Clean room applications of particle deposition from stagnation flow: electrostatic effects

A theoretical model is presented to describe particle deposition from plane stagnation flow above a flat surface. An example is given which includes convection, diffusion, sedimentation, Coulombic forces, and image forces. The results suggest that, for typical clean room workbench operating conditions, Coulombic forces dominate the deposition of submicrometer particles even when the surface electric potential is relatively weak. In this regime, the deposition rate is insensitive to freestream velocity. Schemes for reducing particulate contamination should focus on reducing or balancing the Coulombic forces.