Flow structure in a Rayleigh-Benard cell upon impulsive spin-up
We investigate convection in a cylindrical Rayleigh-Benard cell with radius-to-height ratio {Gamma} = {1/2}. The cell is subjected to impulsive spin-up about its vertical axis. We use TLC (thermochromic liquid crystal) for temperature field measurements and PIV (particle image velocimetry) for the velocity reconstruction of the transition in the range of Rayleigh numbers R from 5 x 10{sup 7} to 5 x 10{sup 8} and Taylor numbers Ta from 0 up to 2.4 x 10{sup 10}. The initial (at rest) and the final (in steady rotation) vection. The most persistent transient feature emerging is a sharply defined ringlike pattern or concentric patterns characterized by a decrease in temperature, axial velocity directed downward and high azimuthal shear. The latter leads to formation of an azimuthally regular structure of Kelvin-Helmholz vortices. During the next stage of the transition, the vortical structure loses azimuthal regularity and the pattern characteristic of turbulent rotating convection forms.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Human Resources and Administration, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 554159
- Report Number(s):
- LA-UR--97-2949; CONF-971157--; ON: DE98001075
- Country of Publication:
- United States
- Language:
- English
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