Journal of Fluid Mechanics

Instabilities of convection rolls in a fluid of moderate Prandtl number

F. H.  Busse a1 and R. M.  Clever a1
a1 Institute of Geophysics and Planetary Physics, University of California, Los Angeles

Article author query
busse fh   [Google Scholar] 
clever rm   [Google Scholar] 


The instabilities of two-dimensional convection rolls in a horizontal fluid layer heated from below are investigated in the case when the Prandtl number is seven or lower. Two new mechanisms of instability are described theoretically as well as experimentally. The knot instability causes the transition to spoke-pattern convection at higher Rayleigh numbers while the skewed varicose instability accomplishes a change to larger horizontal wavelengths of the convection rolls. Both instabilities disappear in the limits of small and large Prandtl number. Although the experimental methods fail in realizing closely the infinitely conducting boundaries assumed in the theory, the observations agree in all qualitative aspects with the theoretical predictions.

(Published Online April 19 2006)
(Received January 3 1978)