Ewoldt to join MechSE faculty

For the 2011-12 academic year, the MechSE department will increase its number of faculty to 54 with three new assistant professors. One of them is known, by the Society of Rheology, as the snail guy.

New Assistant Professor Randy Ewoldt specializes in non-Newtonian fluid mechanics and Rheology. Non-Newtonian fluids often combine both fluid and solid behavior, existing as substances somehow between those two areas–like hair gel and snail slime. Such squishy materials are ubiquitous in nature, and Ewoldt likes to take ideas from nature to discover fundamental principles that can be used with engineered systems.

“I try to understand non-Newtonian fluids from a fundamental level and also use them for applications,” Ewoldt said.

He develops mathematical models and experimentally studies the physics of complex fluids and soft materials. Snails climb walls by sticking to an excreted yield-stress fluid; this is a material that is a sticky solid at rest but then becomes a slippery fluid when a sufficient amount of stress is applied. As a graduate student at Massachusetts Institute of Technology (MIT), Ewoldt used his analysis of the fluid to replicate snail-like wall climbing with a mechanical-engineered device, with the help of fellow student Brian Chan. Because blood acts similarly to non-Newtonian fluid such as snail slime, knowing how to make little machines move in the substance could lead to the development of high-tech medicine like remote-controlled chemo or targeted blood vessel repair.

“We are looking at a lot of other biological materials as well that have really peculiar properties and may be useful if you were to apply them in an engineering material or an engineered device,” Ewoldt said.

For example, Ewoldt took a cue from nature based on hagfish. He describes them as disgusting creatures that live at the bottom of the ocean, but with a fascinating defense mechanism. Hagfish excrete a small amount of material, and then create a turbulent flow to expand the substance by a factor of about a thousand. This causes the material to form a fibrous net gel and clog the gills of suction feeding predators.

“In biology, this serves the function of clogging up something,” Ewoldt said. “So you start to think, are there any sorts of pipes that you might want to clog with a small amount of material?”

Ewoldt received his bachelor’s degree in mechanical engineering from Iowa State University and then completed his masters and doctorate degree in mechanical engineering from MIT. He now works as a postdoctoral research fellow at University of Minnesota-Twin Cities, at the Institute for Mathematics and its Applications. His appointment coincided with a year-long thematic program on complex fluids and complex flows.

“The work that I have started here has been both theoretical and experimental,” Ewoldt said. He has already been comparing some of his experimental results with Illinois MechSE Professor David Saintillan.

Ewoldt said that Saintillan has done some really nice theoretical modeling to predict how viscosity should change when you add actively swimming particles to fluid, like microalgae used for algal biofuels. With careful experiments his recent work reveals experimental results to compare with Saintillan’s modeling.

Another connection that ties Ewoldt to Illinois is Illinois alumnus Michael Olsen. Olsen is a professor at Iowa State University that Ewoldt first worked with for undergraduate research.

When it comes to location, Ewoldt has strong Midwest connections; he was born in Davenport, Iowa and his mom is from Joliet, Illinois.

“This is a dream job with a great location; an amazingly strong department and institution that is conveniently located near my family,” Ewoldt said.

Ewoldt starts as an assistant professor at Illinois in Fall 2011. For the first semester, he will focus on building his laboratory. During the second semester, he will help teach fluid mechanics. He soon hopes to start a special topics course in non-Newtonian fluids and rheology. Ewoldt is assembling a lot of experimental equipment and instrumentation in his lab which should connect to interests across the engineering college and other departments, such as a rheometer–a device that measures the way materials flow and deform in response to applied forces.

Chris Macosko, professor of chemical engineering and material science at the University of Minnesota and Ewoldt’s postdoctoral adviser said, “The nicest experience I had with him was when we taught for two years in a row a graduate rheology course. I got to listen to his lectures and learn some new teaching ideas.”

When Ewoldt starts he hopes to jump into studying the excretion of oil that microalgae produce, which can be used as a precursor for biofuel. He emphasizes the joy and fun that he has in studying these peculiar fluids. Ever since high school, Ewoldt has felt comfortable and wired to be a professor.

“I really like the challenge of trying to take technical ideas and somehow communicate them concisely to other people, not just people at University but even family and friends,” Ewoldt said. “I have a three-year-old son and I love teaching him all these science ideas and the challenge of trying to distill it down to something that even he can understand is a lot of fun.”