On the Sublayer Model for Turbulent Deposition of Aerosol Particles in the Presence of Gravity and Electric Fields

Abstract

The deposition of neutral and charged aerosol particles from turbulent channel flows is considered. The sub-layer model for the turbulent deposition process is extended to cover the effects of gravity and electrostatic forces. The model is based on the detailed analyses of particle trajectories in the turbulence coherent vortical structures near a wall. The Stokes drag, the Saffman lift, and the gravitational and electrostatic forces are included in the equations of particle motion. The Coulomb, the image, the dielectrophoretic, and the dipole-dipole forces acting on a charged particle near a conducting surface are included in the analysis. Limiting trajectories for various conditions are carefully analyzed. Electrostatic precipitation and gravitational sedimentation in turbulent channel flows are studied in details. Deposition velocities for various particle parameters, flow conditions, and electric field strengths are presented and discussed. The effects of the electrostatic force, the particle density ratio, and the direction of gravity are also examined.