Computational Simulation of Aeolian Saltation
نویسندگان
چکیده
We reveal that the transition in the saturated flux for aeolian saltation is generically discontinuous by explicitly simulating particle motion in turbulent flow in two dimensions. The discontinuity is followed by a coexistence interval with two metastable solutions. We found also that the mere presence of mid-air collisions, surprisingly, enhances the saturated flux, which has a peak for an intermediate restitution coefficient of 0.65.
منابع مشابه
The apparent roughness of a sand surface blown by wind from an analytical model of saltation
We present an analytical model of aeolian sand transport. The model quantifies the momentum transfer from the wind to the transported sand by providing expressions for the thickness of the saltation layer and the apparent surface roughness. These expressions are derived from basic physical principles and a small number of assumptions. The model further predicts the sand transport rate (mass flu...
متن کاملWind-invariant saltation heights imply linear scaling of aeolian saltation flux with shear stress
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 کاملSurface drag
I will deiscuss the drag of particles on granular surfaces by a fluid. I will present simulations using FLUENT of Aeolian saltation under Earth and Mars conditions obtaining among others the static and dynamic threshold shear and the height of the saltation layer as function of the wind strength. A universal quadratic increase of the saturated flux as function of the difference from the thresho...
متن کاملTwo-Species Continuum Model for Aeolian Sand Ripples
We formulate a continuum model for aeolian sand ripples consisting of two species of grains: a lower layer of relatively immobile clusters, with an upper layer of highly mobile grains moving on top. We predict analytically the ripple wavelength, initial ripple growth rate, and threshold saltation flux for ripple formation. Numerical simulations show the evolution of realistic ripple profiles fr...
متن کاملDynamics 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 کامل