Structure des perturbations dans une couche limite turbulente : zone interne
Résumé
Measurements of spatiotemporal correlations of fluctuations of temperature at three points are carried out to determine the structure on a large scale of the internal zone of a boundary layer which on the average is two-dimensional. It is shown that perturbations of air exist, conservative along the mean and three-dimensional motion, the lateral coherence of which is less than the thickness of the boundary layer. The comparative study of double and triple correlations shows the existence of two statistically dominant principal modes: one corresponds to perturbations coming from near regions of the wall, the other from near regions of the external flow.