# Chorin Awarded Prestigious “University Professor” Honor By UC Regents

February 14, 2002

Dr. Alexandre Chorin, a founding member of Berkeley Lab’s Mathematics Department and a professor of Mathematics at UC Berkeley, has been honored with the title of University Professor by the Regents of the University of California.

The title of University Professor is reserved for scholars of international distinction who are also recognized and respected as exceptional teachers. It is a way to share their talents throughout the UC system for at least five years and no more than ten. Recipients are expected to teach and conduct research at campuses other than Berkeley. Other LBNL scientists who have been accorded this recognition include Marvin Cohen, Melvin Calvin and Glenn Seaborg.

"We are delighted that Alexandre is being recognized with his appointment to University Professor -- this honor is richly deserved,” said Pier Oddone, LBNL Deputy Director. “We at Berkeley Lab have greatly benefited from Alexandre’s leadership of our applied mathematics program and are enormously proud of his achievements -- both in his mathematical innovations and in his spawning whole generations of mathematicians in the Chorin mold!"

Chorin, whose colleagues consider him one of the great applied mathematicians of the 20th century, already travels widely to speak and to teach. He expects to continue to do so among UC's 10 campuses -- with the added distinction of being one of only 22 faculty members so honored in the system. Nine of them are at UC Berkeley.

"You're supposed to go around and talk to people on other campuses, but I do that anyway," said Chorin.

Chorin, 63, is a native of Poland who grew up in Israel and Switzerland, making his way to New York in 1962 and eventually to UC Berkeley in 1971. He specializes in scientific computing, numerical analysis and computational methods of statistical mechanics, though his true love is the most difficult problem of applied mathematics: turbulence -- the chaotic eddies and currents in any fluid that are hard to study experimentally and harder still to calculate mathematically.

For more than 30 years, Chorin has worked to develop computational methods for solving problems in fluid mechanics, with the hope that they will eventually lead to an understanding of turbulence. What makes the turbulence problem so compelling, in addition to its practical importance, is that the basic equations that describe turbulence are well known and simple, yet their solutions are incredibly complex and the computing power needed to find them transcends any imaginable computer, according to Chorin. Research into turbulence has applications across a broad range of areas of importance to DOE. These include combustion, energy efficiency and fusion energy.

"I'm very interested in turbulence, but turbulence is a very hard field -- if you work ten years and get something small, it's big progress," Chorin said. "You really have to have knowledge in lots of other fields, and you have to do other things also if you ever are going to get satisfaction."

In his early years, he developed computational methods and computer software that were used widely in the aircraft industry to mathematically model air flow over airplane wings. The general techniques are still employed, though Chorin moved on to apply his methods to a large variety of other fields -- water flow in oceans and lakes, flow in turbines and engines, combustion, flow in the heart and veins. These are just a few of the applications he has explored in more than 90 papers.

A recent result he is proud of involved collaboration with colleague Grigory Barenblatt, a member of the Lab’s Mathematics Department and professor of mathematics at UC Berkeley. They discovered that a long-used rule of thumb that lets engineers predict the forces generated by turbulent flow over a wing or other surface breaks down at high velocity. They have proposed better methods to approximate the force exerted on a wall or surface by turbulent flow, and continue to explore the implications and to understand the mathematics of fluid flow.

Another area of Chorin’s research today involves computations that are incomplete.

"There are lots of problems where you have no hope of doing a complete calculation," he said. "There is too much complexity or too many unknowns, or you are not certain of what the equations are, or the problems have intrinsic uncertainty -- turbulence is one of them. The project I am working on is, suppose the calculations you can do are limited, what's the best you can say? What conclusions can you legitimately draw from it?"

Two years ago, the Society for Industrial and Applied Mathematics and the American Mathematical Society honored Chorin with the 2000 Norbert Wiener Prize, one of the highest distinctions in applied mathematics. The prize citation states that Chorin's work “has stimulated important developments across the entire spectrum, from practical engineering applications to convergence proofs for numerical methods."

Chorin obtained his Ph.D. from New York University in 1966 and conducted research at that institution's Courant Institute. After a year as a Visiting Miller Professor at UC Berkeley in 1971-72, he decided to stay. He is a member of the National Academy of Sciences and a fellow of the American Academy of Arts and Sciences. Among his honors is the National Academy of Sciences' Award in applied mathematics and numerical analysis. He has previously been recognized for his academic talents by being named Chancellor’s Professor of Mathematics and has been elected by the UC Berkeley Academic Senate as a Campus Research Lecturer.

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