Université de Fribourg

Nonequilibrium solid-solid phase transition in a lattice of liquid jets

Croccolo, Fabrizio ; Castellini, Stefano ; Scheffold, Frank ; Vailati, Alberto

In: Physical Review E, 2018, vol. 98, no. 6, p. 063104

Solid-solid phase transitions are commonly encountered at the atomic scale in alloys and in superatomic mesoscopic systems of colloidal particles. Here we investigate a solid-solid phase transition occurring at the macroscopic scale between lattices of liquid jets with different symmetries generated by convection in a horizontal layer of a binary liquid mixture. In the absence of a shear...

Université de Fribourg

Static versus dynamic analysis of the influence of gravity on concentration non-equilibrium fluctuations

Croccolo, Fabrizio ; Bataller, Henri ; Scheffold, Frank

In: The European Physical Journal E, 2014, vol. 37, no. 11, p. 1–5

In a binary fluid mixture subject to gravity and a stabilizing concentration gradient, concentration non-equilibrium fluctuations are long-ranged. While the gradient leads to an enhancement of the respective equilibrium fluctuations, the effect of gravity is a damping of fluctuations larger than a “characteristic” size. This damping is visible both in the fluctuation power spectrum probed by...

Université de Fribourg

Inclined layer convection in a colloidal suspension with negative Soret coefficient at large solutal Rayleigh numbers

Italia, Matteo ; Croccolo, Fabrizio ; Scheffold, Frank ; Vailati, Alberto

In: The European Physical Journal E, 2014, vol. 37, no. 10, p. 1–6

Convection in an inclined layer of fluid is affected by the presence of a component of the acceleration of gravity perpendicular to the density gradient that drives the convective motion. In this work we investigate the solutal convection of a colloidal suspension characterized by a negative Soret coefficient. Convection is induced by heating the suspension from above, and at large solutal...

Université de Fribourg

Effect of a marginal inclination on pattern formation in a binary liquid mixture under thermal stress

Croccolo, Fabrizio ; Scheffold, Frank ; Vailati, Alberto

In: Physical Review Letters, 2013, vol. 111, no. 1, p. 014502

Convective motions in a fluid layer are affected by its orientation with respect to the gravitational field. We investigate the long-term stability of a thermally stressed layer of a binary liquid mixture and show that pattern formation is strongly affected by marginal inclinations as small as a few milliradians. At small Rayleigh numbers, the mass transfer is dominated by the induced large scale...

Université de Fribourg

Mass transport properties of the tetrahydronaphthalene/n-dodecane mixture measured by investigating non-equilibrium fluctuations

Croccolo, Fabrizio ; Scheffold, Frank ; Bataller, Henri

In: Comptes Rendus Mécanique, 2013, vol. 341, no. 4–5, p. 378–385

We present preliminary near-field light scattering (NFS) data concerning the analysis of the static power spectrum and of the relaxation time constant as a function of the wave vector for non-equilibrium fluctuations (NEFs). The goal of these measurements is to obtain information about the Soret and the mass diffusion coefficients of a binary mixture undergoing thermodiffusion. In particular, we...

Université de Fribourg

Thermodiffusion of the tetrahydronaphthalene and dodecane mixture under high pressure and in porous medium

Giraudet, Cédric ; Croccolo, Fabrizio ; Galliero, Guillaume ; Pijaudier-Cabot, Gilles ; Vaerenbergh, Stefan Van ; Saghir, M. Ziad ; Montel, François ; Bataller, Henri

In: Comptes Rendus Mécanique, 2013, vol. 341, no. 4-5, p. 340-347

A thermodiffusion cell is used in order to perform Soret experiments on binary mixtures at high pressure and in the presence of a porous medium. The cell is validated at atmospheric pressure with toluene/hexane and the tetrahydronaphthalene/dodecane mixtures. The mass separation follows a diffusive behaviour when the cell is filled with a porous medium. At least three times the relaxation time is...

Université de Fribourg

A light scattering study of non equilibrium fluctuations in liquid mixtures to measure the Soret and mass diffusion coefficient

Croccolo, Fabrizio ; Bataller, Henri ; Scheffold, Frank

In: Journal of Chemical Physics, 2012, vol. 137, no. 23, p. 234202

We use dynamic near field scattering to measure the dynamics of concentration non equilibrium fluctuations at the steady-state of Soret separation. The analysis reveals that above a threshold wave vector qc, the dynamics is governed by diffusion while at smaller wave vectors, gravity dominates. From the measurements, we extract both the mass diffusion and the Soret...

Université de Fribourg

Quasi-real-time analysis of dynamic near field scattering data using a graphics processing unit

Cerchiari, Giovanni ; Croccolo, Fabrizio ; Cardinaux, Frédéric ; Scheffold, Frank

In: Review of Scientific Instruments, 2012, vol. 83, no. 10, p. 106101

We present an implementation of the analysis of dynamic near field scattering (NFS) data using a graphics processing unit. We introduce an optimized data management scheme thereby limiting the number of operations required. Overall, we reduce the processing time from hours to minutes, for typical experimental conditions. Previously the limiting step in such experiments, the processing time is now...

Université de Fribourg

Speckles generated by skewed, short-coherence light beams

Brogioli, Doriano ; Salerno, D. ; Croccolo, Fabrizio ; Ziano, R. ; Mantegazza, F.

In: New Journal of Physics, 2011, vol. 13, p. 123007

When a coherent laser beam impinges on a random sample (e.g. a colloidal suspension), the scattered light exhibits characteristic speckles. If the temporal coherence of the light source is too short, then the speckles disappear, along with the possibility of performing homodyne or heterodyne scattering detection or photon correlation spectroscopy. Here we investigate the scattering of a so-called...