Multi-dimensional rheology-based two-phase model for sediment transport and applications to sheet flow and pipeline scour
- Centre for Offshore Research and Engineering, Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576 (Singapore)
- School of Civil and Environmental Engineering, Nanyang Technological University (Singapore)
Sediment transport is fundamentally a two-phase phenomenon involving fluid and sediments; however, many existing numerical models are one-phase approaches, which are unable to capture the complex fluid-particle and inter-particle interactions. In the last decade, two-phase models have gained traction; however, there are still many limitations in these models. For example, several existing two-phase models are confined to one-dimensional problems; in addition, the existing two-dimensional models simulate only the region outside the sand bed. This paper develops a new three-dimensional two-phase model for simulating sediment transport in the sheet flow condition, incorporating recently published rheological characteristics of sediments. The enduring-contact, inertial, and fluid viscosity effects are considered in determining sediment pressure and stresses, enabling the model to be applicable to a wide range of particle Reynolds number. A k − ε turbulence model is adopted to compute the Reynolds stresses. In addition, a novel numerical scheme is proposed, thus avoiding numerical instability caused by high sediment concentration and allowing the sediment dynamics to be computed both within and outside the sand bed. The present model is applied to two classical problems, namely, sheet flow and scour under a pipeline with favorable results. For sheet flow, the computed velocity is consistent with measured data reported in the literature. For pipeline scour, the computed scour rate beneath the pipeline agrees with previous experimental observations. However, the present model is unable to capture vortex shedding; consequently, the sediment deposition behind the pipeline is overestimated. Sensitivity analyses reveal that model parameters associated with turbulence have strong influence on the computed results.
- OSTI ID:
- 22598955
- Journal Information:
- Physics of Fluids, Vol. 28, Issue 5; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-6631
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
42 ENGINEERING
CONCENTRATION RATIO
FLOW RATE
FLUIDS
ONE-DIMENSIONAL CALCULATIONS
PARTICLE INTERACTIONS
PARTICLES
PIPELINES
REYNOLDS NUMBER
SEDIMENTS
SENSITIVITY ANALYSIS
SHEETS
THREE-DIMENSIONAL CALCULATIONS
TURBULENCE
TWO-DIMENSIONAL CALCULATIONS
TWO-PHASE FLOW
VISCOSITY