Physical theory for near-bed turbulent particle suspension capacity
The inability to capture the physics of solid-particle suspension in turbulent fluids in simple formulas is holding back the application of multiphase fluid dynamics techniques to many practical problems in nature and society involving particle suspension. We present a force balance approach to...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-05-01
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| Series: | Earth Surface Dynamics |
| Online Access: | http://www.earth-surf-dynam.net/5/269/2017/esurf-5-269-2017.pdf |
| Summary: | The
inability to capture the physics of solid-particle suspension in turbulent
fluids in simple formulas is holding back the application of multiphase fluid
dynamics techniques to many practical problems in nature and society
involving particle suspension. We present a force balance approach to
particle suspension in the region near no-slip frictional boundaries of
turbulent flows. The force balance parameter Γ contains gravity and
buoyancy acting on the sediment and vertical turbulent fluid forces; it
includes universal turbulent flow scales and material properties of the fluid
and particles only. Comparison to measurements shows that Γ = 1 gives
the upper limit of observed suspended particle concentrations in a broad
range of flume experiments and field settings. The condition of Γ > 1 coincides with the complete suppression of coherent
turbulent structures near the boundary in direct numerical simulations of
sediment-laden turbulent flow. Γ thus captures the maximum amount of
sediment that can be contained in suspension at the base of turbulent flow,
and it can be regarded as a suspension capacity parameter. It can be applied
as a simple concentration boundary condition in modelling studies of the
dispersion of particulates in environmental and man-made flows. |
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| ISSN: | 2196-6311 2196-632X |