EAR-PF: The Mechanics of Turbulence and Sediment Transport: Physically-Based Numerical Modeling of Flow, Sediment and Bed Evolution in the Bedrock Canyons

劳拉·V·阿尔瓦雷斯博士获得了美国国家科学基金会地球科学博士后奖学金，将在俄克拉荷马大学和西蒙·弗雷泽大学开展一项研究和教育计划。这项拟议的工作将对我们在数值上理解和预测控制河流泥沙输移和河网地貌动力学演变的物理现象作出重大贡献。对宏观湍流事件在沉积物动力学中所起作用的认识将使我们更深入地了解是什么决定了地貌变化，并将导致更有效的模型的发展。该模型还可以用来调查从实验室尺度上进行的良好控制的实验和数值模拟获得的信息在多大程度上可以用来理解更大尺度上的泥沙运动物理，并提供关于河网变化的预测。该研究员将通过开发为期六周的河流建模暑期课程，整合许多拟议的研究实验，进行教育和推广。涡旋解析三维模拟结合现场和实验室观察，可以阐明河流环境中流体动力学和泥沙运动的关键要素。这些模型可以解决与时间相关的、具有重要能量意义的水流湍流结构，捕捉到这些涡旋与可能发生泥沙夹带和沉积的松散床面之间的相互作用。这项研究提出了一个令人信服的战略，将最先进的计算流体力学应用于河流系统中泥沙运动和地貌动力学过程的研究。这项研究的主要目的是利用离散涡模拟技术开发和测试全三维湍流解析模型，该模型可以模拟大范围时空尺度上的湍流及其对泥沙输移、卷吸和淤积以及河道/河段演变的影响。然后，数值模型将用于(1)了解落差流、次生流和流速倒置对河流段泥沙输送、夹带和沉积所起的作用，以及(2)基于河段内宏观湍流效应和速度重新分布的动力学解释地貌动力学变化。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Dr. Laura V. Alvarez has been awarded an NSF Earth Sciences Postdoctoral Fellowship to carry out a research and education plan at the University of Oklahoma and Simon Fraser University. The proposed work will make substantial contributions to our capability to numerically understand and predict the physical phenomena that control sediment transport and morphodynamic evolution of river networks. Gains in the knowledge of the role played by macro-turbulence events in sediment dynamics will allow us to obtain a deeper understanding of what determines the geomorphologic changes and will lead to the development of more efficient models.This model can also serve to investigate to what extent information obtained from well-controlled experiments and numerical simulations conducted at laboratory scale can be used to understand the physics of sediment transport at larger scales and to provide predictions about river network changes. The fellow will engage education and outreach by developing a six-week summer course in fluvial modeling, integrating many of the proposed research experiments.Eddy resolving three-dimensional simulations combined with field and laboratory observations allow elucidation of key elements of fluid dynamics and sediment transport in fluvial environments. These models can resolve the time-dependent, energetically important, turbulent structures of the flow capturing the interactions between these eddies and the loose bed boundaries where sediment entrainment and deposition can occur. This research study proposes a compelling strategy for applying state-of-the-art computational fluid mechanics to the study of sediment transport and morphodynamic processes in fluvial systems. The main objective of the proposed research is the development and testing of a fully three-dimensional turbulence resolving model using Dettached Eddy Simulation techniques that can simulate turbulent flows under a broad range of spatial and temporal scales and their effect on sediment transport, entrainment and deposition and channel/river reach evolution. The numerical model will then be used to (1) understand the role played by the plunging flows, secondary flows and velocity inversions on sediment transport, entrainment and deposition in river reaches and (2) explain morphodynamic changes based on the dynamics of the macro-turbulence effects and velocity redistribution inside the river reach.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.