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Gyroflow
A rotating platform for geophysical fluid dynamics


French version

Members: A. Campagne, N. Machicoane, P.-P. Cortet, B. Gallet, F. Moisy

Previous members: J. Boisson, C. Lamriben, M. Rabaud

Collaborations : L.R.M. Maas (NIOZ, Univ. Utrecht), B. Voisin (LEGI, Grenoble), D. Cébron (ETH Zurich), P. Billant et J.-M. Chomaz (LadHyX), T. Dauxois et G. Bordes (ENS Lyon).



What is Gyroflow?

Gyroflow is a rotating platform designed for research in geophysical fluid dynamics.

This platform, 2 m in diameter, can rotate up to 1 ton of experiment and instruments, at a maximum angular velocity of 30 rpm.

It is installed in the laboratory FAST (Fluides, Automatique et Systèmes Thermiques), in Orsay (France), since september 2009.


The Gyroflow platform. Particle Image Velocimetry measurements are performed using the camera (right, in blue), and the pulsed laser (left, in black).



What is a geophysical flow?

Geophysical flows are flows dominated by the effects of rotation (through the Coriolis force) and stratification (through the buoyancy force due to a density gradient).

Large scale ocean currents and atmospheric circulations provide illustrations of the remarkable features of geophysical flows: quasi-two-dimensionality and the presence of large scale coherent vortices.

Geophysical flows are also present in gaseous planets - e.g., Jupiter's red spot -, in stars, or in the liquid cores of planets.


Two examples of geophysical flows: two cyclones in the South of Island, and the great red spot of Jupiter (source: NASA).



What is the effect of the Coriolis force on a flow

The Coriolis force deflects the trajectory of fluid particles, in a way similar to the effect of a magnetic field on charged particles. In an incompressible fluid, the resulting circular trajectory gives rise to an anisotropic propagative wave, called an inertial wave.

In the limit of large rotation rates, this inertial wave reduces to a column of fluid parallel to the rotation axis (Taylor-Proudman column), in which the flow is purely two-dimensional.

When the flow is turbulent, the effect of the Coriolis force is subtle: large scales may be dominated by the rotation, whereas small scales are not, because of their fast dynamics compared to the rotation rate. As a consequence, the large scales can be described as a system of superimposed inertial waves, leading to a partial two-dimensionalization of turbulence.


Rotating turbulence experiments

A series of experiments have been carried out to investigate the influence of the Coriolis force on turbulence. Two experimental configurations have been set up:

  • A decaying turbulence experiment, in which turbulence is generated by the rapid translation of a grid in the fluid
  • A forced turbulence experiment, in which vortex dipole generators continuously inject energy in the center of the flow.


Grid-generated decaying turbulence experiment on the rotating platform (october 2009).



Forced turbulence experiment, in which vortex dipole generators continuously inject energy in the center of the flow (february 2013).


Acknowledgments

The project Gyroflow has been funded by RTRA "Triangle de la Physique" (projects 2008-080T and 2011-037T) and Agence Nationale de la Recherche (projects 6-BLAN-0363-01 "HiSpeedPIV" and 2011-BS04-006-01 "ONLITUR").



Support from laboratoire FAST (Université Paris-Sud, Université Pierre et Marie Curie, CNRS), and laboratoire SPHYNX from CEA / SPEC, is also acknowledged.



The forced turbulence experiments have been carried out in collaboration with P. Augier, P. Billant, J.-M. Chomaz and A. Garcia (Laboratoire LadHyX, Ecole Polytechnique).


Large audience papers

  • A liquid Foucault pendulum, CNRS international magazine, 27 (october 2012).
  • Un pendule de Foucault version liquide, CNRS Le journal, 268 (september-october 2012).
  • Un pendule de Foucault fluide
    J. Boisson, D. Cébron, F. Moisy, P.-P. Cortet, Reflets de la Physique 31 22-23 (2012).
    [Abstract | PDF]
  • Et pourtant elle tourne...
    F. Moisy, C. Lamriben, P.-P. Cortet, M. Rabaud, Plein Sud Spécial Recherche 2010-2011, 28-37 (2011).
    [PDF]

Read more


Publications

The following papers are based on data obtained from the platform Gyroflow.

  • Two-dimensionalization of the flow driven by a slowly rotating impeller in a rapidly rotating fluid
    N. Machicoane, F. Moisy and P.-P. Cortet, Phys. Rev. Fluids 1, 073701 (2016)
    [Abstract | PDF]
  • Turbulent drag in a rotating frame
    A. Campagne, N. Machicoane, B. Gallet, P.-P. Cortet and F. Moisy, J. Fluid Mech. 794, R5 (2016)
    [Abstract | PDF]
  • Influence of the multipole order of the source on the decay of an inertial wave beam in a rotating fluid
    N. Machicoane, P.-P. Cortet, B. Voisin, and F. Moisy, Phys. Fluids 27, 066602 (2015)
    [Abstract | PDF]
  • Disentangling inertial waves from eddy turbulence in a forced rotating turbulence experiment
    A. Campagne, B. Gallet, F. Moisy and P.-P. Cortet, Phys. Rev. E 91, 043016 (2015)
  • [Abstract | PDF]
  • Structure and dynamics of rotating turbulence: a review of recent experimental and numerical results
    F.S. Godeferd and F. Moisy, Applied Mechanics Reviews 67, 030802 (2015)
    [Abstract | PDF]
  • Scale-dependent cyclone-anticyclone asymmetry in a forced rotating turbulence experiment
    B. Gallet, A. Campagne, P.-P. Cortet and F. Moisy, Phys. Fluids 26 035108 (2014).
    [Abstract | PDF]
  • Direct and inverse energy cascades in a forced rotating turbulence experiment
    A. Campagne, B. Gallet, F. Moisy and P.-P. Cortet, Phys. Fluids 26, 125112 (2014)
    [Abstract | PDF]
  • Inertial waves and modes excited by the libration of a rotating cube
    J. Boisson, C. Lamriben, L.R.M. Maas, P.-P. Cortet, F. Moisy, Phys. Fluids 24, 076602 (2012).
    [Abstract | PDF | movies]
  • Earth rotation prevents exact solid body rotation of fluids in the laboratory
    J. Boisson, D. Cébron, F. Moisy, P.-P. Cortet, EPL 98, 59002 (2012).
    [Abstract | PDF]
  • Experimental evidence of a triadic resonance of plane inertial waves in a rotating fluid
    G. Bordes, F. Moisy, T. Dauxois, P.-P. Cortet, Phys. Fluids 24, 014105 (2012).
    [Abstract | PDF]
  • Direct measurements of anisotropic energy transfers in a rotating turbulence experiment
    C. Lamriben, P.-P. Cortet, F. Moisy, Phys. Rev. Lett. 107, 024503 (2011).
    [Abstract | PDF]
  • Excitation of inertial modes in a closed grid turbulence experiment under rotation
    C. Lamriben, P.-P. Cortet, F. Moisy, L. Maas, Phys. Fluids 23, 015102 (2011).
    [Abstract | PDF]
  • Viscous spreading of an inertial wave beam in a rotating fluid
    P.-P. Cortet, C. Lamriben, F. Moisy, Phys. Fluids 22, 086603 (2010).
    [Abstract | PDF]