Aerosol deposition in circular tubes with simultaneous consideration of diffusion and sedimentation

Abstract Aerosol deposition from laminar flow in a horizontal circular tube is studied analytically considering the combined mechanisms of Brownian diffusion and gravitational settling, and the mean concentration and deposition velocity are calculated and analyzed by using the theoretical solution. The results show that when both diffusional and gravitational effects are considered, the deposition velocity varies non-monotonically with respect to transport distance in the tube. This is different from that of deposition by diffusion alone. For the case when the gravitational effect is negligible, aerosol convective transport in tubes is compared with existing results, and the analysis indicates that the results in the literature dealing with this aspect can be determined by simplifying the present solution under specific conditions. The comparisons of mean concentration due to pure diffusion and combined mechanisms between the previous studies and the present results also indicate that the explicit general solution of this study can be used to describe aerosol deposition at any distance in a horizontal circular tube.