Career: Advanced Numerical Modeling of Bridge Foundation Scour

这一职业奖项的提议是出于对解决桥墩和桥台冲刷问题的综合研究战略的需要，桥墩和桥台冲刷是桥梁故障的主要原因，在最近的严重洪灾中，桥梁故障摧毁了国家的交通基础设施。由于这一问题的巨大复杂性，为了使这种策略有效，它必须将现场和实验室实验与三维计算建模相结合。这项工作的目的是开发一个先进的计算流体力学模型，通过结合复杂的三维水流的数值和湍流模拟的最新进展，以及一种新的方法来模拟导致冲刷的泥沙输送过程。数值方法将依赖于用先进的湍流模型封闭的非定常三维雷诺平均Navier-Stokes(RANS)方程，它解决了近壁流动，考虑了湍流的各向异性，并可以模拟床面粗糙度。这种水平的湍流模拟对于再现驱动冲刷过程的地基诱导的大尺度漩涡的结构和强度至关重要。将发展拉格朗日/欧拉耦合方法来模拟泥沙颗粒的输运和模拟冲刷的时间发展。以多重网格加速和预处理策略为特征的高效数值方法将被用来求解与时间相关的控制方程。现有实验室实验的数据将用于校准和验证数值模型。这项研究将产生一个先进的计算框架，可以用来加强我们对导致野外冲刷的复杂机制的理解，而这一详细程度以前仅通过野外和实验室实验是无法获得的。该数值模型与试验研究相结合，将有助于评估桥梁设计的冲刷敏感性，并在深入了解水流物理的基础上制定冲刷对策。因此，这项工作可能会对目前的技术水平产生重大影响，目前的技术水平几乎完全依赖于从小规模实验室测量得出的经验相关性。此外，数值模型将通过澄清诸如将小规模试验结果缩放到全尺寸条件的效果以及冲刷向平衡的时间发展等问题来帮助指导未来改进的试验。这一职业计划的教育贡献将包括：i)为土木和环境工程师提供计算流体力学和水力学领域的新课程；ii)直接让本科生参与研究的项目；以及iii)关于不可压缩湍流数值模拟的研究生水平教科书。

Abstract9875691The proposal for this CAREER award was motivated by the need for a comprehensive research strategy to address the problem of bridge pier and abutment scour, the leading cause of bridge failures that devastated the nation's transportation infrastructure during recent severe floods. Due to the enormous complexity of this problem, for such a strategy to be effective it must integrate field and laboratory experiments with three-dimensional computational modeling. It is the objective of this work to develop an advanced computational fluid dynamics model by combining the latest advancements in numerical and turbulence modeling of complex, three-dimensional flows with a novel approach for modeling the sediment transport processes that lead to scour. The numerical methodology will rely on the unsteady, three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations closed with advanced turbulence models, which resolve the near-wall flow, account for turbulence anisotropy, and can simulate bed roughness. Such level of turbulence modeling is essential for reproducing the structure and intensity of the foundation-induced, large-scale vortices that drive the scouring process. A coupled Lagrangian/Eulerian approach will be developed for modeling the transport of sediment particles and simulating the temporal development of scour. Efficient numerical methods, featuring multigrid acceleration and preconditioning strategies, will be used to solve the time-dependent governing equations. Data from existing laboratory experiments will be used to calibrate and validate the numerical model. This research will lead to an advanced computational framework that can be used to enhance our understanding of the complex mechanisms that induce scour in the field at a level of detail not previously accessible by field and laboratory experiments alone. The numerical model, employed in conjunction with experimental studies, will facilitate the evaluation of bridge designs for scour susceptibility and the development of scour countermeasures that are based on in-depth understanding of the flow physics. Therefore, this work could potentially have a significant impact on the current state-of-the-art, which relies almost exclusively on empirical correlations derived from small-scale laboratory measurements. Furthermore, the numerical model will help guide future improved experiments by clarifying issues such as the effect of scaling the results of small-scale experiments to full-scale conditions, and the time development of scour toward equilibrium. The educational contributions of this CAREER plan will include, among others, the following: i) a new curriculum for Civil and Environmental engineers in the area of computational fluid dynamics and hydraulics; ii) projects for directly involving undergraduates in research; and iii) a graduate-level textbook on the numerical simulation of incompressible turbulent flows.