Meandering Morphodynamics and Related Fluvial Processes

这项研究计划旨在促进对笔直和曲折河流中水流和泥沙输送过程的理解和分析处理，从而改进发生在这些河流中的关键大规模过程的数学模型。 未来五年，将围绕两个主题开展研究：曲折河流平面演变的动力学和模拟(主题A)和大尺度湍流(主题B)。主题A下的研究侧重于克服与曲流流的模拟及其与河流活动边界的相互作用有关的悬而未决的问题。在主题B下，将扩大关于大尺度湍流的知识，以包括对大尺度水平相干结构的动力学和形态后果的初步了解。具体目标如下：(1)发展一个有效的二维水动力模型来计算曲流流，包括适当的三维效应的参数化；(2)发展新的岸坡侵蚀解析公式；(3)发展一个计算曲流河长期平面演变的数值模式，并用它来检验、改进和验证目标1和目标2所开展的研究所得到的水流和岸坡侵蚀的新公式；以及(4)穿透在直或近直的河流中出现的大尺度湍流水平相干结构的生命周期的动力学，并洞察其形态后果。 出于目前的目的，将在大型设施中进行广泛的一系列实验室实验，包括用于曲折研究的两个不同的1米宽、50厘米深的由三个连续的曲流环形成的河道，以及用于湍流研究的长21米、宽度可调1至2米的直槽。最先进的设备将被用来获得河床和平面形状形态调整的详细记录，并测量瞬时和时间平均水流速度场，以及局部泥沙输移率。将收集文献中的实地数据和与水有关的机构提供的未发表数据，以进一步了解正在调查的过程，并能够进一步测试这项研究产生的计算机模型。 拟议研究产生的新知识和工具将直接适用于一系列广泛的河流工程研究和项目的可行性分析、设计和优化，以及制定健全的河流管理准则和协议。这项研究将培养5名博士、2名硕士和3名理科学生，他们将获得高度期望的水力物理和数值模拟方面的高级技能，以及对河流工程和管理的社会、经济和环境方面的深刻理解。

This research program aims at advancing the understanding and analytical treatment of flow and sediment transport processes in straight and meandering rivers, leading to an improved mathematical modelling of key large-scale processes taking place in such rivers. Over the next five years, the research will be carried out along two themes: the dynamics and modeling of the planimetric evolution of meandering streams (Theme A) and large-scale turbulence (Theme B). The research under Theme A focuses on overcoming unresolved issues related to the modeling of meandering flow and its interaction with the stream movable boundary. Under Theme B, the knowledge on large-scale turbulence will be extended to include a first understanding of the dynamics and morphological consequences of large-scale horizontal coherent structures. The specific objectives are as follows: (1) to develop an efficient 2-D hydrodynamic model for the computation of meandering flow, including appropriate parametrizations of three-dimensional effects; (2) to develop new analytical formulations of bank erosion; (3) to develop a numerical model for the computation of long-term planimetric evolution of meandering streams, and use it to test, refine and validate the new formulations of flow and bank erosion resulting from research carried out under objectives 1 and 2; and (4) to penetrate the dynamics of the life-cycle of large-scale turbulence horizontal coherent structures occurring in straight or nearly straight streams, and gain insight into their morphological consequences. For the present purposes, extensive series of laboratory experiments will be conducted in large-scale facilities, including two different 1 m wide, 50 cm deep channels formed by three consecutive meander loops for the meandering studies, and a 21m-long straight flume with adjustable width from 1 to 2m for the turbulence studies. State-of-the-art equipment will be used to obtain detailed records of bed and plan shape morphological adjustments, and measure instantaneous and time-averaged flow velocity fields, and local sediment transport rates. Field data from the literature and unpublished data available from water-related agencies will be gathered, to get further insights into the processes under investigation and enable further testing of the computer models resulting from this research. The new knowledge and tools resulting from the proposed research will be directly applicable to the feasibility analysis, design and optimization of an extensive array of river engineering studies and projects and the development of sound river management guidelines and protocols. The research will result in the training of 5 PhD, 2 MSc and 3 BSc students, who will acquire highly desired, advanced skills in hydraulic physical and numerical modeling, and a deep appreciation of the social, economic and environmental aspects of river engineering and management.