Deposition of aerosol particles in laminar flow over a vertical plate with variable temperatures

Abstract

The deposition of aerosol particles in a laminar flow over a vertical plate with a variable wall temperature of T w (x)=T ∞ +Cx b is considered theoretically. A formula is given to calculate the particle deposition rate. In the process of aerosol particle deposition on the vertical plate, the aerosol particles are driven by two forces: thermophoresis and diffusion. Thermophoresis drives the particles from the high-temperature zone to the low-temperature zone. And diffusion drives the particles from the high-concentration zone to the low-concentration zone. The momentum equation, energy equation, and mass conservation equation are solved to get the deposition rate of the aerosol particles. An approximate solution of the flow field is used to solve the energy and convective diffusion equations. The effects of the Prandtl number Pγ and the wall temperature variable exponent b on the temperature field and the wall temperature gradient are discussed in detail. Two special cases with analytical solutions were chosen to verify the numerical method. The concentration fields were calculated for different wall temperature distributions. The thermophoresis deposition was compared with the diffusion deposition. The results are used to discuss factors influencing the particle concentration and the temperature gradient at the plate and to compare thermophoretic and diffusion deposition. The aerosol particle deposition rate to the plate and the particle concentration distribution were calculated for a fixed set of physical properties.