Recent progress in the physics of turbulence: theory, simulation and i…

" 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 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 attemptsto simulate turbulence for practical purpose. Recently, highly realistic simulations of turbulence have been accomplished with the helps of increasing computing power and the improved technique of representing turbulence, such as large eddy simulation (LES). The basic concept of LES and its implementation to parallel computing will be described. Finally, LES results of various geophysical turbulence phenomena will be presented with the applications to their parameterizations in the large-scale geophysicalmodels. Using the LES of the ocean mixed layer, we investigate the roles of wave breaking and Langmuir circulation, and examine the parameterizations used in the ocean mixed layer models. The LES of the motions of a large number of Lagrangian particles inthe ocean mixed layer helps us to clarify the particle settling process in the upper ocean, which plays an important role in the carbon cycling in the ocean by way of the biological pump. The LES of the atmospheric boundary layer is used to develop a new PBL model, and the LES of open ocean deep convection is used to determine the criterion of baroclinic instability "