5. Re-entrainment of particles attached to a wall

The main forces involved in the re-entrainment of aerosols attached to a wall are drag and lift forces. Because it is horizontal, the drag force is decisive for particle detachment. However, as the particles are set in motion at virtually right angles, the vertical lift force plays an important role in re-entrainment .

Remember that near the surface of a wall subjected to a gas flow, there are two boundary layers: a concentration boundary layer and a momentum boundary layer, or aerodynamic boundary layer, illustrated in figure 14...