Sheet flow
Definition of Sheet flow:
Sheet-flow sediment transport refers to transport of sandy sediments as a fluidized thin surface layer (thickness of ten to a few tens of grains).
This is the common definition for Sheet flow, other definitions can be discussed in the article
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Notes
Sheet flow is a particular form of bedload sediment transport in which the seabed is flattened and the top soil layer is fluidized. Sheet flow transport occurs when the seabed is subjected to high shear stresses, especially shear stresses generated by strong wave action (wave orbital velocity greater than 1 m/s). In the sheet-flow layer, continuous contacts between sand grains create an intergranular stress. This stress decreases the velocity in the sheet-flow layer to about one half the velocity in the top layer. The sediment concentration in the sheet-flow layer is in the order of 100 to 1000 kg/m3.
The formation of a sheet flow layer is promoted by cyclic wave loading of the seabed, see Wave-induced soil liquefaction.
Flume experiments[1] suggest that the maximum wave-generated sheet-flow layer thickness [math]\delta_{s, max}[/math] depends linearly on the maximum bed shear stress [math]\tau_{b,max}[/math],
[math]\delta_{s, max} = \Lambda \Large\frac{\tau_{b, max}}{g \Delta \rho} , [/math]
where [math]\Delta \rho[/math] is the density difference between sediment and seawater, [math]g[/math] the gravitational acceleration and [math]\Lambda[/math] a coefficient with values in the range 10-35.
Related articles
References
- ↑ Mieras, R.S., Puleo, J.A., Anderson, D., Cox, D.T. and Hsu, T.-J. 2017. Large-scale experimental observations of sheet flow on a sandbar under skewed-asymmetric waves, J. Geophys. Res. Oceans 122: 5022–5045
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