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Coriolis platform

The Coriolis platform at LEGI Grenoble
CNRS
Joel Sommeria

Equipe Coriolis/LEGI
21 avenue des Martyrs
38 000 Grenoble
France
http://www.legi.grenoble-inp.fr/web/

Diameter of 13 m and height of 8 m. For experimental modelling of oceanic or atmospheric flows, with or without density stratification or topography. Dealine proposals: Dec. 18, 2010

Description of facility:

Technical data

Main features
Platform diameter 14 m
Tank diameter 13 m
Maximum water height 1 m
Weight of the empty tank 150 tons
Maximum charge 180 tons
Rotation speed 0-2 turns/min
Precision
Rotation speed 10-4
Verticality 3.10-6
Web site : Coriolis Platform

 

The « Coriolis » rotating platform, 14 m in diameter, is the largest turntable in the world. Its total weight is 150 tons and it supports an extra load of 180 tons. The axis of rotation is vertical with an accuracy ± 3.10-6 rad. Its rotation period can be set with high stability (dT/T = 10-4) between 30 and 1000 s and can be modulated by computer control in order to generate permanent or oscillating circular flows, so to simulate tidal effects for instance.

The platform is equipped with a tank of 13 m diameter and 1.2 m height. It can be filled with homogeneous or density stratified water with any vertical profile (e.g. multilayer or linear). The stratification is made by filling the tank through the bottom with increasingly salty water, obtained by computer controlled mixing from two underground tanks with specified salinity and temperature (within 1C). Various fixed or moving obstacles can be installed in the tank (transverse channel 10 m long and 4 m wide, annular shelf, oscillating plates, towed cylinder, cylindrical plunger …). All the instruments, including lasers and computers, stay on the platform, where electricity, water and computer network are available, like in an ordinary laboratory. Researchers can stay on the platform during rotation. Many operations are then easier than in a small rotating tank.

Thanks to the large dimensions, large Reynolds number (inertia/viscous friction) can be reached, and Rossby numbers (inertia/rotation) as low as 10-3 -10-2, like in natural geophysical or environmental flows. This is obtained with negligible centrifugal effects, e.g. small curvature of isopycnals.

The facility is equipped with continuous Argon laser ( 8 W) and Yag solid laser, and use highly transparent water for illumination along a large scale laser sheet. Particle Imaging Velocimetry (PIV) systems provide time resolved velocity fields in both horizontal and vertical planes of up to 3 m x 4 m in size, with a relative precision 2%. The laser sheet position is scanned by a computer controlled system, so that image correlation for PIV can be made in a volume. Both vorticity and divergence fields can be computed from the PIV data and directly compared with numerical computations.

Various techniques of flow visualization are available, with dye, hydrogen bubbles or tin oxyde electrolytically released from a wire. Illumination devices and high quality video cameras are available. Tracking of float motion by image processing is available to record lagrangian trajectories in a plane.

A wide variety of local probes is also available, including ultrasonic and laser Doppler velocimeters, salinity and temperature sensors.

  1. Capacitive probes of free surface displacement with a precision 0.01 mm.
  2. Ultrasonic probes for height displacement of salinity interface, with a precision 0.3 mm.
  3. Ultrasonic probes for measuring density profiles at up to fifteen locations simultaneously.
  4. Ultrasonic velocimeters (9 channels) with a precision 0.1 mm/s for velocities in the range 0-20 cm/s.
  5. Conductivity probes for measuring time series of local density fluctuations and high resolution density profiles.

Probe displacements and data acquisition are controlled by computer. Tools for data processing and analyses are available.


Cyclone formation
Uploaded by coriolis-legi
  Here is an example of a scientific project using several aspects of the Coriolis platform facility :
- Design of a prototype cyclone generator by the engineers of the Coriolis platform
- On demand stratification (linear) and rotation period (120s)
- Flow visualisation using Light Induced Fluorescence
- Velocity measurements using Particule Image Velocimetry
- Vertical scans to explore the 3D structure of the cyclone

 

Project Reports using this facility Proceedings based on experiments using this facility
Laboratory Simulation of Western Boundary Currents Over Shelf Topography and of Their Extensions Laboratory simulation of western boundary currents over shelf topography and of their extensions
Nonlinear transfer of internal-tide energy and the effect of rotation: an experimental study on bottom reflection, subharmonic resonance, and scattering at a thermocline. Nonlinear transfer of internal-tide energy and the effect of rotation: an experimental study on bottom reflection, subharmonic resonance, and scattering at a thermocline
Modelling Antarctic Flows Modelling antarctic flows
Effect of rotation on massively separated turbulent flow Effects of rotation on turbulent channel flows
Characterising ‘Zonostrophic flow’ in b-plane Geostrophic Turbulence Eddy-driven jets and vortices in convectively forced geostrophic turbulence on a topographic beta-plane
Island wakes Vortex assymetry in island wakes
Generation of interfacial solitons by internal-wave beams Generation of interfacial solitons by internal-wave beams
Planetary waves over a linearly sloping bottom with rotation Laboratory experiments and a non-harmonic theory for topographic rossby waves
Effect of rotation on internal solitary waves Effect of rotation on internal solitary waves
Evolution of coherent modes in the dynamics of planetary polar vortices Barotropic instability of planetary polar vortices: civ analysis of specific multi-lobed structures
Experiments on vertical motions of rotating flows over variable topography Experiments on vertical motions of rotating flows over variable topography

 

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