CENTER FOR COMPUTATION & TECHNOLOGY

Many naval operations occur in littoral regions between a moving shoreline and water depths of 10~20 meters, including river mouths and estuaries. The success of such operations depends on the in-depth understanding and accurate prediction of the physical environment in these highly nonlinear and dynamic regions. In nature, sediments covering the world's coastal ocean bottoms are rather diverse, ranging from permeable sands to silts and clays. The Louisiana coast with sandy barrier islands, tidal flats and soft mud bottoms is losing 25 to 30 square miles of coastal wetlands each year. Protection and restoration of the Louisiana coast requires better predictive capabilities of coastal processes in the deltaic sedimentary environment It is well known that many physical processes, such as undertows, rip currents and longshore currents as well as morphological responses, are controlled by the transformation and breaking of surface waves on the open coast, while river discharges and tide/wind-driven circulation are the primary forcing agents for morphological changes in river mouths and estuaries. An accurate prediction of nearshore surface waves, coastal circulation and sediment transport is essential to many military and civilian operations in coastal regions.

Although the second-generation Boussinesq-type models have proven to be effective tools to simulate nearshore wave propagation and breaking-generated horizontal circulation, applications are still limited by high computational costs as well as the assumptions of idealized seabed conditions and weak horizontal vorticity components, which may not be applicable in deltaic or river mouth environments with soft mud seabed and strong stratification owing to large fresh water inflows. It is well known that the accuracy of nearshore sediment transport models strongly depends on the accuracy of the driving force, or the result of the hydrodynamic modelThe need for advanced wave and hydrodynamic modeling tools and a better understanding of the coastal processes in deltaic sedimentary and hydrodynamic environments calls for a new generation of Boussinesq-type models with much higher accuracy in dispersion, nonlinearity and vorticity as well as new numerical solution and computing techniques.

Simulation data may be analyzed and visualized by a range of external applications, such as Amira, IDL, or OpenDX, and can also be analyzed in-line by use of a web-server module. Cactus is used and developed by numerous application communities internationally, including Numerical Relativity, Climate Modelling, Astrophysics, Biological Computing, and Chemical Engineering. It is a driving framework for a number of computing infrastructure projects, particularly in Grid Computing, such as GridLab, GriKSL, and the Astrophysical Simulation Collaboratory.
The long-term goal of the proposed study is to develop and enhance the research and educational capabilities in the area of coastal engineering and science in the Department of Civil and Environmental Engineering (CEE) at Louisiana State University (LSU) while simultaneously supporting the Navy's research goals in the areas of Coastal Geosciences (Code 321) and Physical Oceanography (Code 322).

The specific objectives of this project are to:

• develop the capability of modeling coastal circulation and nearshore surface waves in deltaic sedimentary and hydrodynamic environments in an integrated modeling framework by extending the Boussinesq theory for nearshore hydrodynamics to muddy coasts and non-hydrostatic three- dimensional (3D) flow regimes with stratifications,
• complement the Office of Naval Research recent research initiatives on Tidal Flats and Wave-Mud Interactions by integrating the new modeling system with the field data collected in those programs.
• simulate large-scale, long-term problems in the deltaic environment by integrating the application-oriented modeling system with massive-processor computing facilities and technologies available at LSU and in Louisiana.

Publications/References

• T. Goodale, G. Allen, G. Lanfermann, J. Massó, T. Radke, E. Seidel, J. Shalf, The Cactus Framework and Toolkit: Design and Applications, Vector and Parallel Processing -- VECPAR 2002, 5th International Conference, Lecture Notes in Computer Science, Springer, Berlin, 2003.
• Chen, Q., Madsen, P. A., Schaffer, H. A., and Basco, D. R. (1998). Wave-current interaction based on an enhanced Boussinesq approach. Coastal Engineering, 33, 11-39.
• Chen, Q., Dalrymple, R. A., Kirby, K. T., Kennedy, A. B., and Haller, M. C. (1999a). Boussinesq modeling of a rip current system. Journal of Geophysical Res., 104 (C9), 20,617-20,637.
• Chen, Q., Madsen, P. A. and Basco, D. R. (1999b). Current effects on nonlinear interactions of shallow-water waves. Journal of Waterway, Port, Coastal and Ocean Engineering, 125(4): 176-186
• Chen, Q., Kirby, J. T., Dalrymple, R. A., Kennedy, A. B. and Chawla, A., (2000). Boussinesq modeling of wave transdormation, breaking and runup. II: 2D. J. of Waterway, Port, Coastal and Ocean Eng., 126: 48-56.
• Chen Q., Kirby, K. T., Dalrymple, R. A., Shi, F. and Thornton, E. B. (2003). Boussinesq modeling of longshore currents. Journal of Geophysical Res. Vol. 108, No. C11, 3362-3380.
• Chen, Q., Kaihatu, J. M., and Hwang, P. A. (2004). Incorporation of the wind effects into Boussinesq wave models. Journal of Waterway, Port, Coastal and Ocean Engineering, 130 (6): 312-321.
• Chen, Q., Zhao, H., Hu, K, and Douglass, S. L (2005). Prediction of wind waves in a shallow estuary. Journal of Waterway, Port, Coastal and Ocean Engineering, 131 (4): 137-148.
• Chen, Q. (2006). Fully nonlinear Boussinesq-type equations for waves and currents over porous beds. J. of Eng. Mechanics. 132 (2): 220-230.
• Cruz, E. and Chen, Q. (2006). Fundamental properties of Boussinesq-type equations for waves and currents over a permeable bed. Coastal Engineering Journal. 48 (3): 225-256.
• Cruz, E. and Chen, Q. (2007). Numerical modeling of nonlinear waves on heterogeneous porous beds. Ocean Engineering. 34: 2303-1321..
• Cruz, E. and Chen, Q. (2007). Numerical modeling of nonlinear waves on heterogeneous porous beds. Ocean Engineering. 34: 2303-1321.
• Chen, Q., Wang, L., Zhao, H., and Douglass, S. L. (2007). Predictions of storm surges and wind waves on coastal roadways. Journal of Coastal Research. In press.
• Chen, Q., and Wang, L. (2007). Topographic and dynamic control of storm surge: Hurricane Katrina. Submitted..

Participants

Senior Staff

• Dr. Q. Jim Chen (CEE/CCT)
• Dr. Gabrielle Allen (CCT/CS)
• Dr. Mayank Tyagi (CCT)
• Dr. Claes Eskilsson (CEE/CCT)

Students

• Razvan Carbunescu (undergrad/CS)
• Qin Fan (graduate)

Links

• http://www.cct.lsu.edu/eng/ceeweb.nsf/index
• http://www.onr.navy.mil/sci_tech/32/321/coastal_geosciences.asp
• http://chinacat.coastal.udel.edu/~kirby/programs/nearcom/

Contact
For more information about the coastal modeling project at CEE/CCT please contact Dr. Q. Jim Chen, Department of Civil & Environmental Engineering (CEE), 3418 CEBA, Louisiana State University, Baton Rouge, LA 70803, Phone: (225)578-4911; Fax: (225)578-8652; E-mail: qchen@lsu.edu

Acknowledgements
Coastal modeling project is funded through DoD-EPSCOR (grant# ).