| Motivated by the study of aerosol deposition in a human nasal cavity, a preliminary study was made of deposition in a 90° pipe bend for turbulent flow. Deposition fraction data are presented for different flow Reynolds numbers (10000, 20000 and 30100). The results agree with previous studies, indicating that the effect of the flow Reynolds number on the deposition fraction is not significant; however, a small effect was detected for Stokes number near 0.15. A Reynolds number increase from 10000 to 20000 caused a deposition fraction increase of 0.1. Numerical simulations were done, using the Reynolds Averaged Navier-Stokes (RANS) equations with the Shear Stress Transport turbulence model. Modeling with inertial impaction only, the results agree well with the experimental data; however, they fail to detect the small effect seen experimentally. The inclusion of turbulent particle tracking in the RANS simulation via an eddy interaction model did not improve the results. However, based on an analytical analysis of the particle tracking equation and drawing data from the numerical results, it was hypothesised that the Reynolds number effect on deposition at low Stokes numbers is due to turbulent dispersion. |
