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Magnetically Induced Rotating Rayleigh-Taylor Instability
Published on: March 3, 2017
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Shortcut to Geostrophy in Wave-Driven Rotating Turbulence: The Quartetic Instability.
Maxime Brunet1, Basile Gallet2, Pierre-Philippe Cortet1
1Université Paris-Saclay, CNRS, FAST, 91405 Orsay, France.
Physical Review Letters
|April 14, 2020
Summary
Experiments show that while moderate wave forcing creates subharmonic waves, stronger forcing unexpectedly generates geostrophic flow. This transition to geostrophy is driven by a novel "quartetic instability" in rotating turbulence.
Area of Science:
- Fluid dynamics
- Geophysics
- Wave turbulence
Background:
- Rotating turbulence is crucial in geophysical flows.
- Understanding energy transfer mechanisms in rotating systems is key.
- Inertial waves are fundamental to rotating fluid dynamics.
Purpose of the Study:
- Investigate energy transfer in wave-driven rotating turbulence.
- Explore the transition from inertial wave dynamics to geostrophic flow.
- Identify the instability mechanisms responsible for geostrophy emergence.
Main Methods:
- Laboratory experiments using a rotating platform and wave makers.
- Controlled generation of inertial wave beams.
- Analysis of nonlinear wave interactions and energy transfer.
Main Results:
- Moderate forcing leads to subharmonic wave generation via triadic resonance.
- Stronger forcing results in kinetic energy condensation into unforced geostrophic flow.
- A novel 'quartetic instability' is identified as the trigger for geostrophy.
Conclusions:
- The study reveals a new pathway to geostrophy in rotating fluids.
- Quartetic instability acts as a secondary instability to triadic resonance.
- Experimental findings challenge existing weak turbulence theories in this regime.
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