Flooded with findings
By Jacqueline R. Koch
What started as a research project for a national laboratory led to innovative and creative ways using ground coffee and underwater lighting to measure water depth and velocity for mechanical engineering students at Bradley University.
Scientists at Los Alamos National Laboratory were interested in learning how floodwater affects buildings and cities, but had no way to validate the data they collected. So last fall, Bradley students used a large, blue water table in the fluid mechanics laboratory to collect data regarding water velocity and depth.
Boxes in the water represented single buildings, whereas checkerboard arrays of boxes represented cities. Water in the table rushed past the buildings at different velocities and depths to determine the flood’s impact.
“They’re trying to predict what will happen if there’s a flood,” senior mechanical engineering student Emily Larsen says.
Larsen and other students who participated in the project presented their findings to a faculty panel. After one of the panel evaluations, Dr. Martin Morris, a mechanical engineering professor, suggested that students measure water depth by illuminating the water from below the surface.
So students lit the water from the bottom of the table and inserted green dye into the water to block the light. A camera captured images of different light intensities, which correlated with depth. In other words, the darker the water, the deeper it was. An electroluminescent sheet on the bottom of the water table provided uniform lighting.
“It worked better than we’d expected,” Dr. Morris says. “It was a real challenge to design a safe system with a dry panel that would measure water depth.”
Students previously had inserted probes into the water and took measurements at various points to determine depth. The process was tedious. The new method allowed for the collection of millions of data points that showed an almost continuous depth measurement across the field.
“Nobody has done it this way that we know of,” Dr. Morris says.
But the students weren’t finished. They also found an innovative way to measure the water’s surface velocity. Previously they’d inserted white particles into the water and allowed them to float with the current to measure velocity. Creating uniform particles, however, was difficult. So students decided to dye the water white and float dark coffee grinds through it. Students ground coffee beans to various sizes and then tracked the particles’ movement with a camera, which collected images as the grounds moved through the water.
“It worked really well,” Dr. Morris says. “It was an innovation that the students came up with that helped deliver some really nice surface velocity measurements. It was a great idea. I’d never thought about doing it.”
"I don’t think anybody has measured water this way. It provides an awful lot of data."
mechanical engineering professor
Dr. Morris expects others to follow suit when measuring water depth and velocity, though the students’ methods have not yet been applied elsewhere.
The water table, which has been at Bradley for many decades, helps provide up-to-date information and research for students and professors. The table is 4-feet-wide by 20-feet-long by 4-feet-high and consists of water and a pump. Even though the table was used more often before the emergence of computers and technology, fluid mechanics students are attempting to make the pump relevant for the modern era. So far, it’s been incredibly successful, Dr. Morris says.
He hopes to write up the students’ methods and publish them because he thinks other researchers could benefit from the methods. Finding external funding could allow the project to find even more uses on campus and around the Peoria area. And the data collected is being submitted back to the Los Alamos National Laboratory, which is responsible for innovation and research regarding national security, computing, health, science, the Earth, and the universe.
Even students in other fluids classes will benefit from the project. They’ll also use coffee particles to measure water surface velocity.
“I don’t think anybody has measured water this way,” says Dr. Morris, who gained previous experience working with pressure sensitive paints and light intensities to determine water depth. “It provides an awful lot of data.”
Because students deal with budgets and deadlines for their senior projects, they have an advantage when they apply for jobs. The water table project provides students with even more of an advantage. Students benefit not only from designing a project but also from researching data for a national laboratory. The research continued after the semester and through the summer.
Larsen says she gained experience in researching, as well as in finding creative solutions.
“I learned a lot about the different kinds of processing for fluid mechanics and about problem-solving,” she says. “It’s been very interesting.”