Yannis George Kevrekidis, the Pomeroy and Betty Perry Smith Professor in Engineering, professor of chemical and biological engineering, and senior faculty in the Program in Applied and Computational Mathematics, will be transferring to emeritus status on July 1, 2017, after thirty-one years on the Princeton University faculty.

Yannis (as he is commonly known) was born in Athens, Greece, in 1959. He received an undergraduate (five year) degree in chemical engineering from the National Technical University of Athens in 1982, and an M.A. in mathematics and Ph.D. in chemical engineering from the University of Minnesota in 1986. His doctoral advisers were Rutherford Aris and Lanny Schmidt, and his thesis was “On the Dynamics of Chemical Reactions and Reactors.” He was appointed assistant professor in the chemical engineering department of Princeton University in 1986 and was promoted to associate professor in 1991, and to professor in 1994.

Research in Yannis’s group has focused on the dynamic behavior of chemically reacting systems, and the development of innovative computer-assisted techniques for modeling engineering processes. At the beginning of his career, he studied nonlinear dynamics, instabilities, spatiotemporal pattern formation, and bifurcations in chemically reacting systems. He pioneered the fabrication and exploration of microdesigned addressable catalysts, in collaboration with the group of Gerhard Ertl, the 2007 Nobel Laureate in Chemistry, at the Fritz Haber Institute of the Max Planck Society in Berlin, and invented a systematic approach to reveal new knowledge through computation in complex, multiscale reacting systems—his equation-free framework. In a pioneering Science paper in 1994, the use of microlithography to construct controlled size/geometry domains on single crystal catalysts was introduced; this experiment, motivated by and designed through theory, marked the beginning of a fertile collaboration with Ertl. The work was coupled with the development of novel resolved surface microscopy techniques that enabled an unprecedented link between experiments and computer modeling. In 2001 came a breakthrough: construction of the first microaddressable catalytic surface, where sensing (through resolved surface microscopies) and actuation (via laser beams manipulated through galvanometer mirrors) were coupled at an unprecedented spatiotemporal resolution.

Yannis’s equation-free modeling constitutes an extraordinary body of work that started to appear in 2000. It brings a systems engineering, input-output approach to the way complex simulations are performed and processed. Yannis’s simple, yet seminal, idea is to treat atomistic or fine-scale simulators as experiments that can be designed, initialized, and run at will. The derivation of macroscopic equations is circumvented, and systems-level modeling tasks (prediction, stability analysis, and control design) are performed directly through efficient and judicious use of the fine-scale model (e.g., using short simulation “bursts” to evaluate numerically the derivatives of macroscopic observables). The approach has remarkable generality; bridges continuum modeling, applied mathematics, and scientific computation with microscopic/atomistic physics approaches; and is transforming the way complex, multiscale systems are being modeled—a vital interdisciplinary research frontier. Example applications include accelerating convergence and obtaining stability information for process simulators, kinetic Monte Carlo simulations for catalytic surface reactions, multiphase flow and plasma modeling problems, liquid crystals, micelle formation, cell motility, and more.