Optical observation of convective flow patterns in liquid helium

Woodcraft, A.; Lucas, P.; Matley, Richard G.; Wong, W. Y. T.

doi:10.1007/bf02569458

Cited by 5 publications

(4 citation statements)

References 4 publications

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“…1 and 10-12͒ and partly to make predictions for future experiments now that flow visualization at cryogenic temperatures has become possible. 13 We have also used smaller domains in order to reduce the length of the immensely long transients encountered in our simulations of water-ethanol mixtures. 8 As a result we have been able to explore a larger range of values of the Rayleigh number, reaching values at which the low-dimensional description of this system valid near threshold begins to breakdown.…”

Section: Discussionmentioning

confidence: 99%

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Simulations of oscillatory convection in He3–He4 mixtures in moderate aspect ratio containers

Batiste¹,

Knobloch²

2005

Physics of Fluids

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Simulations of 3 He-4 He mixtures with negative separation ratios in two-dimensional containers with realistic boundary conditions and moderately large aspect ratio ⌫ are described. The system exhibits a large variety of states with complex time dependence including intermittent wave localization and chaotic "repeated transients." Steady but localized states are also found. Particular attention is paid to the transitions that occur for ͑R − R c ͒ / R c Ϸ ⌫ −2 , where R is the Rayleigh number and R c its critical value for the primary instability, in order to clarify the gradual transition from a small number of active degrees of freedom ͓͑R − R c ͒ / R c Ӷ⌫ −2 ͔ to many active degrees of freedom ͓͑R − R c ͒ / R c ӷ⌫ −2 ͔.

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Section: Discussionmentioning

confidence: 99%

“…[2][3][4] Of these the latter readily permit flow visualization, a fact invaluable for the interpretation of all measurements. However, the recent development of visualization techniques at cryogenic temperatures 13 offers the possibility that comparable experiments can now be performed on 3 He- 4 He mixtures.…”

Section: Introductionmentioning

confidence: 99%

Simulations of oscillatory convection in He3–He4 mixtures in moderate aspect ratio containers

Batiste¹,

Knobloch²

2005

Physics of Fluids

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“…Binary-fluid convection offers perhaps the best opportunity for studying states of this type in a laboratory. However, despite progress in visualization at cryogenic temperatures (Woodcraft et al 1999) water-ethanol mixtures provide the most convenient system for such studies. Consequently we focus here on the properties of convectons in water-ethanol mixtures, and use experimentally accessible parameters and boundary conditions to study their properties.…”

Section: Introductionmentioning

confidence: 99%

Spatially localized binary-fluid convection

et al. 2006

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Multiple states of spatially localized steady convection are found in numerical simulations of water-ethanol mixtures in two dimensions. Realistic boundary conditions at the top and bottom are used, with periodic boundary conditions in the horizontal. The states form by a mechanism similar to the pinning region around a Maxwell point in variational systems, but are located in a parameter regime in which the conduction state is overstable. Despite this the localized states can be stable. The properties of the localized states are described in detail, and the mechanism of their destruction with increasing or decreasing Rayleigh number is elucidated. When the Rayleigh number becomes too large the fronts bounding the state at either end unpin and move apart, allowing steady convection to invade the domain. In contrast, when the Rayleigh number is too small the fronts move inwards, and eliminate the localized state which decays into dispersive chaos. Out of this state spatially localized states re-emerge at irregular times before decaying again. Thus an interval of Rayleigh numbers exists that is characterized by relaxation oscillations between localized convection and dispersive chaos.

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“…The first studies into the topic have probably emerged in the field of binary-fluid convection, where spatially localised convection rolls have been observed in water-ethanol mixtures [9] or helium [10]. There localised convection domains of arbitrary length are found to be stable, being surrounded by the conductive state.…”

Section: Introductionmentioning

confidence: 99%

Snaking bifurcations in a self-excited oscillator chain with cyclic symmetry

Papangelo

Grolet

Salles

et al. 2017

Communications in Nonlinear Science and Numerical Simulation

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Snaking bifurcations in a chain of mechanical oscillators are studied. The individual oscillators are weakly nonlinear and subject to self-excitation and subcritical Hopf-bifurcations with some parameter ranges yielding bistability. When the oscillators are coupled to their neighbours, snaking bifurcations result, corresponding to localised vibration states. The snaking patterns do seem to be more complex than in previously studied continuous systems, comprising a plethora of isolated branches and also a large number of similar but not identical states, originating from the weak coupling of the phases of the individual oscillators.

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Optical observation of convective flow patterns in liquid helium

Cited by 5 publications

References 4 publications

Simulations of oscillatory convection in He3–He4 mixtures in moderate aspect ratio containers

Simulations of oscillatory convection in He3–He4 mixtures in moderate aspect ratio containers

Spatially localized binary-fluid convection

Snaking bifurcations in a self-excited oscillator chain with cyclic symmetry

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