Gaussian diffusion sphere model to predict deposition velocities under the combined effects of electrophoresis and thermophoresis

Abstract

The Gaussian diffusion sphere model (GDSM) is proposed to predict the average depositionvelocity of particles onto a flat plate exposed to parallel airflow after considering the combinedeffects of electrophoresis and thermophoresis. This model can account for convection, Browniandiffusion, gravitational settling, thermophoresis, and electrophoresis, and it provides fast calculationtimes and accurate predictions. Using the GDSM, the effects of the deposition surface size onthe deposition velocity are analyzed. When the gravitational effect is dominant for a face-upsurface or the attractive electrophoresis effect is dominant, the deposition velocity is estimatedto be independent of the deposition surface size. Deposition under the influence of thermophoresisdepends on the deposition surface size due to the formation of a thermal boundary layer. Depositionvelocities for a 450-mm-long surface are studied under a temperature difference of 40 K and forelectric field strengths ranging from 0 to 1000 V/cm.