Bubbling reduces intermittency in turbulent thermal convection

Lakkaraju, Rajaram; Toschi, Federico; Lohse, Detlef

doi:10.1017/jfm.2014.33

Cited by 14 publications

(36 citation statements)

References 51 publications

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“…For small values of the coupling parameter k, the chaotic regime is asynchronous; that is, ̸ = . Transition from asynchronous to synchronous generation occurs through the intermittency of "bubbling" type [28,29]. Figure 14 shows that the variation of the control parameters allows different behaviors which are periodic or chaotic behavior.…”

Section: Remarkmentioning

confidence: 99%

Multistability Analysis and Function Projective Synchronization in Relay Coupled Oscillators

et al. 2018

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Regions of stability phases discovered in a general class of Genesio−Tesi chaotic oscillators are proposed. In a relatively large region of two-parameter space, the system has coexisting point attractors and limit cycles. The variation of two parameters is used to characterize the multistability by plotting the isospike diagrams for two nonsymmetric initial conditions. The parameters window in which the jerk system exhibits the unusual and striking feature of multiple attractors (e.g., coexistence of six disconnected periodic chaotic attractors and three-point attraction) is investigated. The second aspect of this study presents the synchronization of systems that act as mediators between two dynamical units that, in turn, show function projective synchronization (FPS) with each other. These are the so-called relay systems. In a wide range of operating parameters; this setup leads to synchronization between the outer circuits, while the relaying element remains unsynchronized. The results show that the coupled systems can achieve function projective synchronization in a determined time despite the unpredictability of the scaling function. In the coupling path, the outer dynamical systems show finite-time synchronization of their outputs, that is, displaying the same dynamics at exactly the same moment. Further, this effect is rather general and it has a wide range of applications where sustained oscillations should be retained for proper functioning of the systems.

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Section: Remarkmentioning

confidence: 99%

Multistability Analysis and Function Projective Synchronization in Relay Coupled Oscillators

et al. 2018

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“…The studies of Lakkaraju et al (2011Lakkaraju et al ( , 2013, Lakkaraju, Toschi & Lohse (2014) and Oresta et al (2009) focus on the modification of the Rayleigh-Bénard convection by a disperse vapour bubble phase. Lakkaraju et al (2011) in particular identified two opposite effects: on the one hand, the latent heat of vapour tends to decrease the temperature variance, which should reduce convection; on the other hand, the bubble growth due to the heat absorption causes additional buoyancy effects and agitation sources.…”

Section: Introductionmentioning

confidence: 99%

“…Lakkaraju et al (2011) in particular identified two opposite effects: on the one hand, the latent heat of vapour tends to decrease the temperature variance, which should reduce convection; on the other hand, the bubble growth due to the heat absorption causes additional buoyancy effects and agitation sources. The presence of the vapour bubbles was found to drastically reduce the intermittency in both temperature and velocity fields (Lakkaraju et al 2014). …”

Section: Introductionmentioning

confidence: 99%

Turbulent thermal convection driven by heated inertial particles

et al. 2016

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This is an author-deposited version published in: http://oatao.univ-toulouse.fr/ Eprints ID: 18470Open Archive Toulouse Archive Ouverte (OATAO) OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. The heating of particles in a dilute suspension, for instance by radiation, chemical reactions or radioactivity, leads to local temperature fluctuations in the fluid due to the non-uniformity of the disperse phase. In the presence of a gravity field, the fluid is set in motion by the resulting buoyancy forces. When the particle density is different than that of the fluid, the fluid motion alters the spatial distribution of the particles and possibly strengthens their concentration inhomogeneities. This in turn causes more intense local heating. Direct numerical simulations in the Boussinesq limit show this feedback loop. Various regimes are identified depending on the particle inertia. For very small particle inertia, the macroscopic behaviour of the system is the result of many thermal plumes that are generated independently of each other. For significant particle inertia, clusters of particles are observed and their dynamics controls the flow. The emergence of very intermittent turbulent fluctuations shows that the flow is influenced by the larger structures (turbulent convection) as well as by the small-scale dynamics that affect particle segregation and thus the flow forcing. Assuming thermal equilibrium between the particles and the fluid (i.e. infinitely fast thermal relaxation of the particle), we investigate the evolution of statistical observables with the change of the main control parameters (namely the particle number density, the particle inertia and the domain size), and propose a scaling argument for these trends. Concerning the energy density in the spectral space, it is observed that the turbulent energy and temperature spectra follow a power law, the exponent of which varies continuously with the Stokes number. Furthermore, the study of the spectra of the temperature and momentum forcing (and thus of the concentration/temperature and velocity/temperature correlations) gives strong support to the proposed feedback loop mechanism. We then discuss the intermittency of the flow, and analyse the effect of relaxing some of the simplifying assumptions, thus assessing the relevance of the original studied configuration. To cite this version:

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“…Boiling RB flow has been numerically simulated in recent years [66][67][68][69][70][71]. The simulations consider RB convection as the reference flow and compare several aspects of it with the 2-phase flow.…”

Section: Vapor-bubble Nucleation In Rayleigh-bénard Flowmentioning

confidence: 99%

“…[66][67][68][69][70][71]. In these studies a constant number of deliberately introduced bubbles (bubble nucleation and detachment was not simulated), with arbitrarily chosen diameters of several tens of µm, was seen to significantly change the structure of the convective flow.…”

Section: Introductionmentioning

confidence: 99%

Vapor bubble nucleation, dynamics, and heat flux in turbulent Rayleigh-Bénard convection

Guzman¹

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Nederlandse titel: Dampbel nucleatie, dynamiek en warmtestroom in turbulente Rayleigh-Bénard convectie Cover:Lateral shadowgraph image of 2-phase turbulent Rayleigh-Bénard convection. The area at the bottom plate where bubble-nucleation occurred is centrally located. The rising bubbles are detectable as dark dots located above the nucleating area and across the cell; the thermal plumes (coherent elongated structures) can be distinguished to be forming the large scale circulation. Back cover:Lateral shadowgraph image of 1-phase turbulent Rayleigh-Bénard convection.Publisher:

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Bubbling reduces intermittency in turbulent thermal convection

Cited by 14 publications

References 51 publications

Multistability Analysis and Function Projective Synchronization in Relay Coupled Oscillators

Multistability Analysis and Function Projective Synchronization in Relay Coupled Oscillators

Turbulent thermal convection driven by heated inertial particles

Vapor bubble nucleation, dynamics, and heat flux in turbulent Rayleigh-Bénard convection

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