The fundamental focus of my research is the problem of fluid flow over complex boundaries. This issue is at the root of many engineering and oceanographic problems ranging from basin scale ocean dynamics to nearshore hydrodynamics and sediment transport modeling to advance marine vessel design.
Environmental Hydrodynamics and Nearshore Processes
My research in environmental hydrodynamics is focused on coastal and estuarine turbulent mixing processes, their interactions with topographic features and the effects of these processes on coastal morphology. I am interested in particular, in the role of flow structure in mass and momentum transport as well as the generation of this structure by topography. Interactions occur via a variety of mechanisms including boundary layer separation and hydraulic flow response. My work presently focuses on dynamics of wave and current flow over rough bathymetry as well as on the generation and evolution of large scale structure in flow around coastal headlands. The influence of these boundary dynamics on sediment transport and on sediment-water column geochemical exchange processes is also of key interest.
Other areas of interest include effects of offshore forcing on nearshore dynamics, the interaction of flow with biological systems, stratified turbulence and laboratory experimental methods.
Projects:
Active:
Coastal Form Drag and Eddies (NSF OCE)
Wave and Current Boundary Layers (ONR)
Permeable Sediment Porewater-Seawater Hydrodynamics (NSF OCE)
Nearshore Water Quality (Sea Grant)
Earlier work:
Field Observations of Tidal Headland Eddies in Deep Water (NSF)
Fluid Dynamics
Active Projects:
Hydrodynamics of Advanced Marine Vessels (ONR)
The ENDEAVOR project is a collaborative effort between the University of Hawaii, Science Applications International Corporation (SAIC) and the Maui High Performance Computing Center (MHPCC), with the aim of developing a design environment for advanced marine vehicles, . We are developing the computational fluid dynamics (CFD) component of the program and carrying out research in support of the overall project goal. Our research focus is on the dynamics of hydrofoils.
Experimental Modeling of Tsunami Effects on Coastal Structures (NSF)
Working with colleagues in the UH Civil Engineering department, we are carrying out experiments at the University of Hawaii and at the Tsunami Wave Basin at Oregon State University to examine the forces of tsunami waves on components of coastal structures. This work is part of collaborative project including researchers at UH, OSU, and Princeton, funded by the NSF Network for Earthquake Engineering Simulation (NEES) program. The primary goals for the work are to establish guidelines for site specific Performance Based Tsunami Engineering (PBTE) for use in risk assessment, loss estimation, and the analysis, evaluation, design and retrofit of coastal structures and facilities.
Transient Jet Dynamics
The initial development of a jet emanating from an orifice involves the rollup of vorticity into a vortex ring which is trailed by a column of high-momentum fluid, subject to shear instabilities. These transient or starting jets play a fundamental role in a range of engineering problems including industrial fluid flows such as fuel and oxidizer jets in combustion chambers, and pressurized vessel breaches. In addition, transient jets are important for environmental flows including tidal exchange at embayments and for biological flows such as blood flow and animal propulsion. Working in collaboration with colleagues at the Universidad Carlos III and at the Universidad de Jaen in Spain, we have carried out laboratory experiments along with numerical modeling exploring the initial development of transient jets, focusing specifically on the role of shear instabilities in determining variations in circulation and strain for the leading vortex ring.