Relaminarization of a hot air impingement on a flat plate

Abstract

The research mainly focuses on a numerical analysis for heat transfer in the transition flow regimes. The simulation is presented by using ANSYS-FLUENT and Reynolds Averaged Navier Stokes (RANS) technique is employed in order to simulate the complex flow fields. The turbulent jet which impinges on the flat plate with a constant surface heat fluxes is tested. The average Nusselt number predictions are also calculate and compared with existing measurement results. The jet Reynolds number is set to 23,000 which based on jet nozzle diameter, while a jet-toplate spacing of H/D is fixed at 2.0. The turbulence models evaluated in the present study are one equation Spalart Allmaras (SA) model, k-ϵ, shear stress transport (SST) k-ω and SST with transition model. It can be summarized that the SA, k-ϵ, and SST k-ω models fail to calculate the global trend of the instantaneous simulated Nusselt number profiles. Only the simulated results from the SST with transition model provides agree fairly well with experimental results. Moreover, the first highest point of predicted Nusselt number are close to the stagnation point and decrease monotonically in the radial direction within the wall jet region. The second peak of Nusselt number prediction is also observed, and the RANS simulations can capture the relaminarization mechanisms within the boundary layer near walls.