COLLABORATION IN BASIC SCIENCE AND ENGINEERING (COBASE)

Sergei Danilov and David Gurarie

Sergei Danilov of the Russian Academy of Sciences Institute of Atmospheric Physics (Moscow) made two three-month visits to his U.S. host, David Gurarie, in December 1999-February 2000 and April-July 2000. The site of both visits was the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, where Gurarie was on leave from his position on the faculty of Case Western Reserve University. During the visits, the two colleagues pursued an extensive theoretical and numeric study of two-dimensional turbulence, a classical problem in fluid dynamics with numerous applications to geofluids. Using a pseudospectral code developed by the visitor, they conducted a series of numeric experiments on two-dimensional turbulence subject to small-scale forcing and frictional and viscous dissipation. Based on the results of their experiments, which deviated dramatically from theoretical predictions, they have proposed some new approaches to the inverse cascade turbulence problem.

Gurarie reports that the visits gave him the opportunity to learn some new computational tools and techniques for large-scale numeric simulations of complex fluid systems and the physics and geofluids. Meanwhile, Danilov benefited from his host’s theoretical and mathematical expertise in the are of novel approaches based on mathematical tools (dynamical systems, multiscale and stochastic analysis, etc.)

Seven publications have already resulted from this productive collaboration, and Gurarie and Danilov have submitted two proposals to continue their study of two-dimensional turbulence and expand its scope to more complicated geophysical systems (one and multi-layer quasigeostrophy, shallow water, etc.). One of the proposals has already been funded by NCAR’s Geophysical Turbulence Program, while the other is still under review at the National Science Foundation.