A model for particle removal from surfaces with large-scale roughness in turbulent flows

The resuspension rate of particles from surfaces is significantly dependent on surface roughness. Existing models only consider the case of surface asperities much smaller than particle diameter, but often particle sizes of interest are comparable or smaller than substrate roughness. In this study, a model for particle removal from large-scale roughness is described. Substrate roughness is described using a 2D sinusoidal profile. The critical shear velocity is determined considering rolling detachment of particles with JKR adhesion model and hydrodynamic moments on particles residing on the rough substrates. Our model results show that the effect of surface roughness on critical shear velocity is strongly dependent on the value of roughness amplitude and wavelength relative to particle size. The model predicts four primary removal regions based on relative particle-surface characteristics: easier-to-remove than smooth substrate, more difficult to remove than smooth substrate, not possible to remove, and similar behavior as smooth surface. The model performance is validated by comparison of predictions with published experimental results for highly rough substrates. Copyright © 2019 American Association for Aerosol Research