Time filter

Source Type

Bureau L.,CNRS Nanosciences Institute of Paris
Physical Review Letters | Year: 2010

We probe the rheology of the model liquid octamethylcyclotetrasiloxane (OMCTS) confined into molecularly thin films, using a unique surface force apparatus allowing us to explore a large range of shear rates and confinement. We thus show that OMCTS under increasing confinement exhibits the viscosity enhancement and the nonlinear flow properties characteristic of a sheared supercooled liquid approaching its glass transition. Besides, we study the drainage of confined OMCTS via the propagation of "squeeze-out" fronts. The hydrodynamic model proposed by Becker and Mugele to describe such front dynamics leads to a conclusion in apparent contradiction with the dynamical slowdown evidenced by rheology measurements, which suggests that front propagation is not controlled by large scale flow in the confined films. © 2010 The American Physical Society.

Cohen-Addad S.,CNRS Nanosciences Institute of Paris | Hohler R.,University Paris Est Creteil
Current Opinion in Colloid and Interface Science | Year: 2014

We review the state of the art in foam and highly concentrated emulsion rheology, with an emphasis on progress made over the last five years. Since the structures and physico-chemical processes relevant for foams and emulsions are closely analogous, comparing the knowledge recently gained in these two neighboring fields brings fresh insight. In this spirit, we review how the macroscopic mechanical response arises from a coupling between interfacial energy and long range molecular interactions, entropic effects, interfacial rheology, and dynamics at the droplet or bubble scale. We present experiments and models concerning elasticity, osmotic pressure, yielding and flow behavior. © 2014 Elsevier Ltd.

Akamatsu S.,CNRS Nanosciences Institute of Paris | Plapp M.,Ecole Polytechnique - Palaiseau
Current Opinion in Solid State and Materials Science | Year: 2016

Recent advances in the understanding of eutectic and peritectic two-phase pattern formation under purely diffusive transport are reviewed. The parallel progress of two key techniques, namely, in situ experimentation with model, low-melting transparent and metallic alloys in thin and bulk samples, and numerical phase-field simulations, is highlighted. Experiments and simulations are interpreted in the light of the theory of non-equilibrium pattern formation phenomena. Focus is put on microstructure selection and morphological transitions, multiscale patterns in ternary alloys, and the influence of crystallographic effects on pattern formation. Open problems, for example on crystallographic effects, irregular eutectics, and peritectic solidification, are outlined. © 2015 Elsevier Ltd. All rights reserved.

Prevot G.,CNRS Nanosciences Institute of Paris
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We have studied the Ostwald ripening of three-dimensional islands on a homogeneous surface with an original off-lattice kinetic Monte Carlo algorithm. In this algorithm, adatom trajectories are highly simplified, while still ensuring that the adatom fluxes between islands are exactly described. From the simulations, we obtained the evolution of the island size distribution over a large time range. The simulations obtained are compared with the results of numerical integration of rate equations derived from a mean-field approximation. Both results indicate that the equilibrium radius of the islands follows a power-law behavior in the limit of a very dilute phase, with an exponent close to 1/4. A general, excellent agreement is obtained, showing the validity of our approach, whereas the validity of the mean-field approximation is discussed for a very small mean island size, or for a large fraction of the surface covered by the islands. © 2011 American Physical Society.

Cohen-Addad S.,CNRS Nanosciences Institute of Paris | Cohen-Addad S.,University Paris Est Creteil | Hohler R.,CNRS Nanosciences Institute of Paris | Hohler R.,University Paris Est Creteil | Pitois O.,ParisTech National School of Bridges and Roads
Annual Review of Fluid Mechanics | Year: 2013

Aqueous foams are complex fluids composed of gas bubbles tightly packed in a surfactant solution. Even though they generally consist only of Newtonian fluids, foam flow obeys nonlinear laws. This can result from nonaffine deformations of the disordered bubble packing as well as from a coupling between the surface flow in the surfactant monolayers and the bulk liquid flow in the films, channels, and nodes. A similar coupling governs the permeation of liquid through the bubble packing that is observed when foams drain due to gravity. We review the experimental state of the art as well as recent models that describe the interplay of the processes at multiple length scales involved in foam drainage and rheology. Copyright © 2013 by Annual Reviews. All rights reserved.

Discover hidden collaborations