Particle-based simulation of Aeolian transport: Granular electrification controls on the initiation of particle motion

基于粒子的风传输模拟：颗粒带电控制粒子运动的启动

• 批准号: 348617785
• 负责人: Dr. Eric Josef Ribeiro Parteli
• 金额: --
• 依托单位: Forschungsgruppe Theoretische Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/348617785?language=en
• 关键词: Particle; based; simulation; Aeolian; transport

The overall goal of the present research programme is the development of a Discrete-Element-Method (DEM) for the particle-based simulation of Aeolian sand transport and the concatenated emission of dust aerosol particles to the atmosphere. This simulation will contribute to improving the representation of the dust cycle in climate models and is of fundamental relevance to a broad range of applications, including the coastal management, the planetary sciences and the desertification research. In the first phase of this project, we achieved a numerical tool that couples a fluid mechanics model for the turbulent wind field in the atmospheric boundary layer with granular dynamics, by considering interparticle contact and van der Waals forces. In the next phase of the project, this DEM simulation will be extended to incorporate the effect of particle-particle electrostatic interactions resulting from contact electrification (tribocharging) processes. Sand and dust storms are accompanied by electric fields of a few kV/m to several hundred kV/m. Such E-fields may significantly reduce the minimal threshold wind shear velocity for direct aerodynamic entrainment of Aeolian soil particles (Ut), thereby contributing to enhance sand transport, dune migration and dust emission rates substantially. However, predicting Ut in the presence of electric charges is challenging because it is still poorly understood how electrostatic interactions between grains in the soil affect the microscopic (particle-scale) dynamics of Aeolian sediment beds. These microscopic dynamics and their role for Ut will constitute the topic of research in the next project phase, using our DEM simulations. Wind tunnel experiments have been conducted recently at the Faculty of Physics of the University of Duisburg-Essen to estimate Ut for specific distributions of particle size and electric charges. The data from these experiments will be helpful, thus, for the validation of our model. The research proposed here will pave the way for a DEM representation of tribocharging in granular materials – a phenomenon of fundamental relevance to many areas of environmental and engineering sciences.

本研究计划的总体目标是发展一种离散元法（DEM），用于基于粒子的风沙输送和粉尘气溶胶粒子向大气的串联排放模拟。这种模拟将有助于改善气候模式中沙尘循环的表现，并对包括海岸管理、行星科学和沙漠化研究在内的广泛应用具有根本的相关性。在该项目的第一阶段，我们通过考虑颗粒间接触和范德华力，实现了将大气边界层湍流风场的流体力学模型与颗粒动力学相结合的数值工具。在项目的下一阶段，该DEM模拟将扩展到包含由接触电气化（摩擦充电）过程产生的粒子-粒子静电相互作用的影响。沙尘暴伴随着几千伏/米到几百千伏/米的电场。这样的电场可以显著降低风成土颗粒直接气动夹带的最小阈值风切变速度（Ut），从而大大增强沙粒运输、沙丘迁移和粉尘排放率。然而，在电荷存在的情况下预测Ut是具有挑战性的，因为人们对土壤中颗粒之间的静电相互作用如何影响风成沉积物床的微观（颗粒尺度）动力学仍然知之甚少。这些微观动力学及其对Ut的作用将构成下一个项目阶段的研究主题，使用我们的DEM模拟。最近，德国杜伊斯堡-埃森大学物理系进行了风洞实验，以估计粒子大小和电荷的具体分布。因此，这些实验的数据将有助于验证我们的模型。本文提出的研究将为颗粒材料中摩擦电荷的DEM表示铺平道路，这是一种与环境和工程科学许多领域基本相关的现象。