Jean-marc Flesselles - Academia.edu (original) (raw)

Papers by Jean-marc Flesselles

Advances in Physics, Feb 1, 1991

Page 1. ADVANCES IN PHYSICS, 1991, VOL. 40, NO. 1, 1-51 Dynamics of one-dimensional interfaces: a... more Page 1. ADVANCES IN PHYSICS, 1991, VOL. 40, NO. 1, 1-51 Dynamics of one-dimensional interfaces: an experimentalist's view By J.-M. FLESSELLES, AJ SIMON and AJ LIBCHABER The James Franck and Enrico Fermi Institutes ...

Springer eBooks, 1988

A wide range of physical systems show broad spectrum relaxation effects which appear as stretched... more A wide range of physical systems show broad spectrum relaxation effects which appear as stretched-exponential relaxation: q(t) ~ exp(− λts).

Journal of physics, Apr 7, 1989

On the basis of a simple model of time relaxation in disordered systems (such as glasses or spin ... more On the basis of a simple model of time relaxation in disordered systems (such as glasses or spin glasses), the authors study the diffusion on clusters built on high-dimensional hypercubes. They show there exist two particular concentrations of available sites on the hypercube. The first one defines two distinct behaviours of relaxation: above p=1/2, the relaxation is purely exponential; below p=1/2, the relaxation is no longer exponential. The other case is of more interest: it is the percolation concentration. Using the unproven but argued assumption that, because of the high dimensionality of the considered space, the calculation may be mapped onto the problem of diffusion on a standard mean-field percolation cluster, they show that the relaxation should follow a stretched exponential law there with exponent 1/3. They briefly discuss the physical implications of this approach.

Journal of Physics C: Solid State Physics, 1987

The authors have carried out numerical calculations of random-walk diffusion on the vertices of h... more The authors have carried out numerical calculations of random-walk diffusion on the vertices of hypercubes up to dimension 17. Stretched exponential relaxation with an exponent tending to 1/3 if observed near the percolation threshold concentration. The results show striking similarities to relaxation above Tg in an Ising spin glass.

NATO ASI Series, 1991

The experimental setup used is a classical directional solidification one where a movable sample ... more The experimental setup used is a classical directional solidification one where a movable sample holder is displaced at a controled velocity along a temperature gradient provided by two thermally regulated copper blocks. The sample consists of a thin layer of liquid crystal (here the 4,4’-n-octylcyanobiphenyl, 8CB) sandwiched between two glass plates. The temperatures are adjusted such that the liquid crystal undergoes a phase transition above the gap between the two blocks. The 8CB is isotropic down to 40.5°C where it becomes nematic through a weakly first order transition. The sample is properly moved along the gradient so that the amount of the more ordered phase (here the nematic one) is increased with respect to the less ordered one (the isotropic one); hence the name directional ordering experiment. The experimental setup is mounted on an optical microscope to observe the interface and eventually record it for later analysis (Oswald et al., 1987; Bechhoefer, 1988; Simon et al., 1988; Simon and Libchaber, 1990).

Physics Letters A, 1989

The self.~consistent equations ofThouless, Anderson and Palmer describing the mean-field spin-gla... more The self.~consistent equations ofThouless, Anderson and Palmer describing the mean-field spin-glasses have been rewritten in an iterative way which can be assimilated with a dynamical process. We have studied them numerically near the transition temperature in the (q,~) space, where q is the Edwards-Anderson parameter. Whereas in the paramagnetic phase the only stable solution is the trivial one q=0, q=0, in the spin-glass phase the system finally reaches a stable limit cycle, whose dimensions follow the usual static scaling laws.

Physical Review E, 1994

A type of excitable mediuman elastic excitable mediumhas been created by incorporating the Belous... more A type of excitable mediuman elastic excitable mediumhas been created by incorporating the Belousov-Zhabotinsky reaction into a polyacrylamide-silica gel. It permits one to address the problem of how the cardiac muscle contractions affect the dynamics of rotating spiral waves. Investigations of the effects of mechanical deformations on the excitation wave propagation exhibit a resonance dynamics of vortices. For equal frequencies of deformation and of vortex rotation, vortices drift. The drift velocity is about 3% of the excitation wave velocity, for a 50% elongation. The direction of the drift does not coincide with the stretching direction and can be varied by changing the phase shift between deformations and vortex rotation. Numerical calculations suggest that the effects of mechanical deformations on excitation wave propagation are independent of the exact nature of the excitable medium.

Nonlinear Phenomena in Fluids, Solids and Other Complex Systems, 1991

Segregation of impurities at a nematic/isotropic interface induces the Mullins-Sekerka instabilit... more Segregation of impurities at a nematic/isotropic interface induces the Mullins-Sekerka instability. Above a critical velocity tne interface initially flat destabilizes to a wavy pattern. As the velocity is increased a series of dynamical modes are observed. Those which break the parity of the pattern, travelling waves and solitary modes, also select the wavelength.

Physical Review B, 1988

%e discuss nonexponential relaxation in spin glasses and glasses above the ordering temperature T... more %e discuss nonexponential relaxation in spin glasses and glasses above the ordering temperature Tg in terms of the morphology of the set of available states in con6guration space. Data from simulations on Ising spin glasses and from experiments on a variety of real glassy systems (spin glasses, a polymer, a molten salt, an organic liquid, and an ionic conductor) show behavior very similar to that suggested by the model.

The European Physical Journal B, 2007

We report on an experimental study of an array of liquid columns, hanging below an overflowing ci... more We report on an experimental study of an array of liquid columns, hanging below an overflowing circular dish fed at a constant flow-rate. This one-dimensional pattern exhibits spatio-temporal chaos as well as a host of ordered dynamical regimes, depending on flow-rate, initial positions, number of columns, and liquid properties. In this paper, we present stability diagrams obtained with liquids of different properties and an extensive quantitative study of the ordered, predictable dynamical states. Some destabilization mechanisms of these regimes are also presented.

APS, Mar 1, 1997

We present a systematic survey of the dynamics of a single spiral wave in the Belousov-Zhabotinsk... more We present a systematic survey of the dynamics of a single spiral wave in the Belousov-Zhabotinsky reaction in a spatial open reactor. The asymptotic pitch ps and period Ts of a simply rotating spiral are measured for various concentrations of sulfuric acid, sodium bromate, and malonic acid. At a particular chemical composition, the spiral selects unique, well-defined values of ps and Ts from among those allowed by the dispersion relation of the medium. This selection follows the scaling relation: ps ~ T_s^1/2. The overall scale is set by the chemical control parameter which we show to be the normalized product of the sulfuric acid and sodium bromate concentrations. By imposing a longer rotation period T on the spiral, resulting in a larger pitch p, we determine the dispersion relation c=p/T vs. T for several different chemical compositions. An appropriate rescaling collapses all dispersion curves onto a single line. We propose a functional form for the dispersion relation, with an interpretation based on the underlying chemistry of the BZ reaction.

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Europhysics Letters (EPL), 1996

A stably rotating spiral wave in the Belousov-Zhabotinsky reaction studied in an open spatial rea... more A stably rotating spiral wave in the Belousov-Zhabotinsky reaction studied in an open spatial reactor becomes unstable when forced by a periodic chemical oscillation. The instability starts from the spiral center and occurs when the ratio of the spiral-rotation period to that of the forcing is close to 3/2. The resulting disordered state involves drifting line sources that emit waves in both directions. These unusual objects are reminiscent of the travelling hole solutions to the one-dimensional complex Ginzburg-Landau equation.

Physical Review Letters, 1991

Crystallization of two-dimensional domains in monolayer films of the soluble surfactant sodium do... more Crystallization of two-dimensional domains in monolayer films of the soluble surfactant sodium dodecyl sulfate exhibits a smooth shape transition from disks to hexagons. This transition is experimentally proven to be mainly a kinetic effect. The appearance of negative curvature marks the onset of shape instabilities. A simple geometric model based on the local interplay between line tension and crystalline anisotropy accounts for the observed behaviors. It is argued that the observed shapes are generic and insensitive to details of the actual mechanisms. =

International Journal of Heat and Mass Transfer, 2012

Industrial production of glass involves natural convection of viscous fluids heated from above in... more Industrial production of glass involves natural convection of viscous fluids heated from above in shallow cavities. This problem is revisited by means of extensive numerical simulations and analytical expansions for a 2D configuration. This approach yields exact and approximate analytical expressions that can be practically used to evaluate the convective intensity and the heat flux in the different regimes. These results also confirm that the control parameter for this problem is the product of the Rayleigh number, based on the height of the enclosure, by the cavity aspect ratio squared whatever the top boundary conditions.

Transition towards spatio-temporal chaos in one-dimensional interfacial patterns often involves t... more Transition towards spatio-temporal chaos in one-dimensional interfacial patterns often involves two degrees of freedom: drift and out-of-phase oscillations of cells, respectively associated to parity breaking and vacillating-breathing secondary bifurcations. In this paper, the interaction between these two modes is investigated in the case of a single domain propagating along a circular array of liquid jets. As observed by Michalland and Rabaud for the printer's instability Rabaud92, the velocity V_g of a constant width domain is linked to the angular frequency ω of oscillations and to the spacing between columns λ_0 by the relationship V_g = αλ_0 ω. We show by a simple geometrical argument that α should be close to 1/ π instead of the initial value α = 1/2 deduced from their analogy with phonons. This fact is in quantitative agreement with our data, with a slight deviation increasing with flow rate.

Analysis of a chemical model for the BelousovÈZhabotinsky reaction leads to an analytic form for ... more Analysis of a chemical model for the BelousovÈZhabotinsky reaction leads to an analytic form for the dispersion relation for waves travelling in such a medium. It is found that the velocity varies as the hyperbolic tangent of the normalized period. Data analysis suggests that the normalization time is the selected spiral period for the medium. This result agrees with previously published data, one-dimensional as well as two-dimensional, all of which can be rescaled onto a single dimensionless curve. It thus provides a unifying approach to all waves in this reaction. 1

The present invention relates to a method of manufacturing a glass comprising providing a stream ... more The present invention relates to a method of manufacturing a glass comprising providing a stream (F) horizontal liquid glass and the mixture of the flows, characterized in that said mixing is carried out by rotating n trees ( 10, 20), n integer equal to or greater than two, each having an axis, two shafts (10, 20) adjacent being separated by a distance (D) with their axes parallel and with each of these two shafts (10, 20) adjacent which is connected to at least one rod (11, 12; 21, 22) which is located at least partially in said flow (F) and each of these rods (11, 12, 21, 22) having an axis parallel to the axis of the shaft to which it is connected in that for said two adjacent shafts at least, the distance between the axis of a rod and the axis of the shaft to which it is connected is greater than or equal to 9/20 of the distance (D) between the axes of these two shafts, and in that said two adjacent shafts are driven in c GAINST-rotation relative to each other with, in the direc...

Archetypes des systemes desordonnes, les verres de spin ont ete parmi les plus etudies tant exper... more Archetypes des systemes desordonnes, les verres de spin ont ete parmi les plus etudies tant experimentalement que theoriquement. Ainsi leurs modeles theoriques, bien definis, donnent lieu a des etudes permettant une comprehension generale de la physique du desordre, statique ou dynamique. Alors que celle-la a beau coup progresse, celle-ci reste largement incomprise. Nous introduisons a l'etude des verres de spin par un panorama des systemes experimentaux et de leurs proprietes ainsi qu'une description des modeles theoriques reconnus. Nous insistons sur leurs apports a la comprehension des transitions de phases et presentons les idees originales introduites pour modeliser les systemes realistes. Le comportement dynamique produit par simulations est comparable a la realite, mais n'est pas correctement decrit par les theories phenomenologiques que nous discutons. Comme de nombreux systemes physiques desordonnes ont un comportement dynamique analogue, des modeles generaux o...