Modelling of sub-micron-sized particle deposition in a laminar wall jet—an investigation of the role of shielding

The deposition of polystyrene latex particles (0.23 μm in radius) onto a glass surface, covered with indium–tin oxide, has been studied using a wall-jet cell. The particle deposition could be followed in a single experiment at several positions, exposed to a wide range of wall shear rates. A deposition model including a shielding function was applied in order to describe the process. Three shielding functions obtained from the literature, which assumed different shielded areas, were compared. The size of the excluded area was shown to be dependent on the wall shear rate: a higher shear rate resulted in a larger area being blocked by deposited particles, thus preventing non-deposited, free-flowing particles from reaching the surface.