Physics of smectic membranes

We analyze a solenoidal motion in a vertically vibrated freely suspended thin smectic film. We demonstrate analytically that transverse oscillations of the film generate two-dimensional vortices in the plane of the film owing to hydrodynamic nonlinearity. An explicit expression for the vorticity of the in-plane film motion in terms of the film displacement is obtained. The air around the film is proven to play a crucial role, since it changes the dispersion relation of transverse oscillations and transmits viscous stresses to the film, modifying its bending motion. We propose possible experimental observations enabling to check our predictions.

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“…[7,8]. Smectic liquid crystals are remarkable layered materials which can form a rich variety of structures.…”

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confidence: 99%

Nonlinear generation of vorticity in thin smectic films

2016

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“…A peninsula consisting of many layers of smectic appears at the antinode and its shape adapts to the forcing. However, smectic films of constant thickness are also easily obtained; in this latter case, they are perfect membranes with eigenfrequencies following the Rayleigh law [6]. Brazovskaia and Pieranski [3] also observed a self-tuning property: when a smectic film is loaded with a small bead, it adjusts its position with the forcing frequency.…”

Section: Introductionmentioning

confidence: 97%

A self-adaptative oscillator

Boudaoud¹,

Couder²,

Amar³

1999

Eur. Phys. J. B

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Abstract. The dynamics of a system where a mass is free to slide on a vibrating string is investigated as the excitation frequency is varied. One degree of freedom is thus added to the system studied by Helmholtz in which a mass was fixed on a vibrating string. This new system exhibits a specific dynamics characterized by the existence of a self-adaptative behaviour. When the driving frequency falls into wide and well defined frequency bands, a long transient is observed by which the mass adjusts its position so that the whole system becomes resonant. In the gaps between these bands, bifurcations give other equilibrium positions. A theoretical model is proposed. It accounts for all the experimental results. In the case where two masses are present on the string, two degrees of freedom are added and the set of equilibrium positions would be expected to be infinite. However, in the experiment, the two masses are observed to go to positions where they are symmetrical with respect to the middle of the string. A selection mechanism due to the string stretching is pointed out.

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“…The film is spanned by a rectangular film holder consisting of a U-shaped frame and a movable wire. An application of this method to the investigation of smectic films has been proposed in [148] and [149]. The smectic film is prepared on a rectangular frame with a movable side attached to a pendulum.…”

Section: Methods For Surface Tension Measurementsmentioning

confidence: 99%

Surfaces and Interfaces of Free-Standing Smectic Films

Schüring¹,

Stannarius²

2004

Molecules in Interaction With Surfaces and Interfaces

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Abstract. Free-standing smectic films are unique fluid objects with an exceptionally large surface-to-volume ratio. They are excellently suited for studies of surface and interface properties of liquids. We describe surface tension measurements in the smectic and isotropic phases, with particular emphasis on anomalies near the phase transitions. A model that considers the excess surface entropy of ordered surface layers is applied to describe the experimental observations qualitatively and quantitatively. From the geometrical properties of isotropic droplets in free-standing films and from the forces acting on these droplets, interface tensions between the smectic and isotropic phases are derived. Finally, we report measurements of the gas permeation through smectic films and develop a model for the description of the film-thickness dependence of the permeation coefficient.

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Physics of smectic membranes

Cited by 197 publications

References 5 publications

Nonlinear generation of vorticity in thin smectic films

Nonlinear generation of vorticity in thin smectic films

A self-adaptative oscillator

Surfaces and Interfaces of Free-Standing Smectic Films

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