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 deposition velocity of particles onto a flat plate exposed to parallel airflow after considering the combined effects of electrophoresis and thermophoresis. This model can account for convection, Brownian diffusion, gravitational settling, thermophoresis, and electrophoresis, and it provides fast calculation times and accurate predictions. Using the GDSM, the effects of the deposition surface size on the deposition velocity are analyzed. When the gravitational effect is dominant for a face-up surface or the attractive electrophoresis effect is dominant, the deposition velocity is estimated to be independent of the deposition surface size. Deposition under the influence of thermophoresis depends on the deposition surface size due to the formation of a thermal boundary layer. Deposition velocities for a 450-mm-long surface are studied under a temperature difference of 40 K and for electric field strengths ranging from 0 to 1000 V/cm.