Electrostatic deposition of inertially moving charged aerosol particles onto the earthed disk

Abstract

Deposition of charged aerosol particles onto the earthed disk, placed within the flow of particles is analysed with inertia and electric field of the particles taken into account. Equations of motion for particles and Poisson's equation for the electric field potential are solved numerically for different values of dimensionless parameters determining the aerosol flow. Carrier gas is supposed to remain quiescent. The macroparticle method is used to obtain the one-dimensional steady distributions of particle concentration, velocity and electric field far from the obstacle. Two basic flows, corresponding to large and moderate values of Stokes' number St, are indicated and studied. The results of the calculations are compared with the analytical solution of the problem in the case St → ∞. Numerical solution of the two-dimensional problem for steady motion of disperse phase near the disk shows that deposition of particles onto the obstacle strongly depends on Stokes' number: at St ⪢ 1 there is a particle-free shadow behind the disk, and particle trajectories can intersect. At St ≲ 1 the particle velocity field is single-valued, and deposition onto the back side of the disk is possible. Capture coefficients, which represent the main characteristics of particle deposition, are calculated separately for each side of the disk. Typical distribution diagrams for particle concentration and electric fields are given.