Effects of geometry on the thermal-fluid dynamics of a transition water flow in a square heated asymmetric cavity channel

Abstract

Cavity channels candidate as a promising passive cooling configuration in thermal management. The superior performance and the limited scientific investigation regarding cavity channels dictate the need for better understanding of the thermal-fluid dynamics. To the best knowledge of the authors, there are few works investigating the effect of the geometry on the thermal-fluid dynamics of cavity channels with no focus on thermal data and quantification of the recirculation effect which can depend on geometrical parameters. In this work, numerical RANS simulations were performed in ANSYS Fluent with the kT-kL-ω turbulence model for a transitional water flow in an asymmetric square cavity channel with different attachment angles in the range of 20°–90°. The optimal heat transfer performance in terms of uniform and high Nusselt numbers is provided by the configuration with an angle in the range of approximately 30°–40°. Recirculation plays an important role in enhancing heat transfer and its strength is associated with the penetration capacity in the boundary layer. Two regions of strong and weak recirculation are identified along the channel; when the recirculation is weak, other mechanisms such as the thinning of the thermal boundary layer play a more important role. By increasing the attachment angle it is shown the local thinning of the thermal boundary layer, an augmentation of the magnitude of the negative turbulent heat flux peak, and a similarity of the conductive sublayer thickness with the recirculation strength.