Heteroclinic behavior in rotating Rayleigh-Bénard convection

  • We investigate numerically the appearance of heteroclinic behavior in a three-dimensional, buoyancy-driven fluid layer with stress-free top and bottom boundaries, a square horizontal periodicity with a small aspect ratio, and rotation at low to moderate rates about a vertical axis. The Prandtl number is 6.8. If the rotation is not too slow, the skewed-varicose instability leads from stationary rolls to a stationary mixed-mode solution, which in turn loses stability to a heteroclinic cycle formed by unstable roll states and connections between them. The unstable eigenvectors of these roll states are also of the skewed-varicose or mixed-mode type and in some parameter regions skewed-varicose like shearing oscillations as well as square patterns are involved in the cycle. Always present weak noise leads to irregular horizontal translations of the convection pattern and makes the dynamics chaotic, which is verified by calculating Lyapunov exponents. In the nonrotating case, the primary rolls lose, depending on the aspect ratio, stability We investigate numerically the appearance of heteroclinic behavior in a three-dimensional, buoyancy-driven fluid layer with stress-free top and bottom boundaries, a square horizontal periodicity with a small aspect ratio, and rotation at low to moderate rates about a vertical axis. The Prandtl number is 6.8. If the rotation is not too slow, the skewed-varicose instability leads from stationary rolls to a stationary mixed-mode solution, which in turn loses stability to a heteroclinic cycle formed by unstable roll states and connections between them. The unstable eigenvectors of these roll states are also of the skewed-varicose or mixed-mode type and in some parameter regions skewed-varicose like shearing oscillations as well as square patterns are involved in the cycle. Always present weak noise leads to irregular horizontal translations of the convection pattern and makes the dynamics chaotic, which is verified by calculating Lyapunov exponents. In the nonrotating case, the primary rolls lose, depending on the aspect ratio, stability to traveling waves or a stationary square pattern. We also study the symmetries of the solutions at the intermittent fixed points in the heteroclinic cycle.show moreshow less

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Metadaten
Author:Ayhan Demircan, Stefan Scheel, Norbert Seehafer
URN:urn:nbn:de:kobv:517-opus-14914
Series (Serial Number):NLD Preprints (paper 055)
Document Type:Preprint
Language:English
Date of Publication (online):2007/08/15
Year of Completion:1999
Publishing Institution:Universität Potsdam
Release Date:2007/08/15
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie
Wissenschaftliche Einrichtungen / Interdisziplinäres Zentrum Dynamik komplexer Systeme
Extern / Extern
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
PACS Classification:40.00.00 ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS / 47.00.00 Fluid dynamics (for fluid dynamics of quantum fluids, see section 67; see also section 83 Rheology; for sound generation by fluid flow, see 43.28.Ra-in Acoustics Appendix) / 47.20.-k Flow instabilities (see also 47.15.Fe Stability of laminar flows) / 47.20.Bp Buoyancy-driven instabilities (e.g., Rayleigh-Benard)
40.00.00 ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS / 47.00.00 Fluid dynamics (for fluid dynamics of quantum fluids, see section 67; see also section 83 Rheology; for sound generation by fluid flow, see 43.28.Ra-in Acoustics Appendix) / 47.20.-k Flow instabilities (see also 47.15.Fe Stability of laminar flows) / 47.20.Ky Nonlinearity, bifurcation, and symmetry breaking
40.00.00 ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS / 47.00.00 Fluid dynamics (for fluid dynamics of quantum fluids, see section 67; see also section 83 Rheology; for sound generation by fluid flow, see 43.28.Ra-in Acoustics Appendix) / 47.32.-y Vortex dynamics; rotating fluids (for vortices in superfluid helium, see 67.25.dk and 67.30.he)