Influence of Variable Thermophysical Properties on Turbulent Combined Heat Transfer in a Vertical Channel

The present paper investigates turbulent mixed convection - radiation flow between two vertical parallel plates kept at different temperatures with variable thermophysical properties. The Reynolds number, based on channel half-width and friction velocity and the Grashof number, based on channel width and wall temperature difference, were assumed to be 150 and 1.6×106, respectively. numerical simulations were carried out by developing a solver in OpenFOAM software, applying finite volume method. Launder-Sharma low-Reynolds RANS based turbulence model was employed. Thermophysical properties approximation (dynamic viscosity and Thermal conductivity coefficient) were based on Sutherland Law and Power Law. The working fluid was assumed to be gray, absorbing, emitting, and scattering. The radiative transfer equation was solved using the discrete ordinates method (DOM). Results show that the variable thermophysical properties condition results in higher Nusselt number on both hot and cold wall sides. Also, the bulk temperature and friction factor increase on hot wall side and decrease on cold wall side. Moreover, the velocity across the channel width and the centerline velocity increase.