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: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=737287
• 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.

风在地球表面以及火星、金星和土卫六等其他行星上无处不在，只要存在任何松散颗粒源，风的流体阻力就可能夹带并携带这些颗粒的一部分，其距离不等。几毫米到几米，如果灰尘长期悬浮，最终会达到数千公里。因此，这些颗粒的传播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。生育力，并通过沉积，表面地形（例如沙丘）。虽然从技术上讲，任何形式的颗粒都可以在气流中传输，但我由 NSERC 发现资助计划资助的长期研究项目主要集中在自然沉积颗粒上。边界层风洞，用于研究控制气流中颗粒物 (PM) 传输的地球物理过程，世界上在任何给定时间点通常从事此类工作的此类设施都不到六座。特伦特环境风洞 (TEWT) 因其支持历史最悠久、最持续的研究（风成）沉积过程的研究项目而闻名，它也是同类类型中唯一位于完全气候控制的环境室中的风洞。 TEWT 中可用的基于激光的技术包括用于研究粒子动力学的粒子跟踪测速 (PTV) 和激光雷达 (LiDAR)；所提议的工作将使用 TEWT 中可用的前沿技术来研究：i) 离散颗粒在潮湿和冰冻的沉积床表面传输过程中的动力学，ii) 颗粒碰撞、飞溅、在一系列行星表面发现的弹道波纹的开始、增长和迁移过程中的蠕变和偏析，iii) 湍流产生在灰尘排放和扩散中的作用，以及 iv)这些研究中的每一项都将增进对地球物理系统的了解，为各种沉积物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轻风蚀和粉尘排放的实践的改进。将为六名研究生（2名博士和4名硕士）和五名高年级本科生提供培训，他们将承担这项工作并通过会议演讲和出版物为其传播做出贡献。