Simulation of sand particle transport by coupled CFD-DEM: first investigations

Plenker, D. and Grabe, J. (2016) Simulation of sand particle transport by coupled CFD-DEM: first investigations. In: ICSE 2016 (8th International Conference on Scour and Erosion), 12-15 September 2016, Oxford, UK.

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Abstract

The continuum based Euler-Euler approach represents the main field of application for the simulation of sediment transport processes. Herein, the decisive phases of free water and soil are modelled by interpenetrating continua. Although mixing of the phases is possible, the multi-component character of the soil phase, as a mixture of solid grains and pore water, is neglected. Hence, a coupling between the free water and the pore water remains unnoticed as well. However, this coupling represents an important factor for determining the current state of the soil boundary near the transition zone. Due to water level changes caused by ship induced bow and stern waves, excess pore water pressure can occur in the upper soil layers. As a result, fluidisation effects can be initiated, which reduce the erosion resistance. To consider these fluidisation effects, the soil has to be treated as a mixture of dispersed grain particles and pore water by a Lagrange-Euler approach. The coupling of the Discrete Element Method (DEM) and the Computational Fluid Dynamics (CFD) approach offers this possibility. Thereby, the DEM is used for modelling the dispersed particles of the Lagrangian regime, while the CFD method models the continuum Euler-phase of the water. This paper introduces the coupled CFD-DEM method for simulating sand particle transport at the boundary layer transition zone. The model investigations and first results of simulations regarding the initiation of motion are presented.

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