Sonic Characterisation of Water Surface Waves, Turbulence, Mixing and Bed Friction in Shallow Water Flows

在许多情况下，包括砾石床河流、陆上水流和部分充满的管道中的水流都是湍动的。这种深度受限的流动在空气/水边界上总是有小波的图案。我们认为，这些小波的动力学行为携带了关于该流动中的湍流混合和能量损失的信息。在工程计算中，通常假定水面是平坦的，因此忽略了这一潜在的非常有价值的信息来源。该项目将使用实验室观测和复杂的3D数值模型来研究和预测湍流在粗糙的固体边界上产生的湍流结构。这些流动结构然后上升到水面，使其振荡，并创造出独特的小浪模式。该数值模式将能够在三维中预测这些流动结构的产生、发展和输送，并捕捉到它们对水面格局的影响。人们相信，通过测量波型，就有可能预测流动中的混合和能量损失。该数值模型将被用来模拟各种物理尺度、河床粗糙度类型和水流深宽比的情况，以便研究非常广泛的流态。水面上的波型可以用多种方法测量，例如光学、电磁和声学方法。声学测量特别适合于液压应用，因为它们快速、低成本、非侵入性，并且可以很容易地在小范围和大范围内使用。可以将声能投射到移动的水面图案上的机载声学传感器将被放置在水道或管道的水面上方。通过检查声反射，将测量空气-水边界的行为。需要新的声信号分析方法和声传播理论，才能从测量到的声反射重建出水面的细微细节。然后，处理后的声学数据将与从实验室和3D数值研究中获得的知识相结合，为工程师提供仅通过测量空气-水边界来估计能量损失和湍流混合的关系。需要有关能量损失和湍流混合的信息来预测洪水研究的水位，并预测意外释放到河流和管道中的污染物和沉积物的混合情况。该系统将能够提高洪水预报和预警，从而更好地保护人民和他们的财产。更好地评估水体中的湍流混合将有助于更好地保护自然环境和敏感生境。在该项目的最后部分，将在环境局的一个测试设施中，在塔夫河制造和全面测试传感器系统的原型。结果将被用来证明这一概念和技术对最终用户的实际适用性。

Flows found in many situations including gravel bed rivers, overland flows, and in partially filled pipes are turbulent. Such depth-limited flows always have patterns of small waves on the air/water boundary. We believe that the dynamic behaviour of these small waves carries information about the turbulent mixing and energy losses within that flow. Normally in engineering calculations the water surface is assumed to be flat and so this source of potentially very valuable information is ignored. This project will use laboratory observations and a complex 3D numerical model to study and predict the turbulent flow structures that are created by turbulent flows over rough solid boundaries. These flow structures then rise to the water surface and cause it to oscillate and create a distinct pattern of small waves. The numerical model will be able to predict the generation, growth and transport of these flow structures in 3D, and capture their effect on the water surface pattern. It is believed that by measuring the wave pattern it will be possible to predict the mixing and energy losses within the flow. The numerical model will be used to simulate this process for a wide range of physical scales, bed roughness types and flow depth to width ratios, so that a very wide range of flow regimes will have been examined.The wave pattern on a water surface can be measured using a number of methods; e.g. optical, eletromagnetic and acoustic. Acoustic measurements are particularly suited to hydraulic applications because they are fast, low-cost, non-invasive, and can be easily used at both small and large scales. An airborne acoustic sensor that can project sound energy onto the moving water surface pattern will be placed above the water surface in a channel or pipe. By examining the acoustic reflections, the behaviour of the air-water boundary will be measured. New methods of acoustic signal analysis and sound propagation theory are needed to re-construct the fine detail of the water surface patterns from the measured acoustic reflections. The processed acoustic data will then be combined with the knowledge gained from the laboratory and 3D numerical studies to provide engineers with relationships to estimate energy losses and turbulent mixing solely from measurements of the air-water boundary. Information on energy losses and turbulent mixing is needed to predict water levels for flood studies and to predict the mixing of pollutants and sediments accidentally released into rivers and pipes. This system will be able to improve flood prediction and warning, so providing better protection for people and their property. Better assessment of turbulent mixing in water bodies will help to protect better the natural environment and sensitive habitats. In the final part of the project, a prototype sensor system will be manufactured and tested at full scale in the River Taff, at an Environment Agency test facility. The results will be used to demonstrate the practical applicability of the concept and the technology to end users.