Multi-dimensional Multiphase Modeling of Sediment Transport
Abstract
Sediment transport driven by waves and currents is of great significance to further predict coastal morphodynamics. Eulerian two-phase models have been shown effective to study sheet flow sediment transport, though most of them are limited to Reynolds-averaged one-dimensional-vertical formulation. Hence, bedform, plug flow and turbulence cannot be resolved. Our goal is to develop four-way coupled multiphase models for multi-dimensional sediment transport under the numerical framework of OpenFOAM for Eulerian modeling and CFDEM for Euler-Lagrangian modeling. In the Eulerian modeling, particle-particle interaction is modeled using the kinetic theory for granular flow for binary collision and phenomenological closure for stresses of enduring contact. To improve the capability of the model for a range of grain sizes, a new closure for the fluid-particle velocity fluctuation correlation in the k-ɛ equations is proposed. The model is validated by comparing the numerical results with laboratory experiments under steady flow and oscillatory flow for grain size ranging from 0.13~0.51 mm. To improve the closure of particle stress and studying poly-dispersed sediment transport processes, an Euler-Lagrangian solver called CFDEM, which couples OpenFOAM for the fluid phase and LIGGGHTS for particle phase, is modified for sand transport in oscillatory flow. Preliminary investigation suggests that even under sheet flow condition, small bed irregularities are observed during flow reversal. These small irregularities later encourage the formation of large sediment cloud during peak flow. 2D/3D simulation of the recent U-tube experiments at Naval Research Laboratory will be carried out to study instabilities in sheet flow and the poly-dispersed effects.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFMEP23D0844C
- Keywords:
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- 0442 BIOGEOSCIENCES / Estuarine and nearshore processes;
- 0550 COMPUTATIONAL GEOPHYSICS / Model verification and validation