MODELING OF TURBULENT BUOYANT FLOW AND HEAT-TRANSFER IN LIQUID-METALS

Turbulent natural convection in a cavity filled with low Prandtl number fluids is investigated. The cavity is either heated from below and cooled from above or heated differentially and the other connecting walls are assumed to be thermally insulated. Direct numerical simulations, and two- and three-dimensional low Reynolds number k-epsilon turbulence models are used. It is shown that the turbulent Prandtl number equal to one or slightly greater than one produces useful results, regardless of the value of molecular Prandtl number. A correlation is suggested for the Nusselt number as a function of Ra Pr (Boussinesq number) for natural convection in a differentially heated cavity. The flow becomes turbulent for Ra Pr > 4.8 x 10(3).