"uctuation theorem in turbulent "ows
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PACS 05.40.-a – Fluctuation phenomena, random processes, noise, and Brownian motion
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We here present the complete analysis of experiments on driven Brownian motion and electric noise in a RC circuit, showing that thermodynamic entropy production can be related to the breaking of time-reversal symmetry in the statistical... more
We here present the complete analysis of experiments on driven Brownian motion and electric noise in a RC circuit, showing that thermodynamic entropy production can be related to the breaking of time-reversal symmetry in the statistical description of these nonequilibrium systems. The symmetry breaking can be expressed in terms of dynamical entropies per unit time, one for the forward process and the other for the time-reversed process. These entropies per unit time characterize dynamical randomness, i.e., temporal disorder, in time series of the nonequilibrium fluctuations. Their difference gives the well-known thermodynamic entropy production, which thus finds its origin in the time asymmetry of dynamical randomness, alias temporal disorder, in systems driven out of equilibrium.
The surface quality of a workpiece, as it is finished by the tooling machine, can be translated into a set of numbers (one or more) which depend on the specific measuring procedures. We illustrate this with respect to the three classes of... more
The surface quality of a workpiece, as it is finished by the tooling machine, can be translated into a set of numbers (one or more) which depend on the specific measuring procedures. We illustrate this with respect to the three classes of profilometer techniques either available or suggested, namely: mechanical profilometers, detection of the angular scattering diagram, speckle correlation. A mechanical profilometer yields a value of roughness averaged over the size of a diamond point which fingers the surface [1 ]. Furthermore, the diamond finger is cut at a given angle (e.g. 45°), and the measurement o f a roughness profile steeper than that would give wrong values. Hence, associated information has a resolution limited by the above size and steepness requirements. In the second case, using scattering techniques, the surface is illuminated by an e.m. wave (either at microwave or optical frequencies) and the angular distribution of the scattered intensity is associated with the ave...
Convective patterns with different symmetries can develop in RayleighBenard convection. When the transport coefficients of the fluid are temperature dependent (non-Boussinesq conditions) a hexagonal pattern is stable near threshold, but... more
Convective patterns with different symmetries can develop in RayleighBenard convection. When the transport coefficients of the fluid are temperature dependent (non-Boussinesq conditions) a hexagonal pattern is stable near threshold, but it is replaced by a pattern of rolls when the heating rate is increased still further. We present here recent experimental results on the transition between a hexagonal pattern and a pattern of rolls in convection in pure water under non-Boussinesq conditions. The convective cell is cylindrical with a liquid depth d = 2.00 mm and a diameter D = 72 mm. This gives an aspect ratio F = D/2d = 18. The Prandtl number of water at the mean temperature of 28°C is P = 5.81. The general features of the pattern are determined qualitatively by a shadowgraph technique. Heat-flow and optical measurements enable us to obtain quantitatively local and global characteristics of the pattern. The optical technique is based on the deflections of a laser beam that crosses the fluid layer in the vertical direction. This technique allow us to reconstruct the temperature field averaged on the vertical direction. More details about the experimental set-up can be found elsewhere.1
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Experimental results concerning the interaction of a fully developed turbulent flow with a perturbation properly generated in the physical domain, are presented. By means of a conditional averaging technique, it has been possible to... more
Experimental results concerning the interaction of a fully developed turbulent flow with a perturbation properly generated in the physical domain, are presented. By means of a conditional averaging technique, it has been possible to extract informations on the response function of the turbulent flow. Satisfactory agreement with the DIA Kraichnan’s theory prediction, is also observed.
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ABSTRACT
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Research Interests: Mathematical Physics, Physics, Statistical Physics, Classical Physics, Brownian Motion, and 12 moreFluctuation Theorem, Chaotic System, Chaotic Systems, Time Dependent, Quantum Harmonic Oscillator, Stochastic system, Point of View, Experimental Data, Molecular Motor, Driving force, Chaotic, and entropy production
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Karhunen-Loeve decomposition has been used in order to compute the number of the fundamental degrees of freedom in a complex spatiotemporal dynamics. The method has been applied on experimental and numerical data. In both cases the number... more
Karhunen-Loeve decomposition has been used in order to compute the number of the fundamental degrees of freedom in a complex spatiotemporal dynamics. The method has been applied on experimental and numerical data. In both cases the number of degrees of freedom found by this method is very close to the fractal dimension of the attractor or the Lyapunov dimension.
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Surface waves instability has been experimentally studied in a cylindrical basin subjected to a horizontal oscillation. We show that the presence of two modes, respectively parallel and perpendicular to the direction of the forcing, may... more
Surface waves instability has been experimentally studied in a cylindrical basin subjected to a horizontal oscillation. We show that the presence of two modes, respectively parallel and perpendicular to the direction of the forcing, may produce either a stable or a time-dependent superposition of the two modes. The phase diagram of the system, the surface deformation amplitude and the features
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Multiscale correlation functions in high Reynolds number experimental turbulence, numerical simulations, and synthetic signals are investigated. Fusion Rules predictions as they arise from multiplicative, almost uncorrelated, random... more
Multiscale correlation functions in high Reynolds number experimental turbulence, numerical simulations, and synthetic signals are investigated. Fusion Rules predictions as they arise from multiplicative, almost uncorrelated, random processes for the energy cascade are tested. Leading and subleading contribution, in the inertial range, can be explained as arising from a multiplicative random process for the energy transfer mechanisms. Two different predictions for correlations involving dissipative observable are also briefly discussed.
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In this letter we report further experimental evidence of extended self-similarity in the structure functions of the velocity field of fully developed turbulence. We study the behaviour of high-order structure functions close to the... more
In this letter we report further experimental evidence of extended self-similarity in the structure functions of the velocity field of fully developed turbulence. We study the behaviour of high-order structure functions close to the Kolmogorov scale η where extended self-similarity is observed.
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A new method to measure subsonic vibrations of very small amplitude is presented. It makes use of an interferometric system plus a phase modulation of the laser light source. The accuracy is limited only by the shot noise of the laser.... more
A new method to measure subsonic vibrations of very small amplitude is presented. It makes use of an interferometric system plus a phase modulation of the laser light source. The accuracy is limited only by the shot noise of the laser. Some considerations are reported concerning the frequency spectrum of the signal and the signal to noise ratio. The experimental results show a good agreement with theory.
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Summary We describe an experiment which has been designed to measure both spatial and temporal features of turbulent thermal convection in a fluid layer heated from below. Specifically we have studied the dependence of the heat flowvs.... more
Summary We describe an experiment which has been designed to measure both spatial and temporal features of turbulent thermal convection in a fluid layer heated from below. Specifically we have studied the dependence of the heat flowvs. the Rayleigh number, the thermal boundary layer profile, the temperature probability distribution function, the frequency and wave number power spectra. All the results have
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We describe two analog electronic techniques to determine the position of a light spot on a linear photodiode array by detecting its intensity peak or its centroid. The position was detected with an accuracy of 1 and 3.5 μm by the two... more
We describe two analog electronic techniques to determine the position of a light spot on a linear photodiode array by detecting its intensity peak or its centroid. The position was detected with an accuracy of 1 and 3.5 μm by the two methods, respectively, using a 16-μm center-to-center array. As an example, the displacement of a mirror was measured with
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... Count the number of neighbors of Xi corresponding to increasing values of r from a preselected sequence of possible values, and stop when the number of neighbors exceeds for the first time min(2dM,dM ... 3. Typical behavior when too... more
... Count the number of neighbors of Xi corresponding to increasing values of r from a preselected sequence of possible values, and stop when the number of neighbors exceeds for the first time min(2dM,dM ... 3. Typical behavior when too few neighbors are chosen: card S'E(r) > dM ...
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... Date Submitted by the Author: 27-Aug-2008 Complete List of Authors: Jop, Pierre; ENSL, Laboratoire de Physique Petrosyan, Artyom; ENSL, Laboratoire de Physique Ciliberto, Sergio; ENSL, Laboratoire de Physique Keywords: ageing,... more
... Date Submitted by the Author: 27-Aug-2008 Complete List of Authors: Jop, Pierre; ENSL, Laboratoire de Physique Petrosyan, Artyom; ENSL, Laboratoire de Physique Ciliberto, Sergio; ENSL, Laboratoire de Physique Keywords: ageing, colloids, rheology, statistical physics ...
Several experimental aspects of the aging dynamics are discussed. We first introduce the general features of aging. We then describe several experimental procedures, based on the response function, which have been useful to study memory... more
Several experimental aspects of the aging dynamics are discussed. We first introduce the general features of aging. We then describe several experimental procedures, based on the response function, which have been useful to study memory and rejuvenation effects in various materials. A comparison of the results obtained in the different materials is done. The experimental analysis of the violation of the Fluctuation-Dissipation Theorem (FDT) in aging materials is presented. We describe several experiments where the violation has been studied in some details. The amplitude, the persistence time and the observable dependence of the violation observed in the experiments are analyzed. The relevance of these experimental results for recent models of aging is discussed.
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Measuring very low level signals at low frequency is a tedious task, because environmental noise increases in this frequency domain and it is very difficult to filter it efficiently. In order to counteract these major problems, we propose... more
Measuring very low level signals at low frequency is a tedious task, because environmental noise increases in this frequency domain and it is very difficult to filter it efficiently. In order to counteract these major problems, we propose a simple and generic noise subtraction technique, which mixes several features of traditional feedback techniques and those of noise estimators. As an
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We measure the energy fluctuations of a Brownian particle confined by an optical trap in an aging gelatin after a very fast quench (less than 1 ms). The strong nonequilibrium fluctuations due to the assemblage of the gel are interpreted,... more
We measure the energy fluctuations of a Brownian particle confined by an optical trap in an aging gelatin after a very fast quench (less than 1 ms). The strong nonequilibrium fluctuations due to the assemblage of the gel are interpreted, within the framework of fluctuation theorem, as a heat flux from the particle towards the bath. We derive an analytical expression of the heat probability distribution, which fits the experimental data and satisfies a fluctuation relation similar to that of a system in contact with two baths at different temperatures.
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ABSTRACT The transition between hexagons and rolls in convective patterns has been studied in pure water under non-Boussinesq conditions. The transition is characterized qualitatively by shadowgraph images and quantitatively by heat-flow... more
ABSTRACT The transition between hexagons and rolls in convective patterns has been studied in pure water under non-Boussinesq conditions. The transition is characterized qualitatively by shadowgraph images and quantitatively by heat-flow measurements and a local technique based on the deflections of a laser beam. We also show that with this local technique one can recover global quantities such as the convective heat flow.
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Experimental evidence is given that the hierarchy of the energy dissipation moments, recently proposed by She and Leveque [Phys. Rev. Lett. 72, 336 (1994)] for fully developed turbulence, is in agreement with experimental data in... more
Experimental evidence is given that the hierarchy of the energy dissipation moments, recently proposed by She and Leveque [Phys. Rev. Lett. 72, 336 (1994)] for fully developed turbulence, is in agreement with experimental data in different experimental configurations.
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Experimental evidence is reported that the scattering of sound waves by a fluid flow may be used, as a nonintrusive and nonlocal method, to characterize the space-time structure of the flow. The experiment has been performed using, as a... more
Experimental evidence is reported that the scattering of sound waves by a fluid flow may be used, as a nonintrusive and nonlocal method, to characterize the space-time structure of the flow. The experiment has been performed using, as a test flow, the von Karman vortex street behind a cylinder at a low Reynolds number (Re = 50). The results are