A comparative study and a mechanistic picture of resuspension of large particles from rough and smooth surfaces in vortex-like fluid flows

Resuspension of freely moving solid particles by a vortex-like flow from surfaces of different roughness is studied using a three-dimensional particle tracking velocimetry (3D-PTV) method. By utilizing the three-dimensional information on particle positions, velocities and accelerations before, during and after the lift-off events, we demonstrate that the resuspension efficiency of the larger than the roughness spherical particles is significantly higher from the rough surface as compared to the smooth surface. The results indicate that for all Reynolds numbers tested, the resuspension rate, as well as the particle velocities and accelerations, is higher over the rough surface, as compared to the smooth counterpart. A mechanistic picture that explains this peculiar effect is proposed. The results can help us to analyze the resuspension rates in engineering and environmental applications of similar flow cases and to improve the specific type of dynamic resuspension models.