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.

植被在调节风对泥沙的夹带方面起着重要的作用。一旦夹带沙尘颗粒，对天气和气候、空气质量、地形和陆-气系统中的其他组成部分产生至关重要的影响。地球上广大地区的植被覆盖着易受风力侵蚀的地区，这些地区的植被由茎和叶片柔韧的草和草本植物组成。这种类型的植被在极高的风速下变形，从而改变了风与粒子的相互作用。然而，目前对复杂相互作用的理解仍然有限，并且缺乏考虑冠层变形影响的谷物夹带预测模型。本计画的目的在于阐明弹性林冠风-植生-粒子交互作用的基本物理机制，并发展风成颗粒夹带的预测方程式。在这项研究中开发和验证的模型将开辟一条途径，了解和预测风夹带在广泛的植被覆盖量，风的条件，和粮食属性。从研究工作的结果将被整合到涉及K-12教育，本科研究和研究生研究培训的教育活动。 该项目的主要目标是将联合收割机理论建模、实验室实验和实地测试结合起来，阐明柔性植被冠层颗粒夹带的基本物理学原理，这将有助于改善颗粒夹带阈值的预测，浓度和通量率。一个降阶模型的基础上的植被和叶片恢复力的风载荷之间的平衡，将开发和验证风洞实验，以预测植被的姿态和速度统计冠层内。然后将这种理解应用于确定风成颗粒上的空气动力学载荷，其中对流-弥散方程将用于预测颗粒质量浓度的垂直分布。最后，预测模型和实验室实验的结果将进一步评估的现场测试在奥恰诺沙丘国家车辆娱乐区，皮斯莫海滩，CA使用最近开发的沙传输仪器测量不同的灵活和刚性植被密度的颗粒通量的垂直剖面。总之，该项目将加深对灵活的植被覆盖调节风夹带颗粒的机制的基本理解，从而改进预测阈值和传输速率模型。该研究成果也可以导致开发更有效的控制策略，减少风蚀和粉尘排放使用vegetative covers.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。