SCALE-SEPARATION IN BOUNDARY LAYER THEORY AND STATISTICAL THEORY OF TURBULENCE

摘要

The idea of the "boundary layer" proposed by Prandtl [1] does not only provide us with a powerful means foi solving various flow problems at large Reynolds, but also furnishes us with a universal concept for dealing with the problems of the same nature in physical sciences This is the "scale-sepaiation" which guarantees the independence of the local motions from the global structure In this paper, a clear parallelism is pointed out between the "boundary layer" in laminar flows on one hand and the "local equilibrium range" in turbulence on the other The statistical characteristics of homogeneous isotropic turbulence at large Reynolds numbers are surveyed, using the recent results by Tatsumi & Yoshimura [2] covering both the energy-containing and the local equilibrium ranges, and comparative discussions are made from the view point of the scale-separation.