Influence of the particle shape on the impact force of lahar on an obstacle

Abstract

I am interested in the evaluation of debris flow impact on structures. I developed a discrete numerical model able to simulate such impacts at the scale of the close surrounding of the structure. The largest particles carried by the flow are modelled explicitly using Distinct Element Method and the finer solid particles are integrated in a fluid phase, which induces two interactions on the largest particles, i.e. buoyancy and drag. The fields of fluid velocity and of fluid free surface are obtained from Computational Fluid Dynamics code then imported in the DEM simulation in a one way coupling scheme. For the results, the influence of particle shape on the impact forces generated on the obstacle is investigated: spherical particles and polygonal rigid blocks (r-blocks) are considered. The shape of the particle influences the contact surface and therefore the impact pressure. With an angular shape and several facets like r-blocks, the impact pressure on an obstacle is more important for a flow with the same characteristics.