They'll do solid research on liquids

UNC fluid dynamics lab eager to catch waves in new tank

CHAPEL HILL -- A group of researchers is making waves at UNC-Chapel Hill.

At least, they will be soon.

A giant, 136-foot-long wave tank is coming to the cavernous basement of Chapman Hall, which was dedicated in November.

The wave tank, expected to be ready in December, will be the centerpiece of a greatly expanded fluid dynamics lab at UNC-CH.

"This facility used to be upstairs in a closet," said mathematician Rich McLaughlin as he waved his hand around the 4,500- square-foot room where approximately 10 students and faculty worked on experiments.

Marine sciences professor Alberto Scotti is looking forward to using parts of the lab to demonstrate principles for his fluid dynamics classes. "Until this semester I had to wave my hands," he said.

Initially the researchers will be using the wave tank to study internal waves between the layers of lighter and denser water found in the ocean, said mathematician Roberto Camassa.

Those internal waves have some relationship to global warming, Camassa said, "although we don't know quite what."

They also play a role in the distribution of marine life, which is of interest to the marine fisheries industry, Scotti said.

Some of Scotti's research is funded by the Navy, which is interested in how sound moves through layers in water.

The lab's work is supported by grants from the National Science Foundation, McLaughlin said, including a $1.7 million research training grant.

The wave tank itself, funded with a $620,000 grant from the NSF, is being designed by a firm in Pennsylvania. Since it wasn't part of the original Chapman Hall plan, each section of the 136-foot-long tank will have to be brought down in an eight-foot-square freight elevator, said Scotti. The space was a happy accident, he said -- during the excavation of the foundation, builders overestimated the hardness of the bedrock and made a larger basement than the original plans called for.

The tank is unique, researchers say, because of its design. It can be divided into modules to accommodate different experiments, or the entire length can be opened up for larger-scale work. A computer-controlled paddle system will produce the waves.

"We can actually try to model the effect of a tsunami," said Scotti, "even though tsunamis aren't much of an East Coast concern."

The sections have different dimensions, making for greater versatility. One is "basically a beach section," said McLaughlin, and the researchers may at some point install simulated ocean bottom or aquatic plants. That would allow them to look at how waves and beach topography affect erosion in coastal areas and could have implications for beach-nourishment projects, Scotti said.

The tank, holding 10,000 to 15,000 gallons, will be raised off the floor, allowing researchers to observe fluid motion from all sides. The walls are of a clear acrylic that won't distort light or color. There are larger wave tanks, but they're not designed to be viewed from all directions, McLaughlin said.

Researchers in the fluids lab also investigate questions with applications on much, much smaller scales.

They work closely with colleagues from the medical school and nanoscale physicists to understand fluid transport in the human body, like in the lungs and heart.

One experiment under way seeks to model aspects of the circulatory system and heart. Faculty member Laura Miller is studying how the embryonic heart develops before birth. Eventually, researchers hope, the experiments will give them insight into conditions like congenital heart disease.

"It's thought that some of these could be corrected basically using fluid surgery," Miller said.

But it's the wave tank the researchers are most excited about, lighting up like kids who already know what they're getting for Christmas.

"I'm ecstatic. This is one of the coolest, best labs that I could have dreamed of. We're sky-high about it," McLaughlin said.

"It's opening new doors for us."