Detachment of Triboelectrically Charged Bumpy Particles in Turbulent Flows

This study analytically evaluated the removal of charged irregularly shaped particles from rough surfaces in turbulent airflows. Spherical particles with several bumps (protrusions) were used as models for the compact, irregularly shaped particles. It was assumed that the substrate and particle bumps have fine surface roughness. The cases where the particles were charged by the triboelectric mechanism in the presence of an electric field were considered. In this case, the charges were assumed to reside on the particle bumps due to the collisions with dissimilar surfaces. For particles with fixed charges per unit mass, various electrostatic forces, including Coulomb, image, dielectrophoretic, and polarization forces, were considered. The adhesion of bumps was modeled using the improved Johnson-Kendall-Roberts (JKR) adhesion theory, with each bump having fine roughness in contact with rough substrates. The shear velocity required to remove the charged irregularly shaped particles in turbulent flows was evaluated using the theoretical interactions between adhesion, electrostatic, and hydrodynamic forces. The effects of particle size, charge, irregularity, and surface roughness on their detachment were investigated.