Among the many organized structures observed in near-wall turbulent flows, streaks, defined as regions of slowly moving fluid elongated in the direction of the mean flow, are considered to be of major importance for their role in the regeneration of turbulent energy. Here, we identify and track individual streaks in time using time-resolved direct numerical simulation data of a low Reynolds number channel flow. The analysis of the streaks shows that there is a clear distinction between wall-attached and detached streaks, and that the former can be further categorized into streaks that are contained in the buffer layer and the ones that reach the outer region. The results reveal that streaks are born in the buffer layer, coalescing with each other to create larger streaks that are still attached to the wall. These large tall-attached streaks eventually split into wall-attached and wall-detached components, which are strongly related to ejections or burst events.
Jane Bae is an Assistant Professor of Aerospace at the Graduate Aerospace Laboratories at Caltech. She received her Ph.D. in Computational and Mathematical Engineering from Stanford University in 2018. She was a postdoctoral fellow in the Graduate Aerospace Laboratories at Caltech and the Institute for Applied Computational Science at Harvard University before joining the Caltech faculty. Her main research focuses on computational fluid mechanics, in particular on modeling and control of wall-bounded turbulence.