Transient wave-induced instability in shallow water bottom boundary layers

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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.