Heat Transfer Predictions Using a Dual-Dissipation k-e Turbulence Closure

Abstract

Wall heat transfer predictions, under both low- and high-speed separated flow conditions, are considered using a linear κ-e-R model and a cubic κ-e turbulence closure. The three-equation model is observed not to suffer the impediment of traditional κ-e models of severely overpredicting heat transfer in strongly out-of-equilibrium flow regions. This improvement is due to a dual-dissipation approach in which the destruction term in the κ transport equation (based on a pseudoeddy-viscosity variable R) is independent of the length-scale-determining dissipation e near walls. As a result, turbulence generation level is kept within reasonable bounds in nonequilibrium flow regions. Three flow cases involving wall heat transfer are considered: one in the low-speed regime and the others in the hypersonic regime. The advantage of the κ-e-R model is clearly demonstrated in the high-speed flow cases