Periodic saltation over hydrodynamically rough beds: aeolian to aquatic
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چکیده
منابع مشابه
Dynamics and Self-organization in Aeolian Ripples
Aeolian ripples arise instantaneously from sandy beds subjected to winds sufficient to cause saltation to surface grains. It is now widely believed that the process of ripple formation is a self-organizing phenomenon involving non-linear dynamics in the variation of flux of secondary grains that are ejected through saltation. In addition, the metric entropy and interaction matrix of the system ...
متن کاملDynamics of particles in aeolian saltation
In aeolian transport saltation is an important link by which momentum is transmitted from the air to the bed through grain impact, but momentum transfer, impact and subsequent entrainment take place in a very shallow layer at the air-bed interface with large velocity gradients. Consequently, experimental evidence on the impact-entrainment processes has been obtained from few and simplified stud...
متن کاملDirect numerical simulations of aeolian sand ripples.
Aeolian sand beds exhibit regular patterns of ripples resulting from the interaction between topography and sediment transport. Their characteristics have been so far related to reptation transport caused by the impacts on the ground of grains entrained by the wind into saltation. By means of direct numerical simulations of grains interacting with a wind flow, we show that the instability turns...
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Wind-driven sand transport generates atmospheric dust, forms dunes, and sculpts landscapes. However, it remains unclear how the flux of particles in aeolian saltation-the wind-driven transport of sand in hopping trajectories-scales with wind speed, largely because models do not agree on how particle speeds and trajectories change with wind shear velocity. We present comprehensive measurements, ...
متن کاملThe vertical variation of particle speed and flux density in aeolian saltation: measurement and modeling
Particle dynamics in aeolian saltation has been studied in a boundary layer wind tunnel above beds composed of quartz grains having diameters of either 254 μm or 320 μm. The cross section of the tunnel is 600 mm × 900 mm and its thick boundary layer allows precise estimation of the fluid friction speed. Saltation is modelled using a numerical saltation model and predicted grain speeds agree fai...
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