Mixture Theory for Turbulent Diffusion of Heavy Particles

摘要

A number of studies have recognized the need to include momentum considerations in order to properly represent certain two-phase flows. However, none of these studies identifies both buoyancy effects and the source of the diffusive flux in the manner presented here. This paper examines the classical sedimentation problem in view of the continuum theory of mixtures. The central object is to identify the source of the diffusive flux that balances the gravitational settling flux of negatively buoyant particles in a steady, uniform mean flow. Mixture theory offers a powerful tool for examination of this problem. It provides a rigorous axiomatic framework for the dynamics of two-phase flow, explicitly including exchanges of momentum between the phases. The theory very clearly demarcates the behavior of the fluid phase, the dispersed particulate phase, and the total mixture. (ERA citation 07:061894)