Migration of Aerosol Spheres under the Combined Action of Thermophoretic and Gravitational Effects

The migration of an aerosol spherical particle subject to the combined action of gravity and a vertical temperature gradient is considered. In the limit of small Reynolds and Peclet numbers, the solution for the stream function of the fluid flow and the migration velocity of particle is obtained by superposition of the individual solutions for sedimentation and ther-mophoresis. The flow structures for the fluid phase, being illustrated via streamlines in meridian section, reveal complex topology whether in the laboratory frame of reference or a reference frame traveling with the particle. The results demonstrate that fresh intuition must be developed regarding this class of problems.