Micromechanical features of jet erosion—a numerical perspective

Abstract

The erosion mechanisms driving the particle detachment of a soil under an impinging jet are here analysed from a micromechanical perspective combining the numerical Discrete Element and Lattice Boltzmann methods (DEM-LBM). Firstly, the local hydrodynamic conditions of both free and impinging jets are examined and briefly discussed, particularly on the relevance of the superficial irregularities of the granular assembly, which can dominate the local distribution of hydrodynamic variables over the impingement area. Profiles of both macromechanic and discrete (micromechanic) variables will be put forward. Then, the onset of erosion is reviewed from a topological point of view (locality of first grain motion) on the basis of a parametric study. Finally, the variation of the critical inflow velocity for the initiation of erosion in dependence on the particle size is also examined and briefly discussed.

Relevance of Free Jet Model for Soil Erosion by Impinging Jets

“…Among the studies that have been carried out using this approach, Kuang and co-workers (2013) presented a 3D CFD-DEM model of a turbulent round air jet impinging on a granular bed, focusing mainly on the crater formation induced by the air jet. Concerning the surface erosion of a cohesive soil, the Lattice Boltzmann Method (LBM) has been coupled with the DEM for a micro-mechanical simulation of the 2D laminar impinging jet in (Cuéllar et al 2015;Cuéllar et al 2017), which constitutes the basis for the present study with an extended model. Such combination of the LBM-DEM methods appears as a promising technique for simulating a wide range of geomechanical problems, including soil erosion (Cuéllar et al 2017;Lominé et al 2013), various porous flows (Han and Cundall 2013), the fluidization of soils (Cui et al 2014;Ngoma et al 2018), and immersed granular avalanches (Mutabaruka et al 2014) for instance.…”