September 2011

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Link Fellowship Awardees For 2011

Ocean Engineering and Instrumentation

 

After graduating from the National Organization for Developing Exceptional Talents High School in the country of art and culture, Iran, Masoud was accepted to Sharif University of Technology, the most prestigious engineering university in the country.  Upon finishing his B.Sc. degree in Mechanical Engineering, Masoud decided to go through a different journey by picking one of the most disciplined countries on the planet as his next stop, Sweden.  He earned his M.Sc. degree in the field of Naval Architecture and Ocean Engineering from Chalmers University of Technology in Gothenburg.  Hawaii was his next stop where he joined the Department of Ocean and Resources Engineering at the University of Hawaii at Manoa and is currently pursuing a Ph.D. degree under the supervision of Professor R.C. Ertekin.

Link Foundation Research Project: Water Wave Impact on Decks of Coastal Structures
Advisor: Professor R. Cengiz Ertekin

Coastal structures are subjected to severe wave-induced loads under extreme conditions such as hurricanes or storms. Storm surge brings the water level to higher elevations and closer to the deck of coastal structures. The increase in water level allows for larger set of waves to approach the structure, waves that would otherwise break farther offshore. The wave, accompanied by the storm surge, can impinge on the deck and induce a load that exceeds the resistance of the structure. Complete or partial failure of the coastal bridges during hurricanes Ivan (2004) and Katrina (2005), for instance, due to the storm wave-induced loads, not only caused significant financial loss but it also created a dramatic delay in delivering emergency needs to the victims of such destructive events.

In this project, the storm and tsunami wave-induced loads on the coastal structures will be modeled by the Green-Naghdi (G-N) theory of water waves. The G-N theory is a nonlinear, dispersive, shallow water wave theory based on the theory of Directed Fluid Sheets. In the original form of the equations, incompressibility is the only assumption made for the continuum. Conservation laws of mass, linear momentum and director momentum are postulated by the G-N equations. The nonlinear, time- and space-dependent partial differential G-N equations satisfy the free-surface and body boundary conditions exactly. The equations, also, allow for time- and space-dependent changes in seafloor, enabling the theory to model complex phenomenon such as creation of tsunami waves.

First, propagation of the three-dimensional waves in shallow waters will be modeled using the G-N theory. Then, the two-dimensional interaction of the shallow water waves with the decks of coastal structures, with or without the storm surge, will be discussed using the two-dimensional version of the G-N equations. As a result, pressure distribution around the structure, and therefore the wave-induced loads, can be determined. Formation of entrapped air pockets beneath the deck of the structure will be studied by coupling the adiabatic gas relation and the G-N equations and seeking the solution through an iterative approach. Finally, an interface capturing method, namely Volume of Fluid method, will be coupled with the Euler equations inside the domain to model the extreme cases of wave breaking and overtopping on top of the deck.

Once the formulation of the problem is completed, wave-induced loads on the structure will be calculated by solving the equations analytically or numerically. The results will be validated with the existing laboratory experiments. At last, the model will be used to assess the vulnerability of prototype structures during a storm, hurricane or tsunami event.

 

Heather Beem attended Oklahoma State University for her Bachelor’s in Mechanical Engineering. Despite having grown up in a land-locked state, childhood expeditions of tromping through streams with her aquatic biologist father grew into her desire to explore the oceans. She was thus drawn to the MIT/WHOI Joint Program, where she is both immersed in cutting edge engineering and works with leaders in developing ocean technologies. She is now embarking on the PhD portion of her graduate studies, and is excited to dive in!

Heather’s research interests are fueled by a fascination with animals’ innate skills that serve them in the marine environment. Their quick maneuvers and clever sensing mechanisms have been refined over many years and should serve as inspiration for next-generation underwater vehicles. The underlying physics of these items are largely governed by fluid mechanics, and as such is the focus of Heather’s research.

Link Foundation Research Project:  Seal Whisker Inspired Flow Sensor
Advisor:  Michael Triantafyllou

Studies show that harbor seals are adept at tracking small movements in the water, such as those left in the wake of fish, by using their highly sensitive whiskers to detect fluid structures, even without auditory or visual cues. Moreover, it has been claimed that the unique morphology of the harbor seal whisker suppresses Vortex Induced Vibrations (VIV). This implies that the geometry is specialized to reduce the background noise caused by the whisker’s own wake in the detection of the upstream target. 
This project will utilize experimental fluids mechanics to investigate this intriguing claim, and develop a flow sensor that mimics the seal’s wake sensing capabilities.

 

Elizabeth attended the University of California, Santa Barbara, for her Bachelor’s degree in Aquatic Biology. During her undergraduate studies, she joined an intertidal ecology lab which provided her the opportunity to dive into field research. While her studies and research primarily focused on biology and ecology, she took a breadth of interdisciplinary ocean science courses. This interdisciplinary exposure shaped her research interests in biophysical coupling between ambient flow regimes and organism behaviors to determine the influence on population distributions.

Elizabeth is now working on her doctoral research at the UW, School of Oceanography. She is interested in the population dynamics of harmful bloom-forming algae that have both benthic and pelagic life stages. Her research focuses on the role of individual cell motility “behavior” in algal bloom formation and termination. She utilizes video-based methods to characterize algal cell movements and distributions. The ultimate goal of her research is to better inform geophysical models used for harmful algal bloom forecasts.

Elizabeth is also very interested and dedicated to science education and outreach. During her Master’s program at the UW, School of Oceanography, she taught in a high school marine science classroom for two years as an OACIS GK-12 fellow.   

Link Foundation Research Project:  Novel optical remote sensing technology for prediction of Harmful Algal Blooms
Advisor:  Daniel Grünbaum 

Harmful algal blooms (HABs) are outbreaks of toxic or noxious planktonic algae that can threaten public health, degrade aquatic ecosystems and cause significant economic losses. HABs already affect nearly every coastal environment and are increasing worldwide in frequency and severity.  Most harmful algae are detected only after they have reached large planktonic populations, when they have already caused ecological or economic damage. Most HAB-forming species have two distinct life stages, a dormant benthic stage and a vegetative pelagic stage. Algal cells emerging from the benthic stage regulate the timing, location and magnitude of the HABs. Emerging cells provide a promising but currently unexplored strategy for the early detection and prediction of HABs.

This project is to construct and deploy a remotely-operable optical sensor that uses established video-based tracking techniques to detect and characterize behaviors of HAB-forming algae as they emerge from the sediments.