Biomedical subjects

Sylvie Cohen-Addad

Publications and source records attributed to Sylvie Cohen-Addad.

3 recordsLinked to original sources

PubMed2004

Origin of the slow linear viscoelastic response of aqueous foams.

We have studied the slow linear viscoelastic response of wet aqueous foams by macroscopic creep compliance measurements, combined to a diffusing-wave spectroscopy investigation of the local dynamics. The data strongly suggest that this rheological response arises from two distinct relaxation mechanisms: The first is due to the coarsening induced bubble rearrangements and governs the steady-state creep; the second results from the interplay between surface tension and surface viscosity of the gas-liquid interfaces and gives rise to a transient relaxation.

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PubMed2003

Dynamics of yielding observed in a three-dimensional aqueous dry foam.

We study the onset of yielding in stable three-dimensional dry foams following the start up of steady shear flow. By means of a charge-coupled device camera equipped with a small depth-of-field objective, we visualize the Plateau border network in the bulk of the foam. The onset of yielding is identified with the deformation gamma(c) for which shear induced rearrangements start occurring. We show that gamma(c) is independent of shear rate gamma; in a quasistatic regime whereas at high strain rates, a rapid increase of gamma(c) with gamma; is observed, in qualitative agreement with theoretical models. Moreover, spatiotemporal image analyses are used to determine the velocity profile in the gap. We find that this profile remains linear up to strains far beyond gamma(c). Moreover, we have studied the strain history dependence of gamma(c).

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PubMed2003

High-resolution diffusing-wave spectroscopy using optimized heterodyne detection.

We show experimentally and theoretically that the use of optimized heterodyne detection in a diffusing-wave spectroscopy experiment leads to the detection of much smaller intensity autocorrelations than with conventional (either homodyne or heterodyne) setups. This enhanced resolution may be useful for the study of longtime dynamics of multiple-scattering disordered systems.

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