Particles production in expanding color flux tube

Lyakhov, K. A.

doi:10.1134/s106377960807023x

Cited by 4 publications

(7 citation statements)

References 5 publications

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“…One of the surfaces, vibrating at a frequency f , is an ultrasonic source providing the external forcing. Previous studies on this system [10,11] have reported, in the frame of the plane-wave approximation, bistability and complex temporal dynamics, in good agreement with the corresponding experiments. In this Letter we extend the previous model considering the effect of sound diffraction and temperature diffusion in a large aperture resonator.…”

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confidence: 85%

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Ultrasonic cavity solitons

2008

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We report on a new type of localized structure, an ultrasonic cavity soliton, supported by large aspect-ratio acoustic resonators containing viscous media. The spatio-temporal dynamics of this system is analyzed on the basis of a generalized Swift-Hohenberg equation, derived from the microscopic equations under conditions close to nascent bistability. These states of the acoustic and thermal fields are robust structures, existing whenever a spatially uniform solution and a periodic pattern coexist. An analytical solution for the ultrasonic cavity soliton is also presented. 75.80.+q, 43.25.+y

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confidence: 85%

“…These equations have been used to address problems such as self-focusing and selftransparency of sound [8]. They have been also the basis for the analysis of temporal dynamic phenomena in acoustic resonators [10]. In this case, a viscous fluid is bounded by two flat and parallel reflecting surfaces.…”

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confidence: 99%

Ultrasonic cavity solitons

2008

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“…This system has been previously addressed in the frame of wave-plane approximation, showing bistability and complex temporal dynamics [3,4]. One of the surfaces, vibrating at frequency f, acts as ultrasonic force providing the external forcing.…”

Section: The Systemmentioning

confidence: 99%

Pattern Formation And Localized Structures In Acoustic Resonators Containing A Viscous Fluid

Pérez‐Arjona¹,

Sánchez‐Morcillo²,

Valcárcel³

et al. 2008

AIP Conference Proceedings

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The model equations describing a large-aspect acoustic resonator have been developed. A new type of robust localized structure, an ultrasonic cavity soliton, is exhibited by the system, both in the thermal and the pressure field. The existence of this structure has been proved by the numerical integration of the model equations. Previous experimental results show a good agreement with the theoretical predictions. A generalized Swift-Hohenberg equation has been derived in a limit, relating the thermoacoustic resonator with a larger set of pattern forming systems.

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“…The propagation of sound in such a medium has been shown to be described in terms of two coupled equations for pressure, p′, and temperature, T′, deviations [5]. A previous theoretical and experimental study in this system [6] evidenced the existence of nontrivial temporal dynamics (self-pulsations and chaos). All these studies were performed in the framework of the plane wave approximation, thus spatial coupling was ignored.…”

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confidence: 94%

“…Finally, in the transverse Laplacian operator the dimensionless transverse coordinates (x,y) are measured in units of the diffraction length l d = c 0 (t p /2ω) 1/2 , and the normalized diffusion coefficient D = χ t h /l d ². We note that when spatial derivatives are ignored the model of [6] is retrieved.…”

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Self-organization of ultrasound in viscous fluids

Sánchez‐Morcillo

Martínez-Mora

Pérez‐Arjona

et al. 2010

EPL

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We report the theoretical and experimental demonstration of pattern formation in acoustics. The system is an acoustic resonator containing a viscous fluid. When the system is driven by an external periodic force, the ultrasonic field inside the cavity experiences different pattern-forming instabilities leading to the emergence of periodic structures. The system is also shown to possess bistable regimes, in which localized states of the ultrasonic field develop. The thermal nonlinearity in the viscous fluid, together with the far-from-equilibrium conditions, are is the responsible of the observed effects.Spontaneous pattern formation is a universal behavior observed in a diverse class of far from equilibrium systems in chemistry, biology, fluid mechanics, and nonlinear optics [1,2]. The latter has recently received great attention, owing to the potential applications in all-optical signal processing devices [2]. One noticeable exception in the list of disciplines where pattern formation has been demonstrated is acoustics. Although several nonlinear dynamic phenomena have been reported in acoustics, there not exists up to now a clear evidence of self-organization of sound, in spite of the strong similarities between the behaviour of light and sound waves. On one side, the observation of patterns requires systems with a large aspect ratio or Fresnel number, a situation which is not commonly considered in acoustics. On the other side, nonlinearity in typical fluids is quadratic and of elastic nature. This circumstance, together with the absence of dispersion of sound (but not optical) waves, results in higher harmonics generation with a complicated spectrum which makes difficult the observation and analysis of spatial instabilities. We present here what we believe to be the first experimental observation of spontaneous pattern formation of a confined ultrasonic field, propagating in a viscous medium and driven far from equilibrium.The physical model we consider is an acoustic resonator or interferometer, formed by two flat, parallel and highly reflecting walls which contain a viscous fluid. One of the walls vibrates at ultrasonic frequencies f with a given amplitude. For high enough driving amplitudes, the system behaviour is nonlinear, the main source of nonlinearity being of thermal (not elastic) origin. In a viscous medium the sound velocity c depends significantly on temperature, c = c 0 (1 -σT′), where c 0 is the velocity of sound at some equilibrium (ambient) temperature, T′ denotes the variation of the medium temperature from that equilibrium due to the intense acoustic wave, and σ is the parameter of thermal nonlinearity. The propagation of sound in such a medium has been shown to be described in terms of two coupled equations for pressure, p′, and temperature, T′, deviations [5]. A previous theoretical and experimental study in this system [6] evidenced the existence of nontrivial temporal dynamics (self-pulsations and chaos). All these studies were performed in the framework of the plane wave approximation...

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Particles production in expanding color flux tube

Cited by 4 publications

References 5 publications

Ultrasonic cavity solitons

Ultrasonic cavity solitons

Pattern Formation And Localized Structures In Acoustic Resonators Containing A Viscous Fluid

Self-organization of ultrasound in viscous fluids

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