The Relationship Between the Large-scale Structures and Bursting Phenomenon in Turbulent Boundary Layer

Abstract

In this study, the relationship between the Large-scale structures and bursting phenomenon was investigated by the simultaneous measurement of streamwise velocity in the logarithmic region and the buffer region in a turbulent boundary layer using multi-channels hot-wire probes. Superstructures (SSs) were detected in the logarithmic region whereas bursting phenomenon was detected in buffer region. Furthermore, the superstructures were divided into the high speed Superstructure (pSS) and the low speed Superstructure (nSS), respectively, and both of their impacts on the bursting phenomenon were investigated. As a result, it was found that the presence of SSs has an effect on the amplitude of the bursting waveform. In addition, the packet of large scale hairpin vortices straddling the SS was observed, suggesting that the detected bursting phenomenon includes those generated with large scale hairpin vortex. A further investigation shows that different sizes of hairpin vortices could be identified when the bursting phenomenon occurring.