The plane mixing layer flow visualization results and three dimensional effects

摘要: Abstract : The turbulent mixing layer between two streams of different velocities continues to play a central role in research aimed at improved understanding shear flows general. At present, not all researchers are agreement as what various experiments imply about the structure layers high Reynolds number. views which held differ on question how and extent three dimensionality develops these whether characteristic spanwise organized large vortex structures (rollers) continue be dominant feature. traditional view, extended contemporary scene, is that ultimately (i.e., sufficiently far downstream or number) flow will completely disorganized. view put forward by 'eddy chasers' such primary elements, underlying mean vorticity field, particularly simple for layer, that, long velocity difference maintained, there mechanism regenerate what, convenience, may called Kelvin-Helmholtz instability. heart controversy then whether, extent, secondary higher instabilities break down, disorganize prevent formation structures. In plane would, ideally, dimensional, containing basic single component while modes instability would introduce other components into flow. (Author)