THERMOPHORETIC DEPOSITION OF SMALL PARTICLES IN LAMINAR TUBE FLOW

The deposition of small particles due to a migration velocity dependent upon temperature gradients (thermophoresis) is studied theoretically for laminar tube flow. The prototype boundary value problem is that in which the wall temperature is suddenly decreased at a given axial position. Because of the ultimate relaxation of the temperature gradient, only some fraction of the particles initially present will deposit on the walls. A Levéque solution for short distances is used to establish a scaling for the deposition efficiency. The effects of weak Brownian diffusion are treated rigorously, and limiting efficiencies for long tubes are determined numerically. Some interesting contrasts between this problem and that for aerosol deposition due solely to diffusion are discussed. © 1979.