Dresden 2011 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 23: Nonlinear Waves/ Nonlinear Lattices

DY 23.4: Vortrag

Mittwoch, 16. März 2011, 15:00–15:15, ZEU 255

A Coupled-Map Lattice Model for the Puff-Slug-Transition in Turbulent Pipe Flow — Christian Marschler and •Jürgen Vollmer — Max Planck Institute for Dynamics and Self-Organizaton, 37073 Göttingen

Pipe flow shows long-lived localised turbulent regions (puffs) that are convected down the flow when increasing the Reynolds number Re =U L/ν beyond Re ≳ 1500. Here Re is the flow velocity U non-dimensionalized by the pipe diameter L and the kinematic viscosity ν. Beyond Re ≃ 2300 the turbulent regions start to grow in size. Eventually, they can fill macroscopic portions of the pipe. The resulting turbulent regions are called slugs. Recent experiments and simulations have provided a wealth of data on the life-time of puffs [1], and the structure and growth of slugs [2].

In order to contribute to understanding the nature of the transition from puffs to slugs, we constructed a coupled-map lattice where laminar flow is mimicked by a fixed point of the on-site dynamics, and turbulence amounts to long-lived chaotic structures that propagate through the lattice. In this model the transitions from puffs to slugs is related to an intermittency crisis of the dynamics. Implications for the interpretation of pipe-flow data will be given.
[1] B. Hof, et al, Phys Rev Lett 101 (2008) 214501.
[2] D. Moxey and D. Barkley, PNAS 107 (2010) 8091.