Influence of local grid refinement on prediction of impinging jet heat transfer using Scale-Resolving-Simulation methods

Abstract

A fine near-wall resolution plays a crucial role in simulations of unsteady heat transfer from a wall. A generation of fine structured grids for a complex domain is cumbersome and requires an enormous number of grid points and a local grid refinement is a possible technique for a grid point reduction. The present study addresses numerical simulations of impinging jet heat transfer on locally refined computational grids using the Scale-Resolving-Simulation methods (DES, LES and PANS). The study is performed at a Reynolds number Re = 23000 and two nozzle-plate distances H/D = 2 and H/D = 6. DES and the PANS model with fk = 0.25 predicted results closest to experimental data. However, DES significantly over-predicted heat transfer at the location r/D = 1 − 2 in the small nozzle-plate distance case (H/D = 2). The decrease of physical resolution in the PANS model resulted in the over-prediction of heat transfer close to the nozzle axis. In conclusion, the influence of the local refinement in the perpendicular direction was rather low compared to the longitudinal direction. Moreover, the local grid refinement improved results predicted by LES and DES in the small nozzle-plate distance case.

Keywords

• Turbulent flow
• Scale-resolving-simulation
• Heat transfer
• Impinging jet
• Local refinement