Thermophoresis of axially and fore-and-aft symmetric aerosol particles
Journal
Physics of Fluids
Journal Volume
22
Journal Issue
11
Date Issued
2010
Author(s)
Abstract
The thermophoretic motion of an aerosol particle of revolution with fore-and-aft symmetry in a uniformly prescribed temperature gradient normal to its axis of revolution is studied theoretically. The Knudsen number is assumed to be small so that the fluid flow is described by a continuum model. A method of distribution of a set of spherical singularities along the axis of revolution within a prolate particle or on the fundamental plane within an oblate particle is used to find the general solutions for the temperature and fluid velocity fields. The temperature jump and fluid slip conditions at the particle surface are satisfied by applying a boundary collocation technique to these general solutions to determine the unknown coefficients. The thermophoretic velocity of the particle is calculated with good convergence behavior for various cases, and the agreement between our results and the available analytical solutions is very good. It is found that the normalized thermophoretic velocity of a prolate or oblate spheroid perpendicular to its axis of revolution decreases monotonically with an increase in its axial-to-radial aspect ratio. For most practical cases of a spheroid with a specified aspect ratio, its thermophoretic mobility is not a monotonic function of its relative thermal conductivity. For the general problem of a particle with axial and fore-and-aft symmetry undergoing thermophoresis in a temperature gradient oriented arbitrarily with respect to its axis of revolution, the solution of the particle velocity can be obtained as a superposition of the solution obtained previously for the axisymmetric motion of the particle and the current result. © 2010 American Institute of Physics.
Type
journal article