Coupled DEM and CFD Simulations of Soil Erosion

In this paper, a fluid-solid interaction model has been built by coupling two numerical methods, computational fluid dynamics (CFD) and discrete element method (DEM). By solving locally averaged Navier-Stokes equation for fluid phase and Newton’s Laws of Motion for particle phase, the meso-scale behaviors of fluid-solid systems can be well captured in this model. The coupled model has been verified by two simple experiments: free settling of a single particle and sandpile formation in water. The results show this coupled model explains both particle phase and fluid phase accurately. To get a further understanding of soil erosion in laminar and turbulent flows, a k – ε turbulent model has been implemented into the fluid phase. Comparison between laminar and turbulent models indicates that soil erosion rate can be five times faster in turbulent conditions. Further accurate experimental verifications are still needed considering the complicated interaction forces between fluid and particles and among clay minerals. This framework shows the ability to help to understand soil erosion mechanism for clay and sand in both laminar and turbulent flows.