Thermophoresis and photophoresis of an aerosol cylinder with thermal stress slip
Journal
American Journal of Heat and Mass Transfer
Journal Volume
4
Journal Issue
2
Pages
85-103
Date Issued
2017
Author(s)
Chang Y.C
Abstract
The thermophoresis and photophoresis of a circular aerosol cylinder normal to its axis in the slip-flow regime (at moderately small Knudsen number) are analyzed with thermal creep, temperature jump, frictional slip, and thermal stress slip at the particle surface. The conservation equations of heat and momentum governing the system at negligible Peclet and Reynolds numbers are solved analytically for the temperature distribution inside and outside the particle and the flow field in the surrounding fluid, and explicit formulas for the thermophoretic and photophoretic velocities of the particle are obtained. The effects of the relative size and optical properties of the particle on its photophoresis are examined from evaluating the heat source function within the particle. It is found that the particle velocities decrease with an increase in the thermal conductivity of the particle relative to the gaseous medium and the effect of thermal stress slip is significant for the case of not too small Knudsen number. The effect of thermal stress slip can augment or reduce the thermophoretic mobility of the particle, depending upon the characteristics of the particle and ambient fluid, but always increases its photophoretic mobility. For specified characteristics of the system, the thermophoretic mobility of an aerosol cylinder is smaller than that of a sphere because of its smaller specific surface area, whereas the photophoretic mobility of a cylindrical particle can be greater or smaller than that of a spherical one. ? 2017 Columbia International Publishing.
Type
journal article