Pattern Formation in Rayleigh-Bénard Convection at Small Prandtl Numbers and with Rotation About a Vertical Axis

Tuesday, May 12, 1998 - 2:30pm - 3:00pm
Keller 3-180
Guenter Ahlers (University of California)
This talk will discuss results from and future prospects for experimental studies of Rayleigh-Bénard convection with rotation about a vertical axis. At dimensionless rotation rates 0 $leq$ $Omega$ $leq$ 20 and for Prandtl numbers $sigma$ simeq 1, measurements of Küppers-Lortz-unstable patterns have offered a unique opportunity to study spatio-temporal chaos immediately above a supercritical bifurcation. However, for $Omega$ > 70 and $sigma$ simeq 1 patterns were found to be cellular near onset with local four-fold coordination. They differ from the theoretically expected Küppers-Lortz-unstable state. Stable as well as intermittent defect-free rotating square lattices exist in this parameter range.

Smaller Prandtl numbers ( 0.16