Benoît Pausader uses partial differential equations to make mathematical models of waves and other physical systems. He admits that the path he followed into this line of work was not always smooth sailing.

“I took a course in partial differential equations in college and found it extremely hard to follow,” he said. “But because of that I really had to study and I ended up loving it. I just had to suffer a bit to get into it.”

Once he got past the suffering, Pausader quickly flourished. He’s held appointments at New York University, the Centre National de la Recherche Scientifique in France, and most recently at Princeton. He has been the recipient of two grants from the National Science Foundation and was named a Sloan Research Fellow in Mathematics in 2014.

His new position, associate professor of mathematics, marks his second appointment to the Brown faculty. In 2007, Pausader had published a section of his thesis titled Scattering and the Levandosky-Strauss conjecture for fourth-order nonlinear wave equations. Walter Strauss, professor of mathematics at Brown and half of the Levandonsky-Strauss duo, saw the paper and invited Pausader to Brown to continue the work. That invitation led to a three-year appointment as a Tamarkin assistant professor from 2008 to 2011.

Over those first three years at Brown, Pausader’s research focus expanded. He started talking with Yan Guo, professor of applied mathematics. Guo works with fluid models in plasma physics, and he helped interest Pausader in working in that area as well.

“It was natural,” Pausader said of his work with Guo. “He works in partial differential equations and so do I. So we had a connection.”

Now that he’s returned to Brown for a second time, he’s hoping to find new collaborators, new systems to model, and new questions to explore.

“I’m always amazed at the extent to which I can see physical phenomena reflected in the math, the extent to which mathematics can reflect reality,” Pausader said. “In some sense, that’s what keeps me interested.”

And he says he’s pleased that this new chapter in his career brings him back to Brown.

“I love Brown,” he said. “I find the people very friendly and it’s a nice atmosphere in the math department. There were good incentives to want to be here and I’m glad to be back.”