Collaborative Research: Aeolian Grain Entrainment Over Flexible Vegetation Canopies: Theoretical Models, Laboratory Experiments and Fieldwork

合作研究：灵活植被冠层的风沙颗粒夹带：理论模型、实验室实验和实地考察

• 批准号: 2327917
• 负责人: Jack Gillies
• 金额: $ 29.65万
• 依托单位: Nevada System of Higher Education, Desert Research Institute
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-11-01 至 2026-10-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2327917&HistoricalAwards=false
• 关键词: Collaborative; Research; Aeolian; Grain; Entrainment

Vegetation plays a significant role in modulating the entrainment of sediment by wind. Once entrained sand and dust particles have a crucial influence on weather and climate, air quality, landforms, and other components in the land-atmosphere system. Vast regions across the planet in areas susceptible to wind erosion have vegetation covers composed of grasses and herbs with flexible stems and blades. This type of vegetation deforms under sufficiently-high wind speeds, which alters wind-particle interactions. However, current understanding of the complex interactions remains limited, and predictive models of grain entrainment that account for the impact of canopy morphing are lacking. This project aims to elucidate the underlying physics of wind-vegetation-particle interactions for flexible canopies and develop predictive equations for aeolian grain entrainment. The model developed and validated in this research will open a pathway for understanding and predicting aeolian entrainment across a wide range of vegetation cover amounts, wind conditions, and grain properties. Results from the research endeavors will be integrated into educational activities involving K-12 education, undergraduate research, and graduate research training. The outreach activities including hands-on experiments and field trips will provide unique opportunities for attracting students, especially young women in STEM career-paths.The primary objective of this project is to combine theoretical modeling, laboratory experiments and field tests to elucidate the underlying physics of grain entrainment for flexible vegetation canopies that will aid in improving prediction of particle entrainment thresholds, concentrations and flux rates. A reduced-order model based on the balance between wind load on vegetation and blade restoring forces will be developed and validated by wind tunnel experiments to predict vegetation postures and velocity statistics within the canopy. This understanding will then be applied to determine the aerodynamic loads on aeolian particles, where an advection-dispersion equation will be used to predict vertical profiles of particle mass concentration. Finally, results from the predictive models and laboratory experiments will be further evaluated by field tests at the Oceano Dunes State Vehicular Recreation Area, Pismo Beach, CA using recently developed sand transport instruments for measuring vertical profiles of particle flux for different flexible and rigid vegetation densities. Altogether, this project will deepen fundamental understanding of the mechanisms through which flexible vegetation covers modulate particle entrainment by wind, leading to improved predictive threshold and transport rate models. The research results can also lead to developing more effective control strategies for reducing wind erosion and dust emissions using vegetative covers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

植被在调节风中夹带沉积物中起着重要作用。一旦被夹住的沙子和灰尘颗粒对陆地大气系统中的天气和气候，空气质量，地形和其他组件产生至关重要的影响。在容易受到风侵蚀的地区，整个地球上的庞大地区的植被覆盖物由草和草药组成，茎和叶片具有柔软的茎和叶片。这种类型的植被在足够高的风速下变形，从而改变了风粒相互作用。然而，当前对复杂相互作用的理解仍然有限，并且缺乏解释冠层变形影响的谷物夹带的预测模型。该项目旨在阐明针对柔性檐篷的风田粒子相互作用的潜在物理，并为风化的颗粒夹带开发预测方程。在这项研究中开发和验证的模型将为理解和预测广泛植被覆盖量，风条件和谷物特性的风险夹带打开途径。研究努力的结果将纳入涉及K-12教育，本科研究和研究生研究培训的教育活动中。 包括动手实验和实地考察在内的外展活动将为吸引学生，尤其是在STEM职业生涯中的年轻女性提供独特的机会。该项目的主要目的是结合理论建模，实验室实验和现场测试，以阐明粒子夹带的基础物理，以提高颗粒颗粒颗粒质地的灵活植被罐头，并提高颗粒质地的预测率，并提高了弗洛克斯的预测。根据风隧道实验，将开发和验证基于植被和叶片恢复力之间的风负荷之间的平衡的降级模型，以预测冠层内的植被姿势和速度统计。然后，将应用这种理解来确定风力学颗粒上的空气动力载荷，在该颗粒上，将使用对流分散方程来预测颗粒质量浓度的垂直谱。最后，将使用最近开发的砂转运仪器来测量不同柔性和刚性固定植被密度的粒子通量的垂直曲线，从而通过在加利福尼亚州Pismo Beach的Oceano Dunes州车辆娱乐区进行现场测试进一步评估预测模型和实验室实验的结果。总的来说，该项目将加深对柔性植被覆盖风能调节颗粒夹带的机制的基本理解，从而改善预测阈值和运输速率模型。研究结果还可以导致制定更有效的控制策略，以减少风向侵蚀和尘埃排放。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响审查标准，认为值得通过评估值得支持。