Interactions between Long Ocean Waves and Muddy Sea Floor

Cornell University, Ithaca NY

Investigators

Abstract

Intellectual Merit: On the continental shelf and in the coastal zone, wind waves interact with sea floor and a number of dynamic processes take place. If the sea floor is composed of sediments, a variety of dissipation mechanisms associated with the sediment rheology play important roles in enhancing wave damping and in modifying wave characteristics. Under this project the investigator will conduct an integrated theoretical and experimental program to accomplish several scientific goals. First, analytical solutions for mud flows under transient wave loadings will be developed to improve our fundamental understanding of various sea bottom dissipative mechanisms and their impacts on transient long wave propagation. Second, An archive of quality detailed experimental data sets that researchers may use to test their own analytic and numerical models will be generated. Third, model-data comparisons will be performed to understand the limitations of analytical solutions and direct numerical simulation (DNS) models for mud flows under wave loadings will be developed to further explore the physical processes. A Navier-Stokes solver with different stress-strain relationships, which depend on the rheology of the fluid mud, will be developed for various wave loadings. Fourth, depth-integrated, phase-resolving wave propagation models with sea bottom dissipative mechanisms included will be developed. A case study is planned to examine the wave attenuation in the Guyana coastal system that is characterized by very thick deposits of Amazon mud. Broader Impacts: The proposed research activities are at the interface between several field of science and engineering ¨C oceanography, fluid mechanics, and coastal engineering and will serve a bridge among them. The project will train one PhD student who will receive cutting edge training in experimental techniques, numerical methods and analytical solution techniques. Furthermore, the student will be trained in report writing and oral presentation and he/she will be encouraged to attend technical conferences and meetings. The DNS numerical models to be developed in the proposed project will be useful as research tools for many related engineering science field and can be employed after some modifications to investigate wave©\induced soil failures, debris flows and scouring around coastal structures. The Boussinesq-type wave models with the seafloor dissipative mechanisms considered, which are the main products of the project, will be useful tools for coastal engineers in various applications in the coastal regions where muddy seabeds are present. The new Boussinesq-type model can also be used to investigate the sediment transport and deposit during tsunamis. The laboratory data will be used to benchmark other numerical models under current and other development. To expedite the dissemination of what is learned during the project, we will develop and maintain a project web site, in addition to publishing manuscripts in the peer-reviewed literatures. Most of the investigator¡¯s research activities can be found on the following webpage: http://ceeserver.cee.cornell.edu/pll-group/index.htm Several upper-level undergraduate and graduate student courses at Cornell will be benefit significantly from the research project, as the laboratory measurement techniques developed in the project can be used in these courses. Currently the investigator is supervising 3 REU students supported by NSF and Engineering College fund. In the proposed project, he will carry on this tradition and encourage interested undergraduates to participate in research.