Wednesday, February 2, 2011

New Faculty Profile: Shreyas Mandre

Shreyas Mandre
Assistant Professor of Engineering

Shreyas Mandre

Assistant Professor of Engineering
Credit: Mike Cohea/Brown University
By Richard C. Lewis 

It seems as if Shreyas Mandre has a fascination with the familiar. Take, for instance, the splash made by a falling droplet of water, or consider the basso notes that come from blowing across the rim of an empty bottle.
Not only does Mandre, assistant professor of engineering, take note of such ordinary happenings, he has sought to explain them.
“I don’t know at what point we lose that [ability to be] surprised,” he said.
It’s a good thing, because what appears to be a simple act in nature is not so elementary after all. Such is the case with the splash generated by a liquid striking a surface. Mandre, in a paper published last year, explained through a model that a thin layer of air is compressed by the falling droplet a few microseconds before it hits the surface. This creates an air cushion that causes the raindrop to flatten and spread out, Mandre discovered.
Mandre’s study of the noise that comes from blowing on an empty bottle has more personal roots. Growing up in Mumbai, Mandre recalls his childhood frustration with playing the flute.
“I could make a sound from it now and then, but I never learned it properly,” he said, “so it was natural for me” to figure out what caused the sound to be created.
He substituted a bottle for the flute and found that the sound production revolves around acoustic and elastic vibrations interacting with fluid flows. The fluid flow in this case is the blown air, while the vibrations come from the sound bouncing off the narrow cylindrical walls of the bottle. The mathematical models he presented as part of his doctoral thesis show precisely how that all occurs.
Our voices operate on the same principle: The fluid (air) is traveling through an elastic body (our vocal folds). The applications are many, from helping geologists to understand the flow of molten material below the Earth’s surface and thus perhaps predict volcanic eruptions to building airplane wings that are less prone to vibration.
“All of these things have in common a body that is capable of oscillating or resonating and a flow, which is responsible for exciting the oscillations,” Mandre said.
Mandre, 31, comes to Brown from Harvard University, where he taught applied mathematics. He received his undergraduate degree at the Indian Institute of Technology, his master’s in mechanical engineering at Northwestern University, and his Ph.D. in mathematics at the University of British Columbia in Vancouver.
He and his wife, Radhika, are living in Providence.