Journal Article10.1017/S0022112074000061
Oscillatory and collective instabilities in large Prandtl number convection
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TL;DR: In this paper, an experimental study of transitions from steady bimodal convection to time-dependent forms of convection is described, and two mechanisms of instability can be separated from the effects of random noise.
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Abstract: An experimental study of transitions from steady bimodal convection to time-dependent forms of convection is described. Using controlled initial conditions for the onset of bimodal convection two mechanisms of instability can be separated from the effects of random noise. The oscillatory instability of bimodal cells introduces standing waves closely resembling those occurring in low Prandtl number convection. The collective instability introduces spoke-pattern convection which is characteristic for turbulent large Prandtl number convection. Both instabilities originate primarily from the momentum advection terms in the equations of motion, as is evident from the strong Prandtl number dependence of the critical Rayleigh number Rt for the onset of oscillations. The results are discussed in relation to previous experiments and recent theoretical work.
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References
Some further studies on the transition to turbulent convection
TL;DR: In this article, the authors investigated the effect of curvature of the roll axis, forced by curved side walls, upon the second transition at RII and found that curvature leads to a lowering of RII.
287
Thermal convection in high prandtl number liquids at high rayleigh numbers
E.F.C Somerscales,I.W Gazda +1 more
TL;DR: In this paper, an experimental investigation was made of the temperature distribution in a heated horizontal layer of high Prandtl number (6 and 18) silicone fluids confined between rigid, parallel, conducting plates.
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Measurements on the Development of Thermal Turbulence in Air between Horizontal Plates
G. E. Willis,James W. Deardorff +1 more
TL;DR: In this article, the transition from steady to turbulent thermal convection in air between horizontal plates is inferred from temperature measurements, and spatial and temporal records of air temperature for Rayleigh numbers ranging from 5000 to 1.5 × 106 are presented along with spatial temperature spectra.
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