New flumes give grad students cutting edge technology for studying water flow

Minimizing the impact of tsunamis on coastal regions and building sturdier bridges are just two of the outcomes a group of graduate student researchers are aiming for now that they have some top-notch new equipment up and running in the Ed Lumley Centre for Engineering Innovation.

“It’s really cutting edge,” PhD student Vimaldoss Jesudhas says of the giant flume he works with, one of two of its kind in the new engineering building.

Along with colleague Mehdi Heidari, the students use one of the flumes to study the characteristics of waves, and how vegetation in rivers and coastal regions affects the flow and velocity of water. Heidari said at one time, people thought vegetation in rivers and other waterways needed to be removed because it interrupted flow, but eventually realized removing it resulted in severe erosion, flooding and other environmental problems.

“We shouldn’t work against nature,” said Heidari, who works under the tutelage of civil and environmental engineering professor Ram Balachandar. “Nature is doing its work and we need to understand it.”

The flume they work on is something to behold. It’s a closed loop circuit that’s 18 metres long by 1.2 metres wide, capable of moving water through it a flow rates ranging 10 litres per second up to 150 litres per second. They’ll soon be installing a piston that will generate waves for further study.

Across the hall in professor Vesselina Roussinova’s lab, master’s students Sebastian Tejada, Carlo D’Alessandro and Priscilla Williams use a similar, but slightly smaller flume, to study the effects of sediment scouring on the massive piers that are mounted in riverbeds to secure bridges.

“More than half the bridge failures that we see are usually caused by scouring,” says Williams, “and that’s often brought about by a flooding event.”

Williams said it’s a phenomenon that’s factored in to the design of bridge before it’s constructed, but one that’s still not totally understood. Their flume has a box with sand in it, and a steel pier anchored in the centre. They can vary the water velocity from two to 70 litres per second and monitor how much sediment moves and how much scouring it causes to the pier.

“We’re trying to refine the research to see how different factors affect scouring, when compared with scouring calculated using current equations,” she said.

From left, Sebastian Tejada, Carlo D’Alessandro and Priscilla Williams stand beside the flume they use to study the effects of scouring on bridge piers.