Convection experiments in a centrifuge and the generation of plumes in a very viscous fluid
Abstract
In this paper, experiments are described for which inertial effects are negligible. A small aspectratio tank filled with a very viscous fluid (Pr = 10 to the 6th) is used to observe the behavior of convection for Rayleigh numbers up to 6.3 x 10 to the 5th. These high values are reached by conducting the experiment in a centrifuge which provides a 130fold increase in apparent gravity. Rotational effects are small, but cannot be totally dismissed. In this geometry, thermal boundary layer instabilities are indeed observed, and are found to be very similar to their lower Prandtl number counterparts. It is tentatively concluded that once given a certain degree of 'vulnerability' convection can develop 'plume' like instabilities, even when the Prandtl number is infinite. The concept is applied to the earth's mantle and it is speculated that 'plumes' could well be the dominant mode of smallscale convection under the lithospheric plates.
 Publication:

Annales Geophysicae
 Pub Date:
 June 1984
 Bibcode:
 1984AnGeo...2..303N
 Keywords:

 Centrifuges;
 Convection Currents;
 Earth Mantle;
 Geodynamics;
 Plumes;
 Viscous Fluids;
 Boundary Layer Stability;
 Interferometry;
 Lithosphere;
 Prandtl Number;
 Rayleigh Number;
 Thermal Boundary Layer;
 Fluid Mechanics and Heat Transfer, Earth Science