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Convection under rotation for Prandtl numbers near 1: Linear stability, wave-number selection, and pattern dynamics
 

Summary: Convection under rotation for Prandtl numbers near 1:
Linear stability, wave-number selection, and pattern dynamics
Yuchou Hu,1,2
Robert E. Ecke,1
and Guenter Ahlers2
1
Condensed-Matter and Thermal Physics Group, Center for Nonlinear Studies, Los Alamos National Laboratory,
Los Alamos, New Mexico 87545
2
Department of Physics and Center for Nonlinear Sciences, University of California, Santa Barbara, California 93106
Received 4 December 1996
Rayleigh-BeŽnard convection with rotation about a vertical axis was studied with the shadowgraph imaging
method up to a dimensionless rotation rate of 22. Most of the results are for a cylindrical convection cell
with a radius-to-height ratio 40 that contained CO2 at 33.1 bars with a Prandtl number 0.93. Measure-
ments of the critical Rayleigh number Rc and wave number kc for 0 22 agree well with predictions based
on linear stability analysis. Above onset and with rotation, the average wave number and details of the pattern
dynamics were studied. For 5, the initial onset was to a pattern of straight or slightly curved rolls. For
0.1 T/ Tc 1 0.5 but below the onset of spiral-defect chaos, rotation with 8 produced weak
perturbations of nonrotating patterns. Typically, this gave an ``S-shaped'' distortion of the zero-rotation pattern
of straight or somewhat curved rolls. Rotation had a stronger effect on the source and motions of dislocation

  

Source: Ahlers, Guenter - Department of Physics, University of California at Santa Barbara

 

Collections: Physics