CROSSTEX - Swash Zone Hydrodynamics and Sediment Transport

Cornell University, Ithaca NY

Investigators

Abstract

0452862 This proposal is a part of the Cross Shore Sediment Transport Experiments (CROSSTEX), designed as a multi-investigator project that is focused on cross-shore sediment transport processes in the coastal zone. CROSSTEX consists of three sub-group projects that address different coastal sediment transport processes, including sheet flow transport in the swash zone, suspended transport in the inner and outer surf zone and short-term morphological changes. These projects are interconnected by the nature of the problems to be studied and by the conducting of an integrated and shared experiment in the large wave flume at the Oregon State University (OSU). This project specifically seeks a better understanding of small-scale sediment transport processes in the swash zone. The instantaneous fields of concentration and fluid and sediment particle velocity will be measured in the sheet flow layer and these measurements and the directly calculated turbulent statistics, including the particle stress, will be used to test existing two-phase sediment transport models and to guide their further development. To achieve the objectives, an integrated experimental, theoretical and computational research program is proposed. Dr. Philip Liu will lead a research team to develop simulation models based on the two-phase Reynolds Averaged Navier-Stokes (RANS) equations. In collaboration with other research groups in the CROSSTEX, a series of near prototype scale experiments will be conducted in the large wave flume at the OSU. A new Fiberscope Measurement System (FMS) will be designed with a remotely controlled positioning device. By adopting quantitative imaging techniques, such as particle imaging velocimetry (PIV), simultaneous high-resolution measurements of both fluid and sediment particle velocities can be obtained. Dr. Edwin Cowen will be responsible for the design and performance of the FMS. Broader Impacts: The research is at the interface between several fields of science and engineering- fluid dynamics, oceanography, geology, soil mechanics, and applied mathematics- and will serve as a bridge among them. All graduate students involved in the project will receive cutting-edge training in mathematical modeling, numerical methods, and experimental techniques. The numerical models to be developed will be useful as research tools for many related engineering science fields and can be employed to investigate wave-induced soil failures, scouring around coastal structures, debris flows, and sand dune migration. The laboratory data will be used to benchmark other numerical models under current or future development. A project web site will be developed to disseminate the results broadly in addition to publishing manuscripts in the peer-reviewed literature. The research program will have significant impacts on our academic programs. Several upper-level undergraduate and graduate student courses at Cornell will benefit significantly from the research program, as the instruments developed in this project will be used in these courses and the experimental and numerical results will be included in the course material. We will also make every effort to directly expose undergraduate students to the research. Oregon State University is currently an REU site. At Cornell, the PIs and REU participants will work with staff members of the Sciencenter on exhibits on both the mechanics of sediment deposition and scour in rivers and along coasts. At Oregon State University, the PIs also have good working relationships with the local aquarium and science museum and will distribute distilled versions of CROSSTEX to them. Finally, the processes leading to sediment transport in the swash and the methodology developed in this study are relevant to sediment transport caused by tsunamis.