The Two-Flux Model Applied to Radiative Transfer and Forced Convection in the Laminar Boundary Layer on a Flat Plate

Abstract

This study presents the analysis of the thermal boundary layer considering combined convection and radiation in an absorbing, emitting, and scattering medium flowing over a flat plate. At high temperatures the presence of thermal radiation alters the temperature distribution in the boundary layer, which in turn affects the heat transfer at the wall. In many industrial applications, such as in the cooling of turbine and compressors blades, radiative heat transfer plays an important role. The treatment of heat transfer by combined convection and radiation in the boundary layer leads to a set of partial differential and integrodifferential equations, which must be solved simultaneously. The exact solutions are seldom possible and the investigators resort to approximate methods. In the present analysis the two-flux model is used to describe the radiative heat flux in the energy equation. This model reduces the equations that govern the problem to a set of coupled partial differential equations. A finite difference scheme, called “method of columns,” is used to transform the resulting equations into an ordinary differential equation system which simplifies the solution. Results for the temperature profile and heat fluxes showed close agreement with the thin and thick limits. The method proposed proves to be useful to investigate the effect of the different radiation parameters on the thermal boundary layer, and also to be accurate enough for engineering applications.