The effect of stable stratification and thermophoresis on fine particle deposition in a bounded turbulent flow

Small inertial particle transfer and deposition in a thermally stratified turbulent channel flow is studied by large eddy simulation. The Lagrangian tracking approach is used to describe the dynamics of particles. The objective of this study is to examine the influences of thermal stratification and the thermophoresis on the preferential concentration and deposition of small particles with different particle relaxation time scales. The diameters of particle are ranged from 0.6 μm to 5 μm. Numerical results show that the thermophoresis strengthens the deposition of particles near the cold wall while it weakens the deposition near the hot wall. With the Richardson number increases, the particle mean velocity increases regularly in the core of the channel, and the particle fluctuation intensities decrease due to the re-laminarization tendency of stably stratified turbulent boundary layer. The magnitude of the thermophoretic force on particles decreases in the stable stratified flow, which results in smaller deposition rate with increasing the Richardson number.