Turbulent flow and heat transfer characteristics of an impinging jet over a heated wall-mounted cube placed in a cross-flow

The present study aims at a large-eddy simulation of a turbulent flow and heat transfer of an impinging jet over a heated cube placed in a cross-flow. A baseline simulation of turbulent heat transfer over the heated cube without the jet-impingement has also been conducted. Based on previous research as well as the present study of the baseline case, it has been observed that heat transfer at the top and side surfaces of the cube is relatively poor; thus, these surfaces may become the principal targets for the jet-impingement cooling strategy. The Navier-Stokes and energy equations are solved using a finite-volume technique that incorporates a shear enhanced Smagorinsky model to account for the effect of unresolved scales. The cross-flow Reynolds number and Prandtl number are chosen to be 3500 (based on the cube size and the average streamwise velocity) and 0.71, respectively, for both the baseline and jet-impinged configurations. The primary goal of this research is to investigate the variations in turbulent structures caused by jet-impingement and their relationship to heat transfer characteristics on cube surfaces. By conducting an invariant analysis of the Reynolds stress tensor, we discuss the aspect of Reynolds stress anisotropy. Furthermore, the dominant components of Reynolds stresses are determined using the Lumley triangle at the top surface and in the wake region of the cube, which is expected to be mainly influenced by jet-impingement. The preliminary investigation shows that the heat transfer at the top surface of the cube is substantially improved due to the impingement of the jet. In addition, a significant improvement in heat transfer is also found at the side surfaces despite having a marginal loss at the rear surface of the cube.