Wavenumber - Frequency Structure of Turbulent Flow in a Channel from a Direct Simulation

摘要

The detailed wavenumber frequency structure of the streamwise and wall normal components of the turbulent velocity has been obtained from a direct simulation in a channel. The turbulence is in an early stage of development but the features of the flow are qualitatively similar to the structure of fully developed turbulence. It is found from spectra computed in horizontal planes that wave speeds very near the wall are significantly higher than the local mean velocity and that the near wall streamwise velocity spectra exhibit a periodic structure. The spanwise length scale of this structure appears to correspond with the well known streak spacing observed in experiments. Detailed results of the wall pressure field reveal features which correspond closely with experiments in fully developed turbulence. Along with spectra obtained in the horizontal plane, the dependence of the correlations of wall-normal component of the turbulence on distance from the wall is presented. These correlations are directly related to a dominant source of wall pressure fluctuations.