Dresden 2009 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 16: Fluid dynamics I

DY 16.7: Vortrag

Mittwoch, 25. März 2009, 16:30–16:45, ZEU 255

Numerical simulations of localized turbulence in shear flows — •Marc Avila and Bjoern Hof — Max Planck Institute für Dynamik und Selbstorganisation, Bunsenstraße 10, 37073 Göttingen, Germany

Subcritical transition to turbulence in shear flows has been recently interpreted in terms of novel developments in low-dimensional dynamical systems theory. At moderate Reynolods numbers, the flows are characterized by the presence of turbulent patches which are bounded by laminar regions. On the theoretical side, these states have been linked to the presence of a chaotic saddle embedded in the infinite-dimensional phase space of the Navier-Stokes equations. Experiments and numerical simulations show that at low Reynolds number localized turbulent states are transient, their lifetimes following and exponential distribution in accordance to theoretical predictions. However, conlifcting views are held in the community as to the transient behaviour of turbulence when the Reynolds number is increased. Instead, the focus of this contribution is on the understanding of the physical mechanisms feeding localized turbulent states. Numerical simulations are conducted in order to obtain pressure and vorticity distributions, as well as propagation speeds. Particular attention is paid to the spatial resolution requirements that need to be met in order to faithfully resolve the nonlinear dynamics.