Modern Mars' geomorphological activity, driven by wind, frost, and gravity

Geomorphology, Journal Year: 2021, Volume and Issue: 380, P. 107627 - 107627

Published: Jan. 30, 2021

Language: Английский

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Threshold constraints on the size, shape and stability of alluvial rivers

Nature Reviews Earth & Environment, Journal Year: 2022, Volume and Issue: 3(6), P. 406 - 419

Published: May 3, 2022

Language: Английский

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Particle resuspension: Challenges and perspectives for future models

Physics Reports, Journal Year: 2023, Volume and Issue: 1007, P. 1 - 98

Published: Jan. 11, 2023

Language: Английский

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Unification of Aeolian and Fluvial Sediment Transport Rate from Granular Physics

Physical Review Letters, Journal Year: 2020, Volume and Issue: 124(16)

Published: April 20, 2020

One of the physically least understood characteristics geophysical transport sediments along sediment surfaces is well-known experimental observation that rate Q linearly dependent on fluid shear stress τ applied onto surface in air, but nonlinearly water. Using simulations for a wide range driving conditions, we show scaling depends manner which kinetic fluctuation energy transported particles dissipated: via predominantly drag and quasistatic contacts (linear) versus collisional (nonlinear). We use this finding to derive law (asymptotically Q∼τ2) simultaneous agreement with measurements water air streams.Received 25 November 2019Revised 29 January 2020Accepted February 2020DOI:https://doi.org/10.1103/PhysRevLett.124.168001© 2020 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasGranular flowsParticle-laden flowsScaling laws complex systemsSediment transportPhysical SystemsGranular fluidsGranular gasesTechniquesCoarse grainingMolecular dynamicsPolymers & Soft MatterFluid DynamicsInterdisciplinary Physics

Language: Английский

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A lower-than-expected saltation threshold at Martian pressure and below

Proceedings of the National Academy of Sciences, Journal Year: 2021, Volume and Issue: 118(5)

Published: Jan. 28, 2021

Aeolian sediment transport is observed to occur on Mars as well other extraterrestrial environments, generating ripples and dunes Earth. The search for terrestrial analogs of planetary bedforms, environmental simulation experiments able reproduce their formation in conditions, are powerful ways question our understanding geomorphological processes toward unusual conditions. Here, we perform laboratory a closed-circuit wind tunnel placed vacuum chamber operated at extremely low pressures show that Martian conditions belong previously unexplored saltation regime. threshold speed required initiate only quantitatively predicted by state-of-the art models up density ratio between grain air [Formula: see text] but unexpectedly falls much lower values higher ratios. In contrast, impact ripples, whose emergence continuously the granular bed over whole pressure range investigated, display characteristic wavelength propagation velocity essentially independent pressure. A comparison these findings with existing suggests Reynolds number high grain-to-fluid may be dominated collective effects associated inertia collisional layer.

Language: Английский

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Microplastic and natural sediment in bed load saltation: Material does not dictate the fate

Water Research, Journal Year: 2023, Volume and Issue: 243, P. 120329 - 120329

Published: July 8, 2023

Microplastic (MP) pollution is a well document threat to our aquatic and terrestrial ecosystems, however, the mechanisms by which MPs are transported in river flows still unknown. The transport of natural sediment could be somewhat comparable, as particles similar size. However, it unknown how lower density MPs, their shape different material properties impact dynamics. To answer this, novel laboratory experiments on bed load saltation dynamics an open-channel flow, using high-speed camera imaging detection 11,035 individual events were used identify similarities differences between spherical sediments transport. tested varied terms size (density elasticity). Our analysis shows that Rouse number accurately describes length, height, velocity collision angles equally for both sediments. Through statistical inference, distribution functions trajectory characteristics analogous with only one experiment (1.4% cases) differing from all other plastic experiments. Similarly, nine (9.3% showed differed those Differences observed restitution become negligible overall turbulence overcomes kinetic energy lost at particle-bed impact, keeps particle motion independent impact. Overall, MP behave similarly environments under examined experimental conditions. This significant because there established body knowledge can serve foundation study

Language: Английский

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Study of Aerodynamic Grain Entrainment in Aeolian Transport

Geophysical Research Letters, Journal Year: 2020, Volume and Issue: 47(11)

Published: April 29, 2020

Abstract Aeolian transport controls landform formations on Earth and other planets crucially affects the atmospheric system. With elaborate wind tunnel measurements, we find that aerodynamic entrainment rate follows a yet unreported exponential increase in intermittent regime only complies with expected linear law for condition of continuous entrainment. Subsequently, propose model accounting effects turbulence based distribution local shear stress to describe experimental results. We also provide evidence can be an efficient way directly induce horizontal grain comparable steady saturated saltation unsaturated conditions should not ignored. Our findings substantially modify present interpretation surface erosion bear thus important consequences future soil protection techniques.

Language: Английский

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Modeling Snow Saltation: The Effect of Grain Size and Interparticle Cohesion

Journal of Geophysical Research Atmospheres, Journal Year: 2021, Volume and Issue: 127(1)

Published: Dec. 10, 2021

Abstract The surface of the Earth is snow‐covered at least seasonally over large areas. This snow highly dynamic, particularly under influence strong winds. motion particles driven by wind not only changes cover but has important consequences for atmosphere in that it adds mass and moisture extracts heat. Large scale meteorological climatological models neglect these dynamics or produce conflicting results from too simplified process representation. With recent progress detailed understanding saltation process, particular with respect to sand saltation, advancement numerical models, we can systematically investigate properties on saltation. contribution uses a Eddy Simulation model full particle how cohesion size distribution total flux. reproduces some known characteristics system such as focus point constant near speed. An interesting result grain heterogeneity increase overall flux high friction velocities. Moreover, agree reasonably well simulations given bed characteristics, while others clearly do not. These are valid continuous intermittent which often occurs nature, needs further investigation. In order successfully parameterize must be made correctly representing cohesion.

Language: Английский

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Prediction of bedload transport rate using a block combined network structure

Hydrological Sciences Journal, Journal Year: 2021, Volume and Issue: 67(1), P. 117 - 128

Published: Nov. 9, 2021

Modularity as a system of separate and independent sub-tasks is the appropriate way to improve performance artificial neural network (ANN) models in hydrological processes. Using this approach, block combined (BCNN) structure incorporated with genetic algorithm (GA) an additional decision suggested study. The optimum topology embedded networks each was detected using vector-based method subjected different internal characteristics. This model then applied on 879 bedload datasets, considering velocity, discharge, mean grain size, slope, depth inputs over streams Idaho, USA. correct classification rate predicted BCNN (89.77%) showed superior accuracy compared other ANNs, empirical models. Results computed error metrics confusion matrixes also demonstrated outstanding progress relative We show that new level could effectively be adopted for prediction purposes.

Language: Английский

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The role of increasing riverbank vegetation density on flow dynamics across an asymmetrical channel

Environmental Fluid Mechanics, Journal Year: 2021, Volume and Issue: 21(3), P. 643 - 666

Published: April 15, 2021

Abstract Over the last two decades, role of vegetation in environmental and ecological restoration surface water bodies has received much attention. In this context, momentum exchange between flow through main channel riparian zone is a key mechanism. The primary goal study to investigate bank density on dynamics across whole channel. This experimental presents major findings from series measurements having sloping with at varying densities. experiments are conducted under same, uniform fixed bed conditions, for range six linear rectilinear arrangements incremental streambank A set ten velocity profiles obtained test cross-section channel, including riverbank, each density. These analyzed derive roughness coefficients, which related bulk velocities riverbank discuss redistribution velocities. An approximate doubling estimates time-averaged boundary shear stress observed case no dense vegetation, enable further discussing implications stability material. It found that arrangement, addition density, can have strong impact modifying mean low densities ( φ < 0.6%). Highlights Flow measured vegetated riverbank. As stem increases, increases while decreases. arrangement be as important field Bed stresses estimated increase reducing stream’s surface.

Language: Английский

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