Particle-based simulation of aeolian sand transport: The effect of sand availability on the transport dynamics
Abstract
Aeolian sand transport is responsible for the emission of dust aerosols and plays a vital role in shaping our planet's topography. Various models have been proposed to predict the mass flux of particles in Aeolian transport over a fully erodible bed, as a function of the wind shear velocity. However, natural sand beds are often only partially erodible; since crusts, moisture, vegetation, and non-erodible elements could result in sparse rigid beds [1]. As it is difficult to accurately represent scenarios of low sand availability in theoretical models, particle-based simulations are required. Here we perform such simulations by employing the Discrete Element Method (DEM) [2,3], to investigate transitioning cases from when the bed is fully rigid, to when it becomes completely erodible. To this end, we implement an efficient description of turbulent boundary layer wind field in the open-source library LAMMPS [4], which allows us to run massively parallel DEM simulations of Aeolian sand transport. We find that the saturated sand flux depends strongly on the thickness of the mobile sand layer (hmob) over the rough non-erodible ground. Specifically, we realize here that the sand flux decreases initially with hmob up to about 2-3 particle diameters, thereafter increasing at a saddle point, while the bed becomes fully rigid [5]. We give a micro-dynamic perspective to comprehend this behavior through DEM experiments of grain-bed collisions for varying hmob. The model is further extended to Mars, which yields an expression for the Martian minimal wind shear velocity threshold for sustained transport as a function of sand availability. In summary, we convey an improved understanding of Aeolian transport dynamics as a function of the mobile sand availability. Our results are important for the reliable parameterization of soil erosion and dust emission processes in Earth system simulations, and to predict sediment flux in extra-terrestrial environments, such as Mars.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMEP022..02K
- Keywords:
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- 3322 Land/atmosphere interactions;
- ATMOSPHERIC PROCESSES;
- 3346 Planetary meteorology;
- ATMOSPHERIC PROCESSES;
- 5405 Atmospheres;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5415 Erosion and weathering;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS