Steady Separation Flow of a Non-Newtonian Fluid through an Axisymmetric Conical Diffuser

Abstract

The laminar steady flow of a non-Newtonian fluid through an axisymmetric conical diffuser is studied numerically. In this calculation, Casson model is used as a constitutive equation of fluid. A finite element method is used for the numerical calculation. The calculation conditions are coincided with the venous flow conditions of man and dog. Results are summarized as follows : 1) The non-Newtonian property of Casson fluid has an effect to decrease the separated flow region, and the decrease in the divergent angle increases the difference of the separated flow region between the Newtonian fluid and Casson fluid. 2) At low Reynolds numbers, the pressure recovery of the Casson fluid is lower than that of the Newtonian fluid, but this ineqality becomes reverse with the increase in the Reynolds number. Thus, it is indicated that the non-Newtonian property of the Casson fluid improves the diffuser's efficiency at high Reynolds numbers.