A wave crashes into the coastline, driving water onto the shore and then stealing away sand, soil, rocks and more.
For Nimish Pujara, an assistant professor in the Department of Civil and Environmental Engineering at the University of Wisconsin-Madison, investigating the fundamental processes behind such an event can lead to bigger-picture lessons that could inform how we develop, manage and protect coastal areas.
“If you understand how much sand is picked up or how much flow is driven onto the land when a wave crashes at a beach, then you can understand how it might change with different conditions and if you build something there, what sort of impacts it would likely have,” he says. “And you can then try to develop a bigger picture of how the system behaves.”
Pujara, who joined the College of Engineering in August 2018, studies fluid mechanics in environmental contexts and how turbulent flows behave in the natural world. By using long, narrow wave tanks to simulate natural events, he can generate wave pulses and then measure metrics like flow speed, depth, friction and pressure. As a PhD student at Cornell University, where he dove deep into coastal hydrodynamics, Pujara helped develop a sensor to measure friction levels throughout such a flow as part of a project to better understand erosion caused by waves.
At UW-Madison, he’s reviving a laboratory with a dormant wave tank in the Water Science and Engineering Laboratory on the shore of Lake Mendota, a short walk from the Memorial Union Terrace.
“I like being in the laboratory,” he says. “In my experience, in a well-designed laboratory experiment, there’s always something new for you to learn that you didn’t know. You can ask a very simple question and go down to the lab and test it and you will learn something new.”
Indeed, Pujara’s intellectual curiosity was what drew him to his field in the first place. Though he grew up in a region of India that borders the Arabian Sea and spent his adolescence in the Netherlands, a country whose coastlines are under constant threat from the North Sea, water didn’t truly capture his attention until he took courses in fluid mechanics as an undergraduate at the University of Cambridge in England.
“From there, it was, ‘I like this stuff, I’d like to understand it better—and that’s why I want to do a doctorate.’ It was mainly so I could sink my teeth into it further,” he says. “I decided to go the environmental route, because I thought, ‘Well, there it seems like almost nothing is understood.’ It’s so complex, things change from case to case, but there must be some underlying phenomena where the physics is the same, and that’s what I try to work out.”
In his doctoral work, Pujara drew heavily on theories that were presented at a seminar on the UW-Madison campus in 1971 and collected in the book Waves on Beaches and Resulting Sediment Transport, edited by the late UW-Madison mathematics professor Richard Meyer.
Little did Pujara know he too would wind up in Madison, after spending three years as a lecturer and postdoctoral researcher at the University of California, Berkeley. In fall 2018, he’ll teach Mixing and Transport in the Environment, a new special topics course for first-year graduate students and advanced undergraduates that covers how contaminants and other solutes spread in water.
“I like interacting with students in small groups,” says Pujara, who plans to build time for small-group discussion into every course he teaches. “Early on in a semester, if some concept doesn’t quite click and you keep building on it, that’s where you lose people. Whereas if you’re in a small group, you can talk through that and clarify it. That can change the whole trajectory of how a semester goes for any given student.”