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DY: Fachverband Dynamik und Statistische Physik

DY 16: Focus: Fundamental aspects of turbulent convection

DY 16.11: Vortrag

Dienstag, 21. März 2017, 12:45–13:00, ZEU 118

Nonlinear mode decomposition of reversal dynamics in Rayleigh-Bénard convection — •Oliver Kamps¹ and Tim Kroll² — ¹Center for Nonlinear Science, WWU Münster, Germany — ²Institut für Theoretische Physik, WWU Münster, Germany

Complex systems composed of a large number of degrees of freedom can often be described on the macroscopic level by only a few interacting modes or coherent structures. A paradigmatic example for this behaviour is Rayleigh-Bénard convection. In general many turbulent flows seem to be composed of a few coherent structures and it might be possible to find a low dimensional representation of the flow. This has to be done in most cases by means of data analysis methods since it is not possible to derive the low dimensional model from the basic equations of the complex system.

Based on ideas developed in [1,2] we present a nonlinear decomposition method that is able to extract coherent structures and their dynamics from data of turbulent flow fields. We apply this method to reversal dynamics in Rayleigh-Bénard convection in order to derive a low dimensional representation of the system. We also show the relation to other decomposition methods like dynamic mode decomposition.
[1] C. Uhl, R. Friedrich, and H. Haken, Zeitschrift für Physik B, 92, 1993
[2] F. Kwasniok, Physica D: Nonlinear Phenomena, 92, 1996