Geophysical mechanisms governing particle transport by wind

风控制粒子传输的地球物理机制

• 批准号: RGPIN-2019-03969
• 负责人: McKennaNeuman, Cheryl
• 金额: $ 3.13万
• 依托单位: Trent University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=764542
• 关键词: Geophysical; mechanisms; governing; particle; transport

Wind is ubiquitous at Earth's surface, as well as on other planetary bodies such as Mars, Venus and Titan. Where any source of loose particles exists, the fluid drag of the wind may entrain and carry some fraction of these particles over distances varying from just a few millimeters to several meters and ultimately in the case of dust in long-term suspension, over thousands of kilometers. As such, the transport of these particles may affect air quality, visibility, the absorption and transmission of solar radiation, climate, soil fertility, and through deposition, surface topography (e.g. dunes).       While technically any form of particle can be transported in an airflow, my long-term research program funded by the NSERC Discovery Grant program is primarily focused upon natural sedimentary particles. My principal methodological approach is founded on the use of a boundary-layer wind tunnel to study the geophysical processes that govern particulate matter (PM) transport in air flows. Less than a half dozen such facilities in the world are typically engaged in work of this type at any given point in time. The Trent Environmental Wind Tunnel (TEWT) is distinguished as supporting one of the longest standing and most continuous research programs investigating (aeolian) sedimentary processes. It also is the only one of its type to be located in an environmental chamber with full climate control down to subfreezing temperatures. Laser based technologies available within TEWT include Particle Tracking Velocimetry (PTV) for investigating particle dynamics; Laser Doppler Anemometry (LDA) for sampling the properties of the airflow structure and particle kinetic; and LiDAR for mapping the surface morphometry.       The proposed work will use the leading-edge technologies available within TEWT to investigate: i) the dynamics of discrete particle impacts and ejections during their transport across wet and frozen sedimentary bed surfaces, ii) particle impact, splash, creep and segregation during the inception, growth and migration of ballistic ripples as found on a range of planetary surfaces, iii) the role of turbulence generation in dust emission and dispersion, and iv) the role of aggregate disintegration in dust generation. Each of these studies will increase understanding of the geophysical system, provide direct measurements for the parameterization and calibration of various sediment transport and dust emission models, and may ultimately lead to improvements in practices that aim to mitigate wind erosion and improve air quality. Training will be provided for six graduate students (2 PhD and 4 MSc) and five senior undergraduate thesis students, who will undertake this work and contribute to its dissemination through conference presentations and publication.

风在地球表面无处不在，在火星、金星和土卫六等其他行星上也是如此。在存在任何松散颗粒来源的地方，风的流体阻力可能会卷起并携带这些颗粒中的一小部分，距离从几毫米到几米不等，最终对于长期悬浮的尘埃来说，可能会超过数千公里。因此，这些颗粒的迁移可能会影响空气质量、能见度、太阳辐射的吸收和传输、气候、土壤肥力，以及通过沉积、表面地形(如沙丘)。他说，虽然从技术上讲，任何形式的颗粒都可以在气流中运输，但我由NSERC发现拨款计划资助的长期研究计划主要专注于天然沉积颗粒。我的主要方法是使用边界层风洞来研究控制空气中颗粒物(PM)传输的地球物理过程。在任何给定的时间点，世界上从事这类工作的机构通常不到六个。特伦特环境风洞(TEWT)是历史最悠久、持续时间最长的风沙沉积研究项目之一。它也是唯一一种位于完全气候控制到零下温度的环境室中的同类设备。TEWT提供的基于激光的技术包括用于研究颗粒动力学的粒子跟踪测速仪(PTV)；用于采样气流结构和颗粒运动特性的激光多普勒测速仪(LDA)；以及用于绘制表面形态测量图的激光雷达。此外，拟议的工作将使用TEWT内可用的尖端技术来研究：i)离散颗粒在湿和冻结的沉积床表面运输过程中的碰撞和抛射的动力学，ii)在一系列行星表面上发现的弹道涟漪开始、增长和迁移期间的颗粒碰撞、飞溅、蠕动和分离，iii)湍流产生在尘埃排放和扩散中的作用，以及iv)聚集解体在尘埃产生中的作用。这些研究中的每一项都将增进对地球物理系统的了解，为各种泥沙输送和粉尘排放模型的参数化和校准提供直接测量，并最终可能导致旨在减少风蚀和改善空气质量的做法的改进。将为6名研究生(2名博士和4名硕士)和5名高级本科生提供培训，他们将承担这项工作，并通过会议报告和出版促进其传播。