Confined states of traveling-wave convection

Surko, C. M.; Ohlsen, Daniel R.; Yamamoto, S. Y.; Kolodner, Paul

doi:10.1103/physreva.43.7101

Cited by 31 publications

(28 citation statements)

References 16 publications

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“…These localized states consist of travelling waves under a stationary or slowly drifting envelope (Kolodner et al 1989;Steinberg et al 1989;Surko et al 1991;Barten et al 1995). States of this type can also undergo collisions (Kolodner 1991b;Iima & Nishiura 2009;Taraut, Smorodin & Lücke 2012;Watanabe et al 2012) but are quite different from the drifting localized states studied here which are time-independent in the moving frame.…”

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confidence: 99%

Travelling convectons in binary fluid convection

et al. 2013

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Binary fluid mixtures with a negative separation ratio heated from below exhibit steady spatially localized states called convectons for supercritical Rayleigh numbers. With no-slip, fixed-temperature, no-mass-flux boundary conditions at the top and bottom stationary odd-and even-parity convectons fall on a pair of intertwined branches connected by branches of travelling asymmetric states. In appropriate parameter regimes the stationary convectons may be stable. When the boundary condition on the top is changed to Newton's law of cooling the odd-parity convectons start to drift and the branch of odd-parity convectons breaks up and reconnects with the branches of asymmetric states. We explore the dependence of these changes and of the resulting drift speed on the associated Biot number using numerical continuation, and compare and contrast the results with a related study of the Swift-Hohenberg equation by Houghton & Knobloch (Phys. Rev. E, vol. 84, 2011, art. 016204). We use the results to identify stable drifting convectons and employ direct numerical simulations to study collisions between them. The collisions are highly inelastic, and result in convectons whose length exceeds the sum of the lengths of the colliding convectons.

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Travelling convectons in binary fluid convection

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“…In this physical system there is a remarkable phenomenon in one-dimensional geometries, in which finite amplitude convection can coexist stably with regions of zero flow. The nature of these states was studied with precision [3]. This work motivated new theoretical treatments of this striking effect.…”

Section: Traveling Wave Phenomenamentioning

confidence: 99%

DOE Final Technical Report for Grant Number DE-FG03-90ER14148

Surko¹

2004

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858 534 6880; csurko@ucsd.edu OverviewThis project focused on understanding the dynamics of a well-controlled fluid system driven far from equilibrium. The goal of the work was to gain a quantitative understanding of the role that traveling waves play in determining patterns and dynamics in such systems. Convection was studied in a horizontal layer of a binary fluid mixture of ethanol and water confined in a variety of interesting geometries, including a narrow annulus, to study one dimensional phenomena, and a large aspect ratio container to study two-dimensional phenomena. In these mixtures, the Soret effect couples the temperature and concentration fields leading to a wide range of dynamical behavior not present in convection in pure fluids. In particular, over a wide range of parameters, when the fluid is heated from below, convection takes the form of traveling waves composed of locally parallel rolls that move perpendicular to the roll axes. The system thus provides an insightful model for studying traveling-wave phenomena in systems driven far from equilibrium. Over the course of the project, a number of important questions were addressed. To a lesser extent, variants of this situation were also studied, including the patterns and dynamics when the fluid is heated from above. At the end of the grant, work focused on so-called non-Boussinesq effects, where there the fluid parameters vary with height in the convection cell, beyond that which can be taken into account by a thermal expansion coefficient. Technical approachBeyond the conventional techniques to study convection in a thin horizontal fluid layer with good temperature control of the upper and lower boundaries, techniques were developed to study very large convection cells. As a result, patterns of large lateral extent, D, could be investigated (i.e., D ≥ 40d, where d is the height of the fluid layer, and the pattern wavelength, λ = 2d). Experimental capabilities were developed to achieve good temperature uniformity over annular, circular, rectangular and oval convection cells as large as 21 cm in lateral extent. The entire pattern could be visualized from above using the shadowgraph technique. A shadowgraph was developed that is capable of imaging the entire pattern with excellent sensitivity and uniformity, free from distortions, over the entire the entire pattern.

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“…Out of these states emerge stable stationary spatially localized structures embedded in a background of small amplitude standing waves (see fig-3). In 1990 P. Kolodner [36,9,[37][38][39], presented evidence for the reflection of traveling waves in a localized structure. The relation of these states to the time-independent spatially localized states that characterize the so called pinning region is investigated by exploring the stability properties of the later, and the associated instabilities.…”

Section: Negative Soret Coefficientsmentioning

confidence: 99%

Localized structures in convective experiments

Burguete

Mancini

2014

Eur. Phys. J. Spec. Top.

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Abstract. In this work we review localized structures appearing in thermo-convective experiments performed in extended (large "aspect ratio") fluid layers. After a brief general review (not exhaustive), we focus on some results obtained in pure fluids in a Bénard -Marangoni system with non-homogeneous heating where some structures of this kind appear. The experimental results are compared in reference to the most classical observed in binary mixtures experiments or simulations. In the Bénard-Marangoni experiment we present the stability diagram where localized structures appear and the typical situations where these local mechanisms have been studied experimentally. Some new experimental results are also included.

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Confined states of traveling-wave convection

Cited by 31 publications

References 16 publications

Travelling convectons in binary fluid convection

Travelling convectons in binary fluid convection

DOE Final Technical Report for Grant Number DE-FG03-90ER14148

Localized structures in convective experiments

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