Berlin 2015 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 26: Focus Session: Percolation and turbulent transition

DY 26.4: Talk

Wednesday, March 18, 2015, 10:45–11:00, BH-N 243

Critical exponents for the onset of turbulence in Couette flow — Liang Shi and •Björn Hof — IST Austria, Klosterneuburg, Austria

At onset turbulence appears in localized patches surrounded by laminar flow. While individual spots eventually decay, they can also seed new ones in their neighbourhood. As the Reynolds number is increased turbulence becomes sustained once the rate of spot generation outweighs the decay rate of spots. In direct numerical simulations of Couette flow we determine the resulting turbulent fractions and size distributions close to this critical point. The exponents describing the scaling of the turbulent fraction, as well as those for correlation length and correlation times at critical are in excellent agreement with directed percolation.