess the level of heat transfer enhancement provided by the dimples.;This investigation was carried out to observe if the use of dimples in a channel can enhance heat transfer characteristics without severe penalties associated with pressure drops for laminar airflows. When compared with a smooth channel, the use of dimples enhanced heat transfer. It was also observed that the staggered array facilitates higher heat transfer augmentation when compared to the inline array.