Transition to turbulence and turbulent bifurcation in a von Karman flow

Add to your list(s) Download to your calendar using vCal

• Daviaud, F (CEA/Saclay)
• Thursday 11 September 2008, 10:40-11:00
• Seminar Room 1, Newton Institute.

If you have a question about this talk, please contact Mustapha Amrani.

The Nature of High Reynolds Number Turbulence

We study the transition from laminar flow to fully developed turbulence in a von Karman flow (Re from 50 to 106). The flow undergoes a classical succession of bifurcations driven by the destabilization of the azimuthal shear-layer. We observe that the transition to turbulence is globally supercritical: the kinetic energy of the velocity fluctuations can be used as a single order parameter to characterize the transition. We also measure the dissipation through the torque injected in the flow. For high Reynolds numbers, the mean flow presents multiple solutions: the canonical symmetric solution becomes marginally unstable towards a flow which breaks the basic Rπ-symmetry. The global bifurcation between these states is highly subcritical and the system thus keeps a memory of its history. The transition recalls low-dimension dynamical system transitions and exhibits slow dynamics and peculiar statistics.

References F. Ravelet et al., J. Fluid Mech. 601, 339 (2008) F. Ravelet et al., Phys. Rev. Lett. 93, 164501 (2004)

This talk is part of the Isaac Newton Institute Seminar Series series.

This talk is included in these lists:

• All CMS events
• Featured lists
• INI info aggregator
• Isaac Newton Institute Seminar Series
• School of Physical Sciences
• Seminar Room 1, Newton Institute
• bld31

Note that ex-directory lists are not shown.