Boundary effects on the creeping-flow and thermophoretic motions of an aerosol particle in a spherical cavity

Abstract

An analytical study is presented for the quasisteady translation, rotation, and thermophoresis of an aerosol sphere located at the center of a spherical cavity. The Knudsen number is assumed to be small so that the fluid flow is described by a continuum model with a temperature jump, a thermal creep, and a frictional slip at the solid surfaces. The particle and the cavity surroundings may differ in thermal conductivity and in surface properties. In the limit of small Reynolds and Peclet numbers, the appropriate energy and momentum equations are solved for each system and the particle velocities for an applied force, torque, and temperature gradient are derived individually in closed forms. In general, the boundary effects of the cavity wall on the isothermal creeping-flow and thermophoretic motions of an aerosol particle can be quite significant in appropriate situations. In practical aerosol systems, the boundary effect on thermophoresis is much weaker than that on the motion driven by a gravitation field.