Emmanuelle Gouillart
Un article de Surface du verre et interfaces.
Research engineer, Saint-Gobain Recherche
Contact information
| Emmanuelle Gouillart Unité mixte Saint-Gobain/CNRS "Surface du Verre et Interfaces" | 
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Research interests and activities
Position: member of the Heterogeneous reactive materials team of the lab since 2008.
Background: statistical physics, dynamical systems, physics of fluids.
Research interests:
- Transformations of glass raw materials into silicate liquids
We investigate the physical and chemical mechanisms of the transformation of glass raw materials. The glass batch is composed of granular powders of sand and carbonates heated up to very high temperatures (1500°C) in order to form glass. The transformation of the granular pile into a silicate liquid involves a wide range of chemical reactions coupled to physical transformations of the media. With Marie-Hélène Chopinet, we study this coupled evolution using classical tools of high-temperature chemistry (thermal analyses, XRD, Raman spectroscopy) as well as imaging techniques for observing the physical structure, or complementary numerical simulations.
- Structure of reactive granular media
The structures of granular packings fascinates has fascinated physicists for many decades, yet little knowledge exists about the statistics of "reactive contacts" when different chemical populations coexist inside a packing and may react together. In particular, we're interested in characterizing the fraction of "locally segregated" grains that don't have contacts with their reactive species.
This study is motivated by our interest in glass batch melting (above paragraph) when the number of contacts between the different species determines the progress of competing solid-solid state reactions.
For simulating realistic granular pilings we use the discrete-element code LMGC90 developed at the Laboratoire de Mécanique et de Génie Civil (Montpellier) by Frédéric Dubois and collaborators.
Future projects concern the evolution of a granular packing following the dissolution of a fraction of the grains and the activation of cohesive interactions due to capillar bridges.
- Chaotic mixing of viscous and/or complex fluids
Many industrial processes require to blend together different substances, a process known as mixing. Mixing of viscous fluids is quite difficult without the aid of turbulence, yes it is possible to perform efficient stirring by choosing protocols that stretch and fold rapidly fluid elements. A simple example is a vertical spoon moved on a figure-eight trajectory inside a bowl. This is called chaotic mixing, because Lagrangian trajectories are chaotic (separate exponentially fast).
Interests/studies about mixing:
- Speed of scalar homogenization due to chaotic mixing. Efficient mixing requires to create Lagrangian trajectories that separate exponentially fast. However, it is difficult to predict the speed at which a dye is homogenized in a chaotic mixer: the dynamics of homogenization may be exponential, algebraic or exhibit various regimes. Of particular importance are the regions of space where fluid stretching is the lowest, whose properties determine the rate of mixing.
- Mixing in open flows. Contrary to closed flows (inside bowls, closed tanks, ..), mixing has been much less studied in open flows where a net current flows through a limited mixing region. We have studied the dynamics of such a transient mixing. We are currently studying different means of evaluating the efficiency of mixing in such systems.
Publications
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