Thermal Convection in Rotating Spherical Shells: an Experimental and Numerical Approach within GeoFlow
- Paper number
IAC-06-A2.2.05
- Author
Mrs. Birgit Futterer, Brandenburg University of Technology Cottbus, Germany
- Coauthor
Dr. Marcus Gellert, Germany
- Coauthor
Mr. Thomas von Larcher, Germany
- Coauthor
Mr. Christoph Egbers, Germany
- Coauthor
Mr. Michael Huschto, Germany
- Year
2006
- Abstract
Thermal convection in spherical shells is an important model in fluid dynamics and geophysics. Research on natural convective instabilities influenced by an axial force field are of basic interest especially for the understanding of symmetry-breaking bifurcations during transitions to chaos. Thermal convective instabilities with simulated central force field provide details for understanding large scale geophysical motions as the convective transport phenomena in the Earth’s liquid outer core.
The presented work summarizes numerical, theoretical and experimental preliminary studies for an experiment on thermal convection in rotating spherical shells influenced by a central force field. This experiment will take place at the International Space Station in the European Columbus Modul inside the Fluid Science Laboratory (FSL). The special experiment container is called GeoFlow. The central force field is produced using the effect of an dielectrophoretic force field by impressing a high voltage on the inner and outer spheres. Hence flow visualisation has to go without tracers. Optical measurement methods as Wollaston shearing interferometry and schlieren technique will be used to determine the temperature fields and flow patterns.
Numerical and theoretical studies of spherical Rayleigh-Benard problem under a central dielectrophoretic force in microgravity environment are accomplished for a wide range of radius ratio, Prandtl, Rayleigh and Taylor number.
For testing the FSL environment and GeoFlow framework a laboratory experiment is designed and constructed including set-up of optical measurement techniques. In principle it has the same proportion as the original GeoFlow experiment. The Wollaston shearing interferometry detects the temperature dependency of refraction index producing an interferogram. A temperature gradient and thus a gradient of refraction index results into an optical path length difference for adjacent rays beaming through the spherical gap. The analysis of interferograms then gives an approximation of the temperature gradient of the flow field integrated in radial direction. To overcome difficulties in image processing of measured interferogram images, interferograms using numerical simulation data are constructed and compared to the experimentally obtained images.
- Abstract document
- Manuscript document
IAC-06-A2.2.05.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.