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Posted 7/26/2013

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Engineer Research and Development Center

HANOVER, N.H.—As a continuing research project, New York University (NYU) scientists and students were recently at ERDC’s Cold Regions Research and Engineering Laboratory (CRREL) conducting research in the laboratory’s flume for follow-on testing of sea ice scallops, a fundamental approach to better understand the dynamics of melting glaciers and climate change.

“There are two reasons that we are studying sea ice scallops,” said Professor Dave Holland, with NYU’s Center for Atmospheric and Ocean Science.  “The first being that we are curious, so this is curiosity-driven science, and the other reason is that we are looking at the melting of sea ice in an ocean planet to get a better understanding of how climate change is impacting the melting.”

CRREL partners with a wide variety of researchers to better understand the basic fundamentals of science, while using the laboratory’s unique facilities and leveraging CRREL’s expertise.

Using CRREL’s flume, a 120-ft-long by 4-ft-wide and 2-ft-deep freshwater channel, scientists can study processes, such as those NYU recently conducted, in a controlled environment.  The flume’s bed is refrigerated, which allows the scientists to grow an ice sheet on the bottom of the channel while allowing an active water flow to pass over the top.  Within this active flow, glass spheres, measuring 10 microns each, were added, a technique referred to as “seeding.”

The flume is outfitted with an instrumented carriage, staged above and across the width of the channel on rails.  A laser was attached to the carriage and positioned downward looking into the flow.  The scientists use the laser to accurately measure the water’s circulation pattern by tracking the neutrally buoyant reflective beads.  The velocity pattern and scallop ice layer created will be used to calibrate the numerical heat exchange model.

“Disturbance on the water surface interfered with laser velocity measurements,” said Leonard Zabilansky, a CRREL engineer providing facility oversight for this testing.  “The concept of the ‘glass bottom boat’ to optically couple the laser with the submerged scallops was developed by the NYU research team.  The concept evolved to an apparatus with a “V” hull to redirect entrained air bubbles away from the clear viewing area.”

The glass bottom boat was fabricated and later modified in CRREL’s Machine Shop as improvements were identified.

“This was a project that brought together many aspects of the flume’s features,” said Zabilansky.  “For example, the flume’s refrigerated bed replicated the ice-water-heat exchange process, and the 6,000 gallons-per-minute flow provided sufficient depth to develop the laser velocity system.”

With the experiment’s successful completion, there will be a better understanding of the temperature ratio between ice and water, a quantitative visualization of the flow field in ice scallop formation, and a data set that has not been produced before. 

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