Transient wave-induced instability in shallow water bottom boundary layers

2004年苏门答腊-安达曼地震和印度洋海啸是人类近代史上最具破坏性的自然灾害之一。灾难发生后，科学家和工程师们一直在共同努力，在印度洋地区建立海啸早期预警系统和海啸减灾计划。要提高我们对海啸的认识，一个有希望的方法是利用海啸产生的沉积物。我们研究的长期目标是将海啸水动力与大陆架和海岸带的泥沙输送过程联系起来。PI们认为，实现这一目标的途径是了解孤立波(或前低压波)下的边界层流动特性。最近对表面波和内波的研究表明，在一定的雷诺数下，流动减速阶段会发生整体不稳定(一种特定类型的空间范围固定的自发性剪切不稳定)，从而导致涡脱落和湍流。本文计划推广Co-PI发展的谱多区域罚函数模型，以进一步研究二维和三维孤立波(和LDN)下的边界层流动。这里概述的研究活动处于几个科学和工程领域--海洋学、流体力学和海岸工程--的交界处，将成为它们之间的桥梁。这项计划中的研究是长期基础研究计划的第一阶段，旨在将海啸水动力学与海啸留下的沉积物相关联。除了以同行评议的文献出版外，还将通过开发和维护一个项目网站来加快项目期间的传播。该项目将培训一名博士生，他将接受数值方法、数据分析和分析求解技术方面的尖端培训。他/她还将接受实验方法方面的扎实培训，以便他/她能够进行模型/数据比较。此外，学生将接受报告写作和口头陈述方面的培训，并将鼓励他/她参加技术会议。

CBET-0756327LiuThe 2004 Sumatra-Andaman earthquake and Indian Ocean tsunami is one of most devastating natural disasters in recent human history. After the disaster, scientists and engineers have been working together to establish an early tsunami warning system and tsunami hazard mitigation programs in the Indian Ocean region. A promising approach for improving our understanding of tsunamis is to use the deposits they create. The long term goal of our research is to relate tsunami hydrodynamics to sediment transport processes on continental shelf and coastal zone. The PIs believe that the path to reach this goal is to understand the boundary layer flow characteristics under solitary (or leading depression) waves. Recent studies on surface and internal waves show that global instabilities (a particular type of spontaneously triggered shear instability of fixed spatial extent) could occur during the flow deceleration phase at certain Reynolds numbers, leading to vortex shedding and turbulence. The PI's plan here to extend the spectral multidomain penalty method model developed by the Co-PI to further investigate the boundary layer flows under solitary (and LDN) waves in both 2D and 3D. The research activities outlined here are at the interface between several field of science and engineering- oceanography, fluid mechanics, and coastal engineering and will serve as a bridge among them. The planned research is the first phase of a long term fundamental research program, which aims at correlating the tsunami hydrodynamics with the sediment deposits left behind by the tsunamis. Dissemination during the project will be expedited by developing and maintaining a project web site, in addition to publishing in the peer-reviewed literature. The project will train one PhD student who will receive cutting-edge training in numerical methods, data analysis and analytical solution techniques. He/she will also have a solid training in experimental methods so that he/she will be capable of performing model/data comparisons. Furthermore, the student will be trained in report writing and oral presentation and he/she will be encouraged to attend technical conferences and meetings.