Coherent Fine Scale Structure in Turbulence

Abstract

The understanding of fine scale structure in turbulence is very important in the development of turbulence theory. In the theory of fine scale motion in turbulence, tube-like vortices are frequently assumed to represent the phenomenon of intermittency (Townsend, 1951; Tennekes, 1968; Lundgren, 1982; Pullin and Saffman, 1993; Saffman and Pullin, 1994; Hatakeyama and Kambe, 1997). Recently, direct numerical simulations of the turbulent flows have shown that similar tube-like structures can be observed by the visualization of intense vorticity regions in turbulence (Kerr, 1985; She et al., 1990; Vincent and Meneguzzi, 1991; Ruetsch and Maxey, 1991; Jimenez et al., 1993). In this study, the universality of the fine scale structure is discussed by analyzing DNS database of various turbulent flows. Fine scale eddies in homogeneous isotropic turbulence, turbulent mixing layer, turbulent channel flows and MHD homogeneous turbulence are compared to show the scaling law of the tube-like structures in turbulence. The relationships between coherent fine scale eddy and the characteristic length of turbulence are also discussed in homogeneous isotropic turbulence.