 
Summary: Effect of the centrifugal force on domain chaos in RayleighBénard convection
Nathan Becker,1,
* J. D. Scheel,2,
M. C. Cross,2,
and Guenter Ahlers1,§
1
Department of Physics and iQCD, University of California, Santa Barbara, California 93106, USA
2
Department of Physics, California Institute of Technology 11436, Pasadena, California 91125, USA
Received 14 November 2005; published 23 June 2006
Experiments and simulations from a variety of sample sizes indicated that the centrifugal force significantly
affects the domainchaos state observed in rotating RayleighBénard convectionpatterns. In a largeaspect
ratio sample, we observed a hybrid state consisting of domain chaos close to the sample center, surrounded by
an annulus of nearly stationary nearly radial rolls populated by occasional defects reminiscent of undulation
chaos. Although the Coriolis force is responsible for domain chaos, by comparing experiment and simulation
we show that the centrifugal force is responsible for the radial rolls. Furthermore, simulations of the Bouss
inesq equations for smaller aspect ratios neglecting the centrifugal force yielded a domain precession
frequency f with 1 as predicted by the amplitudeequation model for domain chaos, but contradicted
by previous experiment. Additionally the simulations gave a domain size that was larger than in the experi
ment. When the centrifugal force was included in the simulation, and the domain size were consistent with
