title: Scale invariance at the onset of turbulence in Couette flow.
abstract: Laminar-turbulent intermittency is intrinsic to the transitional regime of a wide range of fluid flows including pipe, channel, boundary layer, and Couette flow. In the latter turbulent spots can grow and form continuous stripes, yet in the stripe-normal direction they remain interspersed by laminar fluid. We carry out direct numerical simulations in a long narrow domain and observe that individual turbulent stripes are transient. In agreement with recent observations in pipe flow, we find that turbulence becomes sustained at a distinct critical point once the spatial proliferation outweighs the inherent decaying process. By resolving the asymptotic size distributions close to criticality we can for the first time demonstrate scale invariance at the onset of turbulence.
authors.affiliation: Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany and Institute of Geophysics, University of Göttingen, 37077 Göttingen, Germany.
authors.forename: Liang
authors.initials: L
authors.lastname: Shi
authors.affiliation: Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany and Institute of Fluid Mechanics, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Avila
authors.affiliation: Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany and Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria.
authors.forename: Björn
authors.initials: B
authors.lastname: Hof