Raindrop Impact on Saturated Soil
Soil erosion is an important environmental phenomenon that causes many side effects such as reduction of soil productivity in the fields and transportation of pollutants to non-contaminated areas. Extensive well designed and controlled flume experiments in Ecological Engineering Laboratory at EPFL revealed that in order to understand some important aspects of erosion process such as morphological changes of the soil surface and crust effects, a detailed mechanistic study of erosion in small scale is needed. In this regard, this work is a start point of small scale simulation to get more interpretation of the soil particle rearrangement as the effect of raindrops. In this paper, particle rearrangement in saturated soil as a result of raindrop impact is studied. A raindrop with specified diameter falls into the container of saturated soil and causes agitation of dense particles inside the container. The aim is to visualize this process by testing the effect of raindrop diameter, particle size and particle physical properties. The numerical solution consists of two steps. At first, the raindrop impact on water surface is simulated using Large Eddy Simulation and VOF method so that the pressure change of the under layer is measured. Then, the profile of the pressure wave is applied on the mixture of water and particles in order to simulate the fluid-particle interaction using Particle-in-Cell (MP-PIC) method. This simulation reveals that the vertical rearrangement of particles has an important effect on crust and compaction process of the soil which needs further investigation. By presentation of this work in 9th OpenFOAM workshop, we intend to introduce the ability of the latest version of OpenFOAM (v 2.3) to simulate dense particle interaction and to discuss on the possibility of development of the solver to have a more robust two-way coupling between CFD and particle based methods such as Discrete Element Method (DEM).