Regensburg 2019 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 18: Fluid physics and turbulence
DY 18.1: Hauptvortrag
Dienstag, 2. April 2019, 10:00–10:30, H20
Bursting, amplitude explosions and mixed mode oscillations at the onset of shear flow turbulence — •Björn Hof1, Chaitanya Paranjape1, Yohann Duguet2, Vasudevan Mukund1, and Nazmi B Budanur1 — 1IST Austria — 2LIMSI-CNRS
In pipe and channel flows turbulence appears abruptly and the dynamics is immediately high dimensional. Where exactly turbulence originates from and how the turbulent patches characteristic for low Reynolds number turbulence develop has remained an open question for over a century. I will here discuss the different stages of the transition process starting from spatially localized exact coherent structures. In particular I am going to highlight the interplay between the fast fluctuation time scale and the slow recovery of shear, inherent to these structures. Following an explosive increase in fluctuation amplitude, a sharp rise in the attractor dimension is observed and subsequently a boundary crisis to transient chaos. This transition scenario results in localized turbulent transients that through interaction become sustained at a directed percolation phase transition.