MODELING THE TURBULENT HEAT AND MOMENTUM-TRANSFER IN FLOWS UNDER DIFFERENT THERMAL CONDITIONS

Two-equation turbulence models for velocity and temperature (scalar) f ields are developed to calculate wall shear flows under various flow c onditions and related turbulent heat transfer under various wall therm al conditions. In the present models, we make the modified dissipation rates of both turbulent energy and temperature variance zero at a wal l, though the wall limiting behavior of velocity and temperature fluct uations is reproduced exactly. Thus, the models assure computational e xpediency and convergence. Also, the present k-epsilon model is constr ucted using a new type of expression for the Reynolds stress <(u(i)u(j ))over bar> proposed by Abe et al. [Trans. JSME B 61 (1995) 1714-1721] , whose essential feature lies in introducing the explicit algebraic s tress model concept into the nonlinear k-epsilon formulation, and the present two-equation heat transfer model is constructed to properly ta ke into account the effects of wall thermal conditions on the eddy dif fusivity for heat. The models are tested with five typical velocity fi elds and four typical thermal fields. Agreement with experiment and di rect simulation data is quite satisfactory.