Hybrid RANS/LES computation of plane impinging jet flow

Abstract

Flow characteristics are presented of simulation results of plane impinging jets at high nozzle-plate distances, with two k-ω based hybrid RANS/LES (Reynolds Averaged Navier–Stokes/Large–Eddy Simulation) models and a k-ω RANS model. The first hybrid RANS/LES model is obtained by substitution of the turbulent length scale by the local grid size in the destruction term of the turbulent kinetic energy equation and in the definition of the eddy-viscosity. The second hybrid model is obtained by a latency factor in the definition of the eddy-viscosity. The RANS model overpredicts the length of the jet core region, caused by too weak turbulent mixing in the shear layers of the jet. This results in erroneous near-wall shear stress along the impingement plate. The hybrid RANS/LES models overcome the deficiency of the RANS model. Further, the hybrid models represent the flow with much more detail. For instance, the Görtler vortices are well reproduced in the stagnation flow region by the hybrid RANS/LES models.