Analytical mesoscale modeling of aeolian sand transport

Lämmel, Marc; Kroy, Klaus

doi:10.1103/physreve.96.052906

Cited by 21 publications

(19 citation statements)

References 74 publications

(216 reference statements)

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“…The findings from collision experiments with static beds are often applied to model fluvial bedload (Berzi et al, ; Pähtz, Liu, et al, ) and aeolian saltation transport (Andreotti, ; Berzi et al, , ; Bo et al, ; Claudin and Andreotti, ; Creyssels et al, ; Huang et al, ; Jenkins et al, ; Jenkins and Valance, , ; Kok, ; Kok and Renno, ; Lämmel et al, ; Lämmel and Kroy, ; Pähtz et al, ; Pähtz, Liu, et al, ; Wang and Zheng, , ). However, if the time between successive particle‐bed impacts is too short for a bed particle to fully recover from each impact, it can accumulate more and more kinetic energy with each impact.…”

Section: The Role Of Particle Inertia In Nonsuspended Sediment Transportmentioning

confidence: 99%

“…(Note that, although Kok () does not explicitly refer to identical periodic trajectories, his mathematical treatment of the problem is equivalent to IPTMs.) However, the assumption of identical periodic particle trajectories introduces a variety of potentially major weaknesses, which has cast doubt on the reliability of IPTMs (Andreotti, ; Lämmel & Kroy, ; Pähtz & Durán, , ): In IPTMs, the particle concentration increases with elevation

z

and jumps to zero when

z

exceeds the hop height (Anderson & Hallet, ). In contrast, in real nonsuspended sediment transport, it monotonously decreases with

z

, often exponentially (e.g., Durán et al, ).…”

Section: The Role Of Particle Inertia In Nonsuspended Sediment Transportmentioning

confidence: 99%

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The Physics of Sediment Transport Initiation, Cessation, and Entrainment Across Aeolian and Fluvial Environments

Pähtz

Clark

Valyrakis

et al. 2020

Reviews of Geophysics

129

149

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Predicting the morphodynamics of sedimentary landscapes due to fluvial and aeolian flows requires answering the following questions: Is the flow strong enough to initiate sediment transport, is the flow strong enough to sustain sediment transport once initiated, and how much sediment is transported by the flow in the saturated state (i.e., what is the transport capacity)? In the geomorphological and related literature, the widespread consensus has been that the initiation, cessation, and capacity of fluvial transport, and the initiation of aeolian transport, are controlled by fluid entrainment of bed sediment caused by flow forces overcoming local resisting forces, whereas aeolian transport cessation and capacity are controlled by impact entrainment caused by the impacts of transported particles with the bed. Here the physics of sediment transport initiation, cessation, and capacity is reviewed with emphasis on recent consensus‐challenging developments in sediment transport experiments, two‐phase flow modeling, and the incorporation of granular physics' concepts. Highlighted are the similarities between dense granular flows and sediment transport, such as a superslow granular motion known as creeping (which occurs for arbitrarily weak driving flows) and system‐spanning force networks that resist bed sediment entrainment; the roles of the magnitude and duration of turbulent fluctuation events in fluid entrainment; the traditionally overlooked role of particle‐bed impacts in triggering entrainment events in fluvial transport; and the common physical underpinning of transport thresholds across aeolian and fluvial environments. This sheds a new light on the well‐known Shields diagram, where measurements of fluid entrainment thresholds could actually correspond to entrainment‐independent cessation thresholds.

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Section: The Role Of Particle Inertia In Nonsuspended Sediment Transportmentioning

confidence: 99%

z

and jumps to zero when

z

exceeds the hop height (Anderson & Hallet, ). In contrast, in real nonsuspended sediment transport, it monotonously decreases with

z

, often exponentially (e.g., Durán et al, ).…”

Section: The Role Of Particle Inertia In Nonsuspended Sediment Transportmentioning

confidence: 99%

The Physics of Sediment Transport Initiation, Cessation, and Entrainment Across Aeolian and Fluvial Environments

Pähtz

Clark

Valyrakis

et al. 2020

Reviews of Geophysics

129

149

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“…The aerodynamic threshold τ ft is deduced from Shao's work [32]. A similar method has been used in Lämmel's previous work [23], leading to convictive results. By employing it, reptation will be enhanced.…”

Section: Aerodynamic Entrainmentmentioning

confidence: 99%

3D Direct Numerical Simulation on the Emergence and Development of Aeolian Sand Ripples

et al. 2021

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A sand surface subjected to a continuous wind field exhibits a regular ripple surface. These aeolian sand ripples emerge and develop under the coupling effect between the wind field, bed surface topology, and sand particle transportation. Lots of theoretical and numerical models have been established to study the aeolian sand ripples since the last century, but none of them has the capability to directly reproduce the 3D long-term development of them. In this work, a novel numerical model with wind-blow sand and dynamic bedform is established. The emergence and long-term development of sand ripples can be obtained directly. The statistical results extracted from this model tally with those deduced from wind tunnel experiments and field observations. A simplified bed surface particle size description procedure is used in this model, which shows that the particle size distribution makes a very important contribution to sand ripples’ final steady state. This 3D bedform provides a more holistic view on the merging of small bumps before regular ripples’ formation. Analyzing the wind field results reveals an ignored development on the particle dynamic threshold during the bedform deformation.

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“…3), which connects the viscous sublayer with the log-layer. This leads to the conclusion that the viscous sublayer and buffer layer, which are usually assumed to be negligible (e.g., Kok, 2010;Berzi et al, 2016Berzi et al, , 2017Lämmel and Kroy, 2017), actually have a substantial impact on the statistical properties of saltation.…”

Section: Discussionmentioning

confidence: 99%

Aeolian sand transport: Scaling of mean saltation length and height and implications for mass flux scaling

Pähtz,

Tholen

2021

Preprint

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Wind tunnel measurements of the mean saltation length L and of different proxies of the mean saltation height H in saturated aeolian sand transport indicate that L and H are relatively insensitive to both the wind speed and grain diameter d. The latter result is currently unexplained and contradicts the theoretical prediction L ∝ H ∝ d. This prediction is based on the assumption that the characteristic velocity √ gd of bed grains ejected by the splash of an impacting grain controls the average saltation kinematics. Here, we show that a recent analytical saltation model that considers only rebounds of saltating grains, but neglects splash ejection, is consistent with the measurements. The model suggests that the buffer layer of the inner turbulent boundary layer, which connects the viscous sublayer with the log-layer, is partially responsible for the insensitivity of L and H to d. In combination, the measurements and model therefore indicate that splash ejection, though important to sustain saltation, does not significantly affect the average saltation kinematics. This finding represents a strong argument against the Ungar and Haff (1987)-scaling and in favor of the Durán et al. ( 2011)-scaling of the saturated saltation mass flux, with implications for ripple formation on Mars. Furthermore, it supports the recent controversial claim that this flux is insensitive to soil cohesion.

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Analytical mesoscale modeling of aeolian sand transport

Cited by 21 publications

References 74 publications

The Physics of Sediment Transport Initiation, Cessation, and Entrainment Across Aeolian and Fluvial Environments

The Physics of Sediment Transport Initiation, Cessation, and Entrainment Across Aeolian and Fluvial Environments

3D Direct Numerical Simulation on the Emergence and Development of Aeolian Sand Ripples

Aeolian sand transport: Scaling of mean saltation length and height and implications for mass flux scaling

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