chapter  Chapter 1
3 Pages

Introductory Remarks

WithAkira Yoshizawa, Sanae-I Itoh, Kimitaka Itoh

The theoretical study of turbulence in electrically nonconducting fluids has developed very differently from its counterpart of plasma turbulence. In fluid flows, the growth of disturbances imposed on the laminar state of each flow is investigated on the basis of linear and nonlinear stability analyses. In these analyses, the effects of global boundary conditions such as wall boundaries often play an important role, compared with the stability analysis of plasma micro-instabilities. When the laminar state is unstable, it is not unusual for initially small disturbances to evolve rapidly into fully-developed turbulent states. In the vicinity of a solid wall, a steep gradient of velocity is generated and this inhomogeneity of velocity field plays an important role in supplying small-scale flow components with energy. A fully developed state of turbulence is sustained by the continuous supply of energy, for instance, through the imposition of pressure. In this situation, the fully developed state of turbulence that is distinct from the initial stage of growing disturbances may be studied.