We are greatly saddened by the sudden passing on April 14 of Keith Julien, Chair and Professor of Applied Mathematics at the University of Colorado, Boulder, Fellow of the American Physical Society, and a member of the Editorial Board of Physical Review Fluids.
Dr Julien made many fundamental contributions to the fields of geophysical and astrophysical fluid dynamics as well as applied mathematics in general. In his career, he examined a wide range of instabilities and turbulent phenomena occurring in stratified flows as influenced by rotation and magnetism, including the dynamics of convection, magnetoconvection, dynamos, the magnetorotational instability, and double diffusive convection. Much of his work involved state-of-the-art numerical simulations and the development of novel numerical algorithms, particularly involving spectral methods. To gain insight into the phenomena observed, he promoted the application of multiscale asymptotic methods to turbulent flows subjected to strong restraints, culminating in reduced sets of partial differential equations that captured the essential dynamics. He is perhaps best known for the application of these innovative and valuable tools, which are now more widely used by the fluid dynamics community, particularly to the phenomenon of rapidly rotating, buoyancy-driven convection.
As well as pioneering such mathematical advances, Dr Julien selflessly nurtured the next generation of scientists via his supervision of graduate students and postdoctoral fellows. As Chair of the Department of Applied Mathematics, he worked tirelessly to advance the impact of its programs and to build a strong community, particularly among undergraduate and graduate students. He always approached his work with purpose, equanimity and steadfast resolve, but yet with humor.
Our thoughts are with his wife, Susan, and sons, Simon and Theodore. You were taken too soon, Keith. You will be sorely missed.
