Erosion dynamics of particle laden thin film flows over a granular block*

The processes of erosion, deposition, and transportation of particles in a viscous shear flow are crucial for understanding landslides, oil spills in coastal areas, coral reef health, and wastewater treatment. This work presents an experimental study of particle-laden flows over granular blocks. We gathered spatial-temporal data under varying physical parameters to measure erosion rates, speeds, and particle concentrations.We describe a technique combining image processing template matching and particle image velocimetry to determine particle concentration. The results provide insights into a bifurcation of erosion rates affected by critial initial particle volume fractions. Finally, we compared our experimental findings with theoretical predictions using a lubrication model for gravity-driven thin-film flow of viscous fluid and suspended particles.