Two-phase model for sand transport in sheet flow regime

Onshore/offshore sediment transport in the nearshore is an important mechanism driving the evolution of coastal morphology. The so-called sheet flow is a transport regime, in which the flow forces are intense such that a large amount of transport occurs in a concentrated layer near the bed. Onshore transport is often associated with flow skewness/asymmetry. In the nearshore zone, due to the bottom slope and wave shoaling, the wave velocity tends be onshore skewed before breaking in the surf zone. For breaking waves, the velocity asymmetry (or acceleration skewness) may also play a key role in determining net sediment transport. Understanding the net sediment transport rate in response to wave skewness/asymmetry is fundamental to a better prediction of sediment transport in regional scale morphodynamic models. In this study, we used an Euler-Lagrange two-phase model to study sheet flow transport of coarse sand under oscillatory flows subject to velocity/acceleration skewness.

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Multi-Phase Model on Sediment Transport in Sheet-Flow Regime Under Oscillatory Flow

Coastal Engineering in Japan ◽

10.1080/05785634.1995.11952813 ◽

1995 ◽

Vol 38 (2) ◽

pp. 157-178 ◽

Cited By ~ 30

Author(s):

Liya Li ◽

Masaki Sawamoto

Keyword(s):

Sediment Transport ◽

Flow Regime ◽

Oscillatory Flow ◽

Phase Model ◽

Sheet Flow ◽

Multi Phase

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Multi-dimensional rheology-based two-phase model for sediment transport and applications to sheet flow and pipeline scour

Physics of Fluids ◽

10.1063/1.4948987 ◽

2016 ◽

Vol 28 (5) ◽

pp. 053305 ◽

Cited By ~ 32

Author(s):

Cheng-Hsien Lee ◽

Ying Min Low ◽

Yee-Meng Chiew

Keyword(s):

Sediment Transport ◽

Phase Model ◽

Sheet Flow ◽

Two Phase

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Numerical Study for Near-Bed Variables in Velocity-Skewed Oscillatory Sheet Flow Transport

Mathematical Problems in Engineering ◽

10.1155/2017/2614943 ◽

2017 ◽

Vol 2017 ◽

pp. 1-10

Author(s):

Xin Chen ◽

Zichao Zhang ◽

Yong Li ◽

Xiaoyan Shi

Keyword(s):

Sediment Concentration ◽

Sediment Flux ◽

Phase Model ◽

Phase Lag ◽

Bed Sediment ◽

Sheet Flow ◽

Fall Velocity ◽

Two Phase ◽

Sediment Size ◽

Flow Transport

The near-bed sediment concentration and vertical sediment flux are important in sediment transport mechanics, but they are known much less than the horizontal sediment flux, especially for fine sediment in unsteady flows. A developed two-phase model is applied to study the near-bed sediment concentration, vertical sediment flux, and the relevant total sediment amount for the velocity-skewed oscillatory sheet flow transport. With the sediment concentration hindered fall velocity, the classical reference concentration formulas conducted by Engelund and Fredsoe (1976) and Zyserman and Fredsoe (1994) are utilized for the comparison with the two-phase model and illustration of the phase-lag and sediment size effects in near-bed sediment concentration and vertical sediment flux. The concentration and vertical flux predicted by the two-phase model agree well with experimental data and are better than empirical formulas. Furthermore, the sediment size effect for pick-up flux function over starved bed is shown to be quite different from that containing sufficient sediment in oscillatory flows.

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