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Large-scale geophysical flows on a table top
1Nonlinear Science Laboratory, Department of Physics, University of New Orleans, New Orleans, Lousiana 70148, USA. jhegseth@uno.edu
Annals of the New York Academy of Sciences
|November 26, 2002
Summary
Laboratory experiments explored fluid convection in spherical geometry using two buoyancy forces. Researchers observed instabilities leading to upward-traveling rolls under specific conditions, simulating geophysical phenomena.
Area of Science:
- Geophysics
- Fluid Dynamics
- Laboratory Simulations
Background:
- Geophysical systems often involve complex fluid dynamics under varying buoyancy forces.
- Spherical geometry is crucial for modeling planetary interiors and atmospheres.
- Understanding convection is key to explaining phenomena like planetary magnetic fields.
Purpose of the Study:
- To create laboratory geophysical analogs in spherical geometry.
- To investigate fluid convection driven by dual buoyancy forces (thermal and electric).
- To analyze the instability of convection flows and the formation of organized structures.
Main Methods:
- Utilized two experimental systems with concentric spheres.
- Employed real-time holographic interferometry and shadowgraph visualization.
- Applied thermal gradients (DeltaT) and AC voltage differences (DeltaV) to induce buoyancy.
Main Results:
- Normal gravitational buoyancy consistently produced axisymmetric convection cells.
- Sufficiently large DeltaT and DeltaV induced instabilities, forming toroidal or spiral rolls.
- These rolls initiated near the inner sphere's equator and propagated upward.
Conclusions:
- Dual buoyancy forces can lead to complex flow instabilities in spherical systems.
- Observed roll formations provide insights into geophysical fluid dynamics.
- The study demonstrates the feasibility of simulating geophysical phenomena in controlled laboratory settings.