Turbulence, which appears ubiquitously in nature, is one of the fundamental problems of fluid dynamics, and is characterized as a typical nonlinear, non-conservative, and statistical phenomenon. The present seminar will illustrate the basic physics of turbulence for the general audience, focusing on the closure problem and the Kolmogorov theory of fully developed turbulence. It will also introduce briefly how various concepts of statistical physics have been applied to explain turbulence, such as kinetic theory, fractal, chaos, and the RG method.

In spite of difficulty of understanding turbulence theoretically, there have been extensive attempts to simulate turbulence for practical purpose. Recently highly realistic simulations of turbulence have been accomplished with the helps of increasing computing power and the improved methods of representing turbulence, such as large eddy simulation (LES). The basic concept of LES and its implementation to parallel computing will be described. It will also show how the simulation results can be used to understand and predict turbulence in the atmosphere and ocean.