Large Scale Structure in Turbulent Plane Couette Flow

Abstract

Large-scale structures appearing in core region of turbulent Couette flow have been studied in physical experiment. The behavior of low/high speed streaks were measured by hot-wire arrays in x1-x3 plane. The structures having length scale of (40 – 60)h in streamwise and (4 – 5)h in spanwise directions were detected from spectrum pattern in accordance with DNS results reported so far. Since the structures are disturbed randomly by the surrounding turbulent motion, the basic pattern of the large-scale structure cannot be detected hitherto. By extracting largescale modes out of the wavelet energy spectrum and reconstructing the flow field from them, the typical flow structure having inclined pattern along the streamwise direction can be obtained. This pattern does not appear uniformly in space but a sequence of it and void along the flow direction.