期刊
ACTA ASTRONAUTICA
卷 66, 期 1-2, 页码 193-200出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actaastro.2009.05.027
关键词
Thermal convection; Spherical shell; Geophysical fluid dynamics; International Space Station (ISS); European module COLUMBUS; Fluid Science Laboratory (FSL)
资金
- ESA [AO-99049]
- German Aerospace Center DLR [50 WM 0122, 50 WM 0822]
Physical mechanisms of thermally driven rotating fluids are important for a large number of geophysical problems, e.g. to explain the convection of the Earth's liquid outer core. Objective of the 'GeoFlow' experiment is to study stability, pattern formation, and transition to chaos of thermal convection in fluid-filled concentric, co-axially rotating spheres. This experiment is integrated in the Fluid Science Laboratory of the European COLUMBUS module on International Space Station. Fluid dynamics of the experiment was predicted with numerical simulations by means of a spectral code. In the non-rotating case the onset of convection bifurcated into steady fluid now. Here patterns of convection showed co-existing states with axisymmetric, cubic and pentagonal modes. Transition to chaos was in the form of sudden onset. For the thermal convection in rotating spheres the onset of first instability showed an increase of modes for higher parameter regime. Transition was from steady via periodic to chaotic behaviour. Convection patterns of the experiment are observed with the Wollaston shearing interferometry. Images are in terms of interferograms with fringe patterns corresponding to special convective flows. A first glance at the images showed the classification of sub- and supercritical flow regimes. Aligned with numerical data a shift between experiment and numerical simulation was identified. Identification of convection patterns in interferograms was demonstrated for the example of a supercritical flow. (C) 2009 Elsevier Ltd. All rights reserved.
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