Phase Angle Considerations in the Modeling of Intermittent Turbulence

Abstract

It has been suggested that the study of phase angles associated with the Fourier transforms of time series may yield information about the intermittent behavior of turbulent records. It is shown with numerical experiments that the phase angles and the fine-structure of the spectrum are both associated with the intermittency. The phase angles of turbulence appear to be nearly independent and uniformly distributed in the same sense that the spectrum has an approximate ?5/13 power dependence on the wavenumber. But neither of these approximate models account for the observed intermittency. The intermittency therefore bears some relation to a higher order structure in Fourier space. The nature of this structure has not been found explicitly, although a qualitative explanation is offered.