URANS computations for an oscillatory non-isothermal triple-jet using the k-ω and second moment closure turbulence models

(L) under bar ow (R) under bar eynolds number turbulence (s) under bar tress and heat (f) under bar lux equation (m) under bar odels (LRSFM) have been developed to enhance predictive capabilities. A new method is proposed for providing the wall boundary condition for dissipation rate of turbulent kinetic energy, epsilon, to improve the model capability upon application of coarse meshes for practical use. The proposed method shows good agreement with accepted correlations and experimental data for flows with various Reynolds and Prandtl numbers including transitional regimes. Also, a mesh width about 5 times or larger than that used in existing models is applicable by using the present boundary condition. The present method thus enhanced computational efficiency in applying the complex turbulence model, LRSFM, to predictions of complicated flows. (U) under bar nsteady (R) under bar eynolds (a) under bar veraged (N) under bar avier-(S) under bar tokes (URANS) computations are conducted for an oscillatory non-isothermal quasi-planar triple-jet. Comparisons are made between an experiment and predictions with the LRSFM and the standard k-epsilon model. A water test facility with three vertical jets, the cold in between two hot jets, simulates temperature fluctuations anticipated at the outlet of a liquid metal fast reactor core. The LRSFM shows good agreement with the experiment, with respect to mean profiles and the oscillatory motion of the flow, while the k-epsilon model under-predicts the mixing due to the oscillation, such that a transverse mean temperature difference remains far downstream. Copyright (C) 2003 John Wiley Sons, Ltd.