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Stability and resonant wave interactions of confined two-layer Rayleigh-Bénard systems
Published in Cambridge University Press
2014
Volume: 754
   
Pages: 415 - 455
Abstract
The current work analyses the onset characteristics of Rayleigh-Bénard convection in confined two-dimensional two-layer systems. Owing to the interfacial interactions and the possibilities of convection onset in the individual layers, the two-layer systems typically exhibit diverse excitation modes. While the attributes of these modes range from the non-oscillatory mechanical/thermal couplings to the oscillatory standing/travelling waves, their regimes of occurrence are determined by the numerous system parameters and property ratios. In this regard, the current work aims at characterising their respective influence via methodical linear and fully nonlinear analyses, carried out on fluid systems that have been selected using the concept of balanced contrasts. Consequently, the occurrence of oscillatory modes is found to be associated with certain favourable fluid combinations and interfacial heights. The further branching of oscillatory modes into standing and travelling waves seems to additionally rely on the aspect ratio of the confined cavity. Specifically, the modulated travelling waves have been observed to occur (amidst standing wave modes) at discrete aspect ratios for which the onset of oscillatory convection happens at unequal fluid heights. This behaviour corresponds to the typical m:n resonance where the critical wavenumbers of convection onset in the layers are dissimilar. Based on all of these observations, an attempt has been made in the present work to identify the oscillatory excitation modes with a reduced number of non-dimensional parameters. © 2014 Cambridge University Press.
About the journal
JournalData powered by TypesetJournal of Fluid Mechanics
PublisherData powered by TypesetCambridge University Press
ISSN00221120
Open AccessNo
Concepts (16)
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    Wave transmission
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    BUOYANCY DRIVEN INSTABILITY
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    CONVECTION IN CAVITIES
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    CONVECTION ONSETS
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    Interfacial interaction
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    Non-dimensional parameters
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    OSCILLATORY CONVECTION
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    STANDING WAVE MODES
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    Two-layer systems
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    Aspect ratio
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    Convection
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    Flow modeling
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    Flow stability
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    Oscillating flow
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    Rayleigh number
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    Wave-structure interaction