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Tholen K, Pähtz T, Kamath S, Parteli EJR, Kroy K. Anomalous Scaling of Aeolian Sand Transport Reveals Coupling to Bed Rheology. PHYSICAL REVIEW LETTERS 2023; 130:058204. [PMID: 36800459 DOI: 10.1103/physrevlett.130.058204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 01/05/2023] [Indexed: 06/18/2023]
Abstract
Predicting transport rates of windblown sand is a central problem in aeolian research, with implications for climate, environmental, and planetary sciences. Though studied since the 1930s, the underlying many-body dynamics is still incompletely understood, as underscored by the recent empirical discovery of an unexpected third-root scaling in the particle-fluid density ratio. Here, by means of grain-scale simulations and analytical modeling, we elucidate how a complex coupling between grain-bed collisions and granular creep within the sand bed yields a dilatancy-enhanced bed erodibility. Our minimal saltation model robustly predicts both the observed scaling and a new undersaturated steady transport state that we confirm by simulations for rarefied atmospheres.
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Affiliation(s)
- Katharina Tholen
- Institute for Theoretical Physics, Leipzig University, Postfach 100920, 04009 Leipzig, Germany
| | - Thomas Pähtz
- Donghai Laboratory, 316021 Zhoushan, China
- Institute of Port, Coastal and Offshore Engineering, Ocean College, Zhejiang University, 316021 Zhoushan, China
| | - Sandesh Kamath
- Faculty of Physics, University of Duisburg-Essen, Lotharstraße 1-21, D-47057 Duisburg, Germany
| | - Eric J R Parteli
- Faculty of Physics, University of Duisburg-Essen, Lotharstraße 1-21, D-47057 Duisburg, Germany
| | - Klaus Kroy
- Institute for Theoretical Physics, Leipzig University, Postfach 100920, 04009 Leipzig, Germany
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Ralaiarisoa JL, Besnard JB, Furieri B, Dupont P, Ould El Moctar A, Naaim-Bouvet F, Valance A. Transition from Saltation to Collisional Regime in Windblown Sand. PHYSICAL REVIEW LETTERS 2020; 124:198501. [PMID: 32469561 DOI: 10.1103/physrevlett.124.198501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 02/18/2020] [Accepted: 04/20/2020] [Indexed: 06/11/2023]
Abstract
We report experiments on windblown sand that highlight a transition from saltation to collisional regime above a critical dimensionless mass flux or Shields number. The transition is first seen through the mass flow rate Q, which deviates from a linear trend with the Shields number and seems to follow a quadratic law. Other physical evidences confirm the change of the transport properties. In particular, the particle velocity and the height of the transport layer increases with increasing Shields number in the collisional regime while the latter are invariant with the wind strength in the saltation regime. Discrete numerical simulations support the experimental findings and ascertain that mid-air collisions are responsible for the change of transport regime.
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Affiliation(s)
- J-L Ralaiarisoa
- Univ Rennes, CNRS, Institut de Physique de Rennes, UMR 6251, 35 042 Rennes, France
- Univ. Grenoble Alpes, INRAE, UR ETNA, 38000 Grenoble, France
| | - J-B Besnard
- Univ Rennes, CNRS, Institut de Physique de Rennes, UMR 6251, 35 042 Rennes, France
- Univ Rennes, INSA Rennes, LGCGM, 35 043 Rennes, France
| | - B Furieri
- Universidade Federal do Espírito Santo, DEA, 29060-970 Vitória, ES, Brazil
| | - P Dupont
- Univ Rennes, INSA Rennes, LGCGM, 35 043 Rennes, France
| | - A Ould El Moctar
- Univ Nantes, Laboratoire Thermique et Energie, UMR 6607, 44306 Nantes Cedex, France
| | - F Naaim-Bouvet
- Univ. Grenoble Alpes, INRAE, UR ETNA, 38000 Grenoble, France
| | - A Valance
- Univ Rennes, CNRS, Institut de Physique de Rennes, UMR 6251, 35 042 Rennes, France
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Sarafrazi V, Reza Talaee M. Numerical simulation of sand transfer in wind storm using the Eulerian-Lagrangian two-phase flow model. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2019; 42:45. [PMID: 30980336 DOI: 10.1140/epje/i2019-11809-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Accepted: 03/11/2019] [Indexed: 06/09/2023]
Abstract
In this paper a two-dimensional gas-solid flow model is used to investigate the sand particles carrying velocity of the Iran eastern desert area around the railway track as a case study. Reynolds-averaged Navier-Stokes (RANS) equations and Discrete Phase Method (DPM) are used to simulate the characteristic movement of sand particles in wind flow. A random sample is gathered from the sand near the railway in Iran deserts. The sample is classified based on weight and diameter according to AASHTOO T27 and sand distribution is determined. Using simulations, the carrying velocity of sand in each category in wind storm is determined. Finally, the sand distribution of the sample is imported to the model by the Rosin-Rummler dissipation model. The behavior of sand particles in storm considering wind blowing scheme of desert is studied parametrically. The results can be used for estimating the sand mitigation of a special desert and land desertification control around railway tracks.
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Affiliation(s)
- Vahid Sarafrazi
- School of Railway Engineering, Iran University of Science and Technology (IUST), 16846-13114, Tehran, Iran
| | - Mohammad Reza Talaee
- School of Railway Engineering, Iran University of Science and Technology (IUST), 16846-13114, Tehran, Iran.
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Lämmel M, Kroy K. Analytical mesoscale modeling of aeolian sand transport. Phys Rev E 2018; 96:052906. [PMID: 29347761 DOI: 10.1103/physreve.96.052906] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Indexed: 11/07/2022]
Abstract
The mesoscale structure of aeolian sand transport determines a variety of natural phenomena studied in planetary and Earth science. We analyze it theoretically beyond the mean-field level, based on the grain-scale transport kinetics and splash statistics. A coarse-grained analytical model is proposed and verified by numerical simulations resolving individual grain trajectories. The predicted height-resolved sand flux and other important characteristics of the aeolian transport layer agree remarkably well with a comprehensive compilation of field and wind-tunnel data, suggesting that the model robustly captures the essential mesoscale physics. By comparing the predicted saturation length with field data for the minimum sand-dune size, we elucidate the importance of intermittent turbulent wind fluctuations for field measurements and reconcile conflicting previous models for this most enigmatic emergent aeolian scale.
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Affiliation(s)
- Marc Lämmel
- Institut für Theoretische Physik, Universität Leipzig, Postfach 100920, 04009 Leipzig, Germany
| | - Klaus Kroy
- Institut für Theoretische Physik, Universität Leipzig, Postfach 100920, 04009 Leipzig, Germany
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Martin RL, Kok JF. Wind-invariant saltation heights imply linear scaling of aeolian saltation flux with shear stress. SCIENCE ADVANCES 2017; 3:e1602569. [PMID: 28630907 PMCID: PMC5462498 DOI: 10.1126/sciadv.1602569] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 04/21/2017] [Indexed: 06/08/2023]
Abstract
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, from three new field sites and three published studies, showing that characteristic saltation layer heights remain approximately constant with shear velocity, in agreement with recent wind tunnel studies. These results support the assumption of constant particle speeds in recent models predicting linear scaling of saltation flux with shear stress. In contrast, our results refute widely used older models that assume that particle speed increases with shear velocity, thereby predicting nonlinear 3/2 stress-flux scaling. This conclusion is further supported by direct field measurements of saltation flux versus shear stress. Our results thus argue for adoption of linear saltation flux laws and constant saltation trajectories for modeling saltation-driven aeolian processes on Earth, Mars, and other planetary surfaces.
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Berger KJ, Hrenya CM. Impact of a binary size distribution on particle erosion due to an impinging gas plume. AIChE J 2015. [DOI: 10.1002/aic.15087] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kyle J. Berger
- Dept. of Chemical and Biological Engineering; University of Colorado; Boulder CO 80309
| | - Christine M. Hrenya
- Dept. of Chemical and Biological Engineering; University of Colorado; Boulder CO 80309
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Kang L, Zhao G, Zou X, Zhang C, Cheng H. An improved particle counting method for particle volume concentration in aeolian sand transport. POWDER TECHNOL 2015. [DOI: 10.1016/j.powtec.2015.04.056] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Abstract
Close to the onset of Aeolian particle transport through saltation we find in wind tunnel experiments a regime of discontinuous flux characterized by bursts of activity. Scaling laws are observed in the time delay between each burst and in the measurements of the wind fluctuations at the fluid threshold Shields number θc. The time delay between each burst decreases on average with the increase of the Shields number until sand flux becomes continuous. A numerical model for saltation including the wind-entrainment from the turbulent fluctuations can reproduce these observations and gives insight about their origin. We present here also for the first time measurements showing that with feeding it becomes possible to sustain discontinuous flux even below the fluid threshold.
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Varsakelis C, Papalexandris MV. Numerical simulation of subaqueous chute flows of granular materials. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2015; 38:125. [PMID: 25985944 DOI: 10.1140/epje/i2015-15040-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 03/16/2015] [Accepted: 03/17/2015] [Indexed: 06/04/2023]
Abstract
In this paper we report on numerical studies of unsteady, gravity-driven flow of a subaqueous erodible granular bed on an inclined plane. According to our simulations, the evolution of the flow can be partitioned in three phases. In the first phase, due to the onset of an interfacial instability, the material interface deforms into a series of long waves. In the second phase, these waves are transformed to skewed vortex ripples that grow in time and eventually coalesce. The computed wavelengths of these ripples are in good agreement with previously reported experimental measurements. In the third phase of the flow evolution, the high fluid velocities wash out the vortex ripples and a layer of rapidly moving particles is formed at the material interface. The predicted granular velocities comprise two segments: a concave one at the vicinity of the material interface, where the maximum is attained, followed by a slightly convex one, where they decrease monotonically to zero. The same trend has been reported in experimental results for the corresponding steady flows. Finally, we investigate via a parametric study the effect of the configuration stresses, which represent contact forces between grains. As it turns out, such stresses have a stabilizing effect, in the sense that increasing their magnitude inhibits the formation of vortex ripples.
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Affiliation(s)
- C Varsakelis
- Institute of Mechanics, Materials and Civil Engineering, Université catholique de Louvain, B1348, Louvain-la-Neuve, Belgium,
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Wang ZT, Zhang CL, Wang HT. Intermittency of aeolian saltation. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2014; 37:126. [PMID: 25528744 DOI: 10.1140/epje/i2014-14126-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Revised: 11/29/2014] [Accepted: 12/01/2014] [Indexed: 06/04/2023]
Abstract
Saltation motion of sand grains in a steady wind was measured using a high-speed camera at very high frequency in a wind tunnel. A Heaviside-type function was defined to quantificationally describe an inherent property of saltation, i.e. intermittency. Kurtosis and periodicity of state function are statistical manifestations of intermittency. In addition, the strong autocorrelation of time series of volume concentration clearly confirms that saltation is not a completely random process at the timescale of subsecond. Formation mechanism, especially turbulent structures responsible for intermittent saltation, remains to be revealed from the viewpoint of classical mechanics.
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Affiliation(s)
- Zhen-Ting Wang
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, 100875, Beijing, P.R. China,
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Abstract
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 out to be driven by resonant grain trajectories, whose length is close to a ripple wavelength and whose splash leads to a mass displacement toward the ripple crests. The pattern selection results from a compromise between this destabilizing mechanism and a diffusive downslope transport which stabilizes small wavelengths. The initial wavelength is set by the ratio of the sediment flux and the erosion/deposition rate, a ratio which increases linearly with the wind velocity. We show that this scaling law, in agreement with experiments, originates from an interfacial layer separating the saltation zone from the static sand bed, where momentum transfers are dominated by midair collisions. Finally, we provide quantitative support for the use of the propagation of these ripples as a proxy for remote measurements of sediment transport.
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Huang H, Bo T, Zheng X. Numerical modeling of wind-blown sand on Mars. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2014; 37:36. [PMID: 25236498 DOI: 10.1140/epje/i2014-14080-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 03/02/2014] [Accepted: 08/13/2014] [Indexed: 06/03/2023]
Abstract
Recent observation results show that sand ripples and dunes are movable like those on Earth under current Martian climate. And the aeolian process on Mars therefore is re-attracting the eyes of scientific researchers in different fields. In this paper, the spatial and temporal evolution of wind-blown sand on Mars is simulated by the large-eddy simulation method. The simulations are conducted under the conditions of both friction wind speed higher and lower than the "fluid threshold", respectively. The fluid entrainment of the sand particles, the processes among saltation sand particles and sand bed, and the negative feedback of sand movement to flow field are considered. Our results show that the "overshoot" phenomenon also exists in the evolution of wind-blown sand on Mars both temporally and spatially; impact entrainment affects the sand transport rate on Mars when the wind speed is smaller or larger than the fluid threshold; and both the average saltation length and height are one order of magnitudes larger than those on Earth. Eventually, the formulas describing the sand transport rate, average saltation length and height on Mars are given, respectively.
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Affiliation(s)
- HaoJie Huang
- Key Laboratory of Mechanics on Environment and Disaster in Western China, Ministry of Education, Lanzhou University, 730000, Lanzhou, China
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13
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Abstract
Saltation is an important geological process and the primary source of atmospheric mineral dust aerosols. Unfortunately, no studies to date have been able to precisely reproduce the saltation process because of the simplified theoretical models used. For example, sand particles in most of the existing wind sand movement models are considered to be spherical, the effects of the sand shape on the structure of the wind sand flow are rarely studied, and the effect of mid-air collision is usually neglected. In fact, sand grains are rarely round in natural environments. In this paper, we first analyzed the drag coefficients, drag forces, and starting friction wind speeds of sand grains with different shapes in the saltation process, then established a sand saltation model that considers the coupling effect between wind and the sand grains, the effect of the mid-air collision of sand grains, and the effect of the sand grain shape. Based on this model, the saltation process and sand transport rate of non-spherical sand particles were simulated. The results show that the sand shape has a significant impact on the saltation process; for the same wind speed, the sand transport rates varied for different shapes of sand grains by as much as several-fold. Therefore, sand shape is one of the important factors affecting wind-sand movement.
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Affiliation(s)
- Zhengshi Wang
- Key Laboratory of Mechanics on Disaster and Environment in Western China (Lanzhou University), The Ministry of Education of China, Lanzhou, China
- Department of Mechanics, School of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, China
| | - Shan Ren
- Department of Mechanics, School of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, China
| | - Ning Huang
- Key Laboratory of Mechanics on Disaster and Environment in Western China (Lanzhou University), The Ministry of Education of China, Lanzhou, China
- Department of Mechanics, School of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, China
- * E-mail:
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Pähtz T, Parteli EJR, Kok JF, Herrmann HJ. Analytical model for flux saturation in sediment transport. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:052213. [PMID: 25353793 DOI: 10.1103/physreve.89.052213] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Indexed: 06/04/2023]
Abstract
The transport of sediment by a fluid along the surface is responsible for dune formation, dust entrainment, and a rich diversity of patterns on the bottom of oceans, rivers, and planetary surfaces. Most previous models of sediment transport have focused on the equilibrium (or saturated) particle flux. However, the morphodynamics of sediment landscapes emerging due to surface transport of sediment is controlled by situations out of equilibrium. In particular, it is controlled by the saturation length characterizing the distance it takes for the particle flux to reach a new equilibrium after a change in flow conditions. The saturation of mass density of particles entrained into transport and the relaxation of particle and fluid velocities constitute the main relevant relaxation mechanisms leading to saturation of the sediment flux. Here we present a theoretical model for sediment transport which, for the first time, accounts for both these relaxation mechanisms and for the different types of sediment entrainment prevailing under different environmental conditions. Our analytical treatment allows us to derive a closed expression for the saturation length of sediment flux, which is general and thus can be applied under different physical conditions.
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Affiliation(s)
- Thomas Pähtz
- Ocean College, Zhejiang University, 310058 Hangzhou, China and State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, 310012 Hangzhou, China
| | - Eric J R Parteli
- Institute for Multiscale Simulation, Universität Erlangen-Nürnberg, Nägelsbachstraße 49b, 91052 Erlangen, Germany
| | - Jasper F Kok
- Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, California 90095, USA
| | - Hans J Herrmann
- Departamento de Física, Universidade Federal do Ceará, 60451-970 Fortaleza, Ceará, Brazil and Computational Physics, IfB, ETH Zürich, Schafmattstraße 6, 8093 Zürich, Switzerland
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Abstract
We examine the validity of Hertz's linear elastic theory for central collisions of spheres using a viscoelastic model. This model explains why Hertz's theory is accurate in predicting the collision time and maximum contact area even when 40% of the kinetic energy is lost due to viscous dissipation. The main reason is that both the collision time and maximum contact area have a very weak dependence on the impact velocity. Moreover, we show that colliding objects exhibit an apparent size-dependent yield strength, which results from larger objects dissipating less energy at a given impact velocity.
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Affiliation(s)
- Andong He
- Yale University, New Haven, CT 06520, USA.
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Zhang H, Zheng XJ, Bo TL. Electric fields in unsteady wind-blown sand. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2014; 37:13. [PMID: 24574056 DOI: 10.1140/epje/i2014-14013-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 12/13/2013] [Accepted: 02/10/2014] [Indexed: 06/03/2023]
Abstract
The electrification of wind-blown sand has been widely confirmed by field and wind-tunnel measurements. It plays an important role in the lifting and transport of sand particles. In this study we investigated the behavior of electric fields in unsteady saltation by adopting periodic variation wind sequences. The influence of electric fields on sand transport rate was also discussed. The results show that both horizontal and vertical electric fields exist in unsteady saltation, and the transport rate in unsteady saltation is less than that in steady saltation. An interesting result is that the directions of vertical electric field fluctuate upward and downward-pointing with time in the unsteady saltation. This provides a possible explanation for the bipolar pattern of the vertical electric field in wind-blown sand.
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Affiliation(s)
- Huan Zhang
- Key Laboratory of Mechanics on Western Disaster and Environment, Lanzhou University, 730000, Lanzhou, China
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Wang ZT, Zhang CL, Wang HT. Forces on a saltating grain in air. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2013; 36:112. [PMID: 24091939 DOI: 10.1140/epje/i2013-13112-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 09/06/2013] [Indexed: 06/02/2023]
Abstract
A wind tunnel experiment was performed to measure the trajectories of individual sand grains. Then, the acceleration given by the numerical differentiation was used to assess the relative importance of different external forces on a saltating sand grain in air. It is reconfirmed that the gravitational force and drag are the most important to grain motion. The lift also has certain influence. However, the present research does not support that the electrostatic force is significant.
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Affiliation(s)
- Zhen-Ting Wang
- State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, 100875, Beijing, P.R. China,
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18
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Sand collisions kick up storms. Nature 2013. [DOI: 10.1038/500256a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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