Direct numerical simulation of turbulent heat transfer in plane impinging jet

The objectives of this study are to investigate the structures and characteristics of flows and heat transfer for plane turbulent impinging jets in a confined space, where a wall-jet type of flow is influenced by both lower (impingement) and upper walls, and to obtain turbulent statistics for the construction of a turbulent heat transfer model. For these purposes, we have performed direct numerical simulations (DNS) of impinging flows with heat transfer. To obtain the effects of an impingement distance on heat transfer, the value of H is changed in calculations, where H is the distance between the impingement wall and the upper wall. It is found from the present DNS that the Nusselt number increases with a decrease in the distance H similar to the experimental results. In addition, the Nusselt number of the case with the highest distance decreases monotonously in the wall-jet development direction, while in shorter distance cases the second peak of the Nusselt number is clearly observed away from the stagnation point, due to the increase in wall-normal turbulence intensities in the region away from the stagnation point.