Laminar External Boundary Layers: Momentum and Heat Transfer

Abstract

Heat transfer from a wedge surface can be obtained by solving the laminar boundary layer energy equation. The boundary layer integral equation may be used to study boundary layer flows with pressure gradient. The authors consider the classical problem of flow over an isothermal semi-infinite flat plate set at zero angle of incidence to a uniform stream of velocity. For low-Prandtl-number fluids, the velocity boundary layer is much thinner than the thermal boundary layer. Since the boundary layer energy equation is linear in temperature, the superposition principle can be used to construct solutions to problems with variable wall temperatures and heat fluxes from simple step function solutions. In some heat transfer problems, the arbitrarily varying heat flux distribution is known, and the surface temperature distribution is required. For the solution of the integral momentum equation, Pohlhausen assumed a fourth-order polynomial for the velocity profile.