Application of the "K-ε" model to open channel flows in a magnetic field

In magnetohydrodynamic (MHD) flows turbulence reduction occurs due to the Joule dissipation. It results in heat transfer degradation. In open channel flows, heat transfer degradation is also caused by the turbulence redistribution near the free surface. Both effects can be significant in fusion applications with low-conductivity fluids such as molten salts. In the present study, the "K-epsilon" model equations for turbulent flows and the free surface boundary condition are adjusted with taking into account MHD effects. Different orientations of the magnetic field, perpendicular and parallel to the main flow, have been considered. The model coefficients have been tuned by a computer optimization using available experimental data for the friction factor. The effect of free surface heat transfer degradation due to the turbulence redistribution has been implemented through the variation of the turbulent Prandtl number. As an example, the model is used for the analysis of a turbulent MHD flow down an inclined chute with the heat flux applied to the free surface. (C) 2002 Elsevier Science Ltd. All rights reserved.