The fluctuation energy balance in non-suspended fluid-mediated particle transport

Abstract

Here we compare two extreme regimes of non-suspended fluid-mediated particle transport, transport in light and heavy fluids ("saltation" and "bedload", respectively), regarding their particle fluctuation energy balance. From direct numerical simulations, we surprisingly find that the ratio between collisional and fluid drag dissipation of fluctuation energy is significantly larger in saltation than in bedload, even though the contribution of interparticle collisions to transport of momentum and energy is much smaller in saltation due to the low concentration of particles in the transport layer. We conclude that the much higher frequency of high-energy particle-bed impacts ("splash") in saltation is the cause for this counter-intuitive behavior. Moreover, from a comparison of these simulations to Particle Tracking Velocimetry measurements which we performed in a wind tunnel under steady transport of fine and coarse sand, we find that turbulent fluctuations of the flow produce particle fluctuation energy at an unexpectedly high rate in saltation even under conditions for which the effects of turbulence are usually believed to be small.

References in corpus (9)

• The physics of wind-blown sand and dust
• Numerical simulation of turbulent sediment transport, from bed load to saltation
• Direct numerical simulations of aeolian sand ripples
• Midair collisions enhance saltation
• Flux saturation length of sediment transport
• The apparent roughness of a sand surface blown by wind from an analytical model of saltation
• Jump at the onset of saltation
• A two-species continuum model for aeolian sand transport
• Analytical model for flux saturation in sediment transport

Cited by in corpus (7)

• Unification of Aeolian and Fluvial Sediment Transport Rate from Granular Physics
• The Cessation Threshold of Nonsuspended Sediment Transport Across Aeolian and Fluvial Environments
• Fluid forces or impacts: What governs the entrainment of soil particles in sediment transport mediated by a Newtonian fluid?
• Discrete Element Method simulations of the saturation of aeolian sand transport
• Universal friction law at granular solid-gas transition explains scaling of sediment transport load with excess fluid shear stress
• Single-dopant band bending fluctuations in MoSe${}_2$ measured with electrostatic force microscopy
• Anomalous Scaling of Aeolian Sand Transport Reveals Coupling to Bed Rheology