Frédéric Blanc, Hugues Bodiguel, Abdoulaye Fall, Yoël Forterre, Stany Gallier, Georges Gauthier, Elisabeth Guazzelli, Elisabeth Lemaire, Anaël Lemaitre, Henri Luissier, Laurent Lobry, Jérôme Martin, Bloen Metzger, Guillaume Ovarlez (organiser), François Peters, Olivier Pouliquen
by Guillaume Ovarlez
26 June – 1 July, 2017
Concentrated suspensions of particles are often found in geophysics (debris flows, mud…) and in the industry (foodstuff, fresh concrete…). Understanding the flow properties of these materials is crucial for the most realistic possible prediction of natural hazards, to help designing complex building materials that can be placed easily, etc. In these systems, direct contacts between particles play a fundamental role, both through the formation of percolating networks that may lead to jamming and through collisions between particles that may lead to shear-induced inhomogeneities. A possible way to address these problems is to use model materials, which allow to combine numerical, experimental, and theoretical works on a well-defined system.
Fondation des Treilles has brought together sixteen researchers for a four-day workshop. These researchers are members of six French research laboratories involved in the most recent developments in the field, which now allow to consider the development of a fine macroscopic description of the behavior of suspensions in relation to their physical properties.
This stay has allowed the synthesis of results obtained by the various groups on similar materials but with different devices, which had previously shown apparent inconsistencies. Each aspect of the behavior (viscosity, normal stress differences, particle stresses, shear thinning, shear thickening, etc.) of the suspensions have been discussed in detail until a coherent macroscopic description emerged and a microscopic interpretation was proposed. After these rich discussions, two of the participants proposed to write a review paper. In addition, the discussions have revealed the need to better characterize the surface interactions (friction, colloidal forces) between particles; it has thus been proposed to carry out this characterization in the near future by means of direct measurements (AFM) and indirect measurements (study of transients) with the particles constituting the suspensions already studied in detail by the various groups. This work should bring consistency between the results and give rise to a publication of reference in the field.
All the participants have highly appreciated the unique hospitality offered by the Fondation des Treilles, which allowed for deep intellectual work freed from all contingencies, and would like to warmly thank the whole team of the Fondation.