Doctoral Dissertation Research Improvement: Kinetics of Wind-Blown Sand: An Investigation of Unsteadiness in Saltation Systems

博士论文研究改进：风沙动力学：跃迁系统不稳定性的研究

• 批准号: 0425770
• 负责人: Douglas Sherman
• 金额: $ 1.01万
• 依托单位: Texas A&M Research Foundation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0425770&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Improvement; Kinetics

Turbulence is important to sediment transport, whether in air or water. Linkages between turbulent events and pulses in aeolian sediment transport have been difficult to establish, however, especially in non-laboratory environments. One deficiency with field-based studies is that none measured wind velocity and saltation (sediment "jumping," the primary mode of sand transport by wind) with precisely and tightly controlled time and space synchronization. Turbulence has large temporal and spatial gradients, so it seems illogical to expect strong correlations between wind speed and transport rates with instrument separations at meter scale. The goal of this doctoral dissertation research project is to establish and quantify the spatial and temporal scales of unsteadiness in wind and saltation fields; to identify the nature of turbulence causing transport pulsing; to characterize the spatial and temporal dimensions of wind and transport unsteadiness; and to design, build, and deploy a new sensor for the detection of saltating sand grains. Arrays of instruments will be deployed to simultaneously measure the horizontal and vertical dimensions of sediment transport and wind speed. Saltation sensors and anemometers will be placed 2 cm apart to ensure tightly controlled space synchronization. Linkages between turbulent wind events and pulses in sediment transport will be established using variable interval time averaging (VITA), enhanced VITA, and autocorrelation methods. Traps will be deployed to obtain samples of transporting sand to determine their grain size characteristics and moisture content. The research will be conducted in an Australian coastal dune system, but the results will be applicable to sediment transport processes occurring in wind and water at a broad range of settings.This project will provide a fundamental understanding of the response of sand to fluctuating (turbulent) wind conditions. This understanding is a necessary precursor to understanding the deficiencies of wind-blown sediment transport rate models. This research may have implications to coastal managers because they are interested in sediment transport rates. Coastal dunes built by blowing sand also provide a defense against flooding; a characteristic that is especially important in a time where the average global sea level is rising. An increased understanding of aeolian processes and the resultant landforms will improve capabilities to manage or preserve coastal environments. It is essential that fundamental relationships between wind and sand are understood to improve the ability to predict sediment transport rates. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.

无论是在空气还是水中，湍流对于沉积物运输都很重要。 但是，很难在非实验室环境中建立湍流事件与脉冲运输中的脉冲之间的联系。 基于现场的研究的一种缺乏是，没有测量的风速和盐（沉积物“跳跃”，是通过风的主要和紧密控制的时间和空间同步。 湍流具有较大的时间和空间梯度，因此与仪器分离仪表尺度的仪器分离之间的强烈相关性似乎是不合逻辑的。 该博士学位论文研究项目的目的是建立和量化风与盐领域不稳定的空间和时间尺度。确定导致转运脉动的湍流的性质；表征风和运输不稳定的空间和时间维度；并设计，构建和部署一个新的传感器来检测盐砂。 将部署仪器阵列以同时测量沉积物传输和风速的水平和垂直尺寸。 盐传感器和动脉计相距2厘米，以确保紧密控制的空间同步。 将使用可变的间隔时间平均（VITA），增强的Vita和自相关方法建立湍流风事件与脉冲传输中的脉冲之间的联系。 将部署陷阱以获取运输沙子的样品，以确定其晶粒尺寸的特性和水分含量。 这项研究将在澳大利亚沿海沙丘系统中进行，但结果将适用于在广泛的环境中发生在风能和水中的沉积物传输过程。该项目将对沙子对波动（湍流）风条件的响应有基本的了解。 这种理解是理解风吹牛运输速率模型缺陷的必要先驱。 这项研究可能会对沿海经理产生影响，因为他们对沉积物运输率感兴趣。 吹沙子建造的沿海沙丘也为防御洪水提供了防御。在全球海平面上升的时候，一个特征尤为重要。 对风格过程以及由此产生的地貌的越来越多的了解将提高管理或保护沿海环境的能力。 必须将风和沙子之间的基本关系理解为提高预测沉积物传输速率的能力。 作为博士学位论文研究改进奖，该奖项还将提供支持，使有前途的学生能够建立强大的独立研究职业。