TURBULENT FREE CONVECTION FROM A VERTICAL, ISOTHERMAL PLATE

Abstract

The temperature and velocity fields adjacent to an isothermal, vertical plate have been calculated by finite-difference methods using the time-averaged equations of conservation. Effective diffusivities for turbulent transfer were computed from differential balances for the turbulent kinetic energy and the rate of dissipation of turbulent energy, using the empirical coefficients previously evaluated for forced convection together with an additional Prandtl-number-dependent coefficient associated with the buoyant production of turbulent kinetic energy. Although the turbulent boundary layer almost approaches an asymptotic condition, the slight development requires a two-dimensional solution proceeding from the leading edge through the laminar and turbulent regimes. It was necessary to trigger the transition from laminar to turbulent motion, but the ultimate turbulent behavior was found to be independent of the point of triggering. The computed velocity fields, temperature fields, and rates of heat transfer ...