Direct numerical simulation of shallow flows over a rough bottom boundary: On the interaction between the deformable free-surface and the roughness-generated turbulence

粗糙底部边界上浅流的直接数值模拟：可变形自由表面与粗糙度产生的湍流之间的相互作用

• 批准号: 402125106
• 负责人: Dr.-Ing. Aman Ghebremichael Kidanemariam
• 金额: --
• 依托单位: Department of Mechanical Engineering
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/402125106?language=en
• 关键词: Direct; numerical; simulation; shallow; flows

Free-surface shallow flows are ubiquitous in nature. They are found in lowland alluvial rivers, estuaries, coastal areas and in man-made canals. The air-water interface in such flows is commonly observed to undergo a continuous spatio-temporal evolution featuring waves at a wide range of scales. Fundamental understanding of the mechanisms behind the free-surface dynamics is crucial from an environmental and engineering point of view as it greatly influences a number of relevant processes such as sediment and solute transport, interfacial mass and heat transfer and pollution dispersion. The rich dynamics of the free-surface is a consequence of a complex interplay between stabilizing and destabilizing factors such as gravity, the chaotic turbulent motion of the flow beneath and the evolving sediment bed. The proposed project aims to numerically investigate the physical mechanisms behind the often observed free-surface phenomena in turbulent shallow flows. To this end, a dedicated tool which utilizes state-of-the-art computational resources to simulate large-scale free-surface flows will be developed. Subsequently, the tool will be deployed to generate high-fidelity numerical data which resolves all the relevant scales of the problem. Rigorous analysis of the generated data will then follow to address the aforementioned coupled-interaction among the free-surface, the turbulent flow and the bottom rough bed. The results obtained in this project will fill existing knowledge gaps concerning the free-surface dynamics in environmentally-relevant shallow flows. It is anticipated that the results will serve as an important input in improving predictive models of the intrinsic processes in such flow configuration.

自由表面浅层流动在自然界中无处不在。它们存在于低地冲积河流、河口、沿海地区和人工运河中。这种流动中的空气-水界面通常被观察到经历了一个连续的时空演变，其特征是大范围尺度上的波动。从环境和工程的角度来看，从根本上理解自由表面动力学背后的机制是至关重要的，因为它极大地影响着一些相关的过程，如沉积物和溶质的迁移、界面质量和热的传递以及污染的扩散。自由表面丰富的动力学是稳定和不稳定因素之间复杂相互作用的结果，如重力、下方水流的混乱湍流运动和不断演变的沉积物床。该项目旨在数值研究在湍流浅流中经常观察到的自由面现象背后的物理机制。为此，将开发一种专用工具，利用最先进的计算资源来模拟大规模自由表面流动。随后，将部署该工具以生成高保真的数字数据，以解决所有相关尺度的问题。随后将对生成的数据进行严格的分析，以解决上述自由面、湍流和底部粗糙床之间的耦合作用。该项目所取得的成果将填补有关与环境有关的浅水水流中自由表面动力学的现有知识空白。预计结果将作为改进这种流动结构中内在过程的预测模型的重要输入。