Wall Migration and Shear-Induced Diffusion of Fluid Droplets in Emulsions

Published

January 1, 2003

Author(s)

Steven D. Hudson

Abstract

The spatial distribution of drops in multiphase flow through narrow passages is analyzed theoretically and experimentally. In simple shear between two plates, drops migrate away from the walls and concentrate towards the center of the gap. At steady state, this flux is balanced by shear-induced diffusion. By integrating the non-linear convective-diffusion equation, an analytical expression is obtained that gives the steady-state drop concentration as a function of a single dimensionless parameter. Larger drop size and capillary number (Ca), and smaller gap spacing and total concentration, favor migration towards the center. Typically, the migration effect is significant even when droplets are 100 times smaller than the gap. The relationship of gradient- and self-diffusivity of drops is discussed. Non-uniform concentration along the vorticity axis is also investigated briefly.

Citation

Physics of Fluids

Volume

15(5)

Pub Type

Journals

Download Paper

Local Download

Keywords

emulisions, flow-induced morphology, shear induced drop-diffusion, shear-induced drop migration, surface properties

Citation

Hudson, S. (2003), Wall Migration and Shear-Induced Diffusion of Fluid Droplets in Emulsions, Physics of Fluids, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852077 (Accessed April 19, 2024)