Aerodynamic resuspension of irregular flat micro-particles

Abstract

This study investigates the role of particle shape on the aerodynamic resuspension process ofirregular flat micro-particles on a substrate. We propose that these particles resuspend at highervelocities than spherical ones of the same size under the same aerodynamic forces. Two sets ofdata are analyzed to test the argument, the first from experiments we conducted using crushedglass particles (ranging from 80 μm to 300 μm) and the second from published data on RDXexplosive residue particles (sized between 10 μm and 25 μm) published previously.We particularly analyze the shape factors of the particles used in the experiments and introducethem into a Monte Carlo (MC) simulation model. The probabilities for the time evolution of theresuspension process are calculated through a Markov chain of states. The transition probabilitiesentail the balance between the forces and moments involved in the mechanisms for particledetachment from the surface.The particle resuspension rate as a function of the fluid velocity is evaluated both experimentaland numerically. Additionally, we assess the removal efficiency for different particle size rangeswhenever possible.Both experimental and numerical results demonstrate that the resuspension fraction of irregularflat particles is significantly lower than for equally sized glass microspheres under the sameconditions. Simulations corroborate previous experimental findings, indicating that smallerirregular particles exhibit higher removal efficiency. According to the MC model results, irregularparticles detach by sliding rather than rolling.