The Effects of Variable Properties on MHD Flow in Finite Ducts

Abstract

Numerical solutions are obtained of the coupled partial differential equations which describe variable property MHD flow in finite rectangular ducts. The fluid properties are allowed to vary to the extent that electrical conductivity and viscosity are assumed to be temperature-dependent. It is shown that it is not possible to account for fluid property variations in terms of “weighted” fluid parameters such as average Hartmann numbers. Analysis leads to the conclusion that it is the nature of the current distributions in the duct which is important in predicting the behavior of nonisothermal MHD duct flow. It is possible that this conclusion may aid in the evaluation and correlation of experimental data. It is also shown that consideration of variable fluid properties results in friction factors and flow rates which differ from constant property solutions by as much as a factor of two and by 50 percent, even for small variations.