Thermophoresis of aerosol particles in laminar flow over inclined plates

Abstract

We analyze numerically the thermophoretic deposition of small particles due to the impingement of a laminar slot jet on an inclined plate. The governing boundary layer type equations are solved by an implicit finite difference technique using grid adaptation for the cold, hot and adiabatic plate conditions. The particle concentration at the cold plate is found to be almost independent of the location along the plate, and of the angle of inclination of the plate as long as the plate temperature (less than the free stream temperature) and thermophoretic coefficient are constant. Adjacent to the hot plate is a critical layer the thickness of which depends upon both the location along the plate and the angle of inclination. Whether this layer is free or full of particles depends upon the product of Prandtl number and thermophoretic coefficient being less than or greater than unity. Results for the adiabatic plate are very similar to those for the hot plate except that the particle concentration gradient is zero at the plate. The dissipation of mechanical energy also has a significant effect on the particle concentration.