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15 mins
Braid Entropy of Faraday Waves driven 2D Turbulence
Nicolas FRANCOIS, Hua Xia, Horst Punzmann, Michael Shats
Session: Lagrangian aspects of turbulence 4
Session starts: Friday 28 August, 10:30
Presentation starts: 11:15
Room: Room F

Nicolas FRANCOIS (The Australian National University)
Hua Xia (The Australian National University)
Horst Punzmann (The Australian National University)
Michael Shats (The Australian National University)

We report new experimental results that use tools from braid theory to characterize two-dimensional turbulent flows driven by Faraday waves. The average topological length of the material fluid lines is found to grow exponentially with time. It allows us to compute the braid’s topological entropy SBraid. We show that SBraid increases as the square root of the turbulence kinetic energy E ~ u^2, where u^2 is the horizontal velocity variance . At long times, the PDFs of Lbraid are positively skewed and present strong exponential tails.