SOFT – Complex Fluids & Solids

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Suspensions and Complex Fluids

This theme deals with the flow of fluid/particles mixtures. Topics include the rheology and flow of non-Brownian suspensions of spheres or fibres, shear-thickening in colloidal systems, capillary suspensions, immersed granular flows, mixing in suspensions and porous media, as well as sedimentation and particle transport. We combine microscopic analyses at the particles scale, original rheological tools and hydrodynamic configurations in relation with industrial or geophysical applications.

Research

Publications

Projects

Research

Rheology of dense suspensions

Participants: Y. Forterre, E. Guazzelli, B. Metzger, O. Pouliquen
Collaboration: J. F. Morris (Levish Institute, USA), J. E. Butler (University of Florida, USA), P. Nott (Indian Institute of Science, Inde), S. Hormozi (Ohio University, USA), M. Wyart (EPFL, Suisse)
PhD/Post-doc: : F. Boyer (phD AMN, 2008-2011), E. Couturier (post-doc ANR, 2009-2011), B. Snook (phD U. Florida, 2012-2015), S. Shaikh (phD U. Florida, 2014-), S. Dagois-Bohy (post-doc ANR, 2014-2015), S. Hormozi (2015), F. Tapia (post-doc ANR, 2016-2019), H. Perrin (2018-2019, post-doc ERC) , A. Billon (phD AMN, 2018-)

We address the classical problem of the rheology of dense suspensions using a frictional description inspired by our work on dry granular media. The idea is to impose the particle pressure, leaving the volume fraction free to adjust to the flow conditions. This approach enables us to probe the flow behaviour of the suspension close to jamming, without encountering problems of viscosity divergence as in conventional volume-imposed rheometry. We have developed such “imposed-pressure” rheometers to characterize the rheology of non-Brownian suspensions of hard spheres and proposed constitutive laws that unifies the rheology of dry granular materials and dense suspensions. We are now extending this approach to more complex suspensions, such as suspensions of fibers, suspensions of particles immersed in a yield-stress or shear-thickening fluid, Brownian suspensions, inertial suspensions, or suspensions with frictionless particules… In parallel, we investigate the occurence of normal stress differences in these systems and particle migration effects when the shear is not homogeneous.

Shear-Thickening

Participants : Y. Forterre, H. Lhuissier, B. Metzger
Collaboration: R. Mari (Liphy, Grenoble), M. Wyart (EPFL, Lausanne), E. Lemaire (INPHYNI), P. Boustingorry (CHRYSO).
PhD/Post-doc: C. Clavaud (2015-2018, PhD ERC), B. Etcheverry (2019-), B. Darboix Texier (2019-, post-doc ERC and ANR), H. Perrin (2018-, post-doc ERC and ANR)

Shear thickening occurs in dense particulate suspensions whose viscosity increase dramatically, sometimes by several orders of magnitude, when the imposed shear rate exceeds a critical value. The properties of shear-thickening suspensions play a crucial role in the formulation of modern concretes or the design of shock absorbers. However, the physical origin of this phenomenon has long remained a puzzle. Recently, new theoretical ideas and numerical works have proposed that shear-thickening originates from a frictional transition, related to the existence of a repulsive force between grains at the microscopic scale. We are testing this scenario and its consequences on the rheology using (1) model shear thickening suspensions in which the repulsive force can be tuned; (2) new pressure-imposed rheometers adapted to colloidal-size particles that give access to the friction of the suspension. We also study the flow behavior and stability of shear-thickening suspensions in hydrodynamic configurations beyond rheometry, such as inclined planes or pipes.

Capillary flow of suspensions

Participants: Y. Forterre, E. Guazzelli, H. Lhuissier
Collaboration: M. Roché (MSC)
PhD/Post-doc: Joris Château (2015-, PhD ANR), Loren Jørgensen (post-doc ANR), Sergio Palma (post-doc ANR)

Many industrial and environmental processes involve the coupling between a particulate suspension and an interfacial flow. These applications often exhibit flow conditions that are difficuly to probe using conventional rheometry, such as elongational flow, transient deformation, confinement and capillary effects. We address these issues using controlled flow configurations and non-colloidal suspensions in order to identify the effect of the different suspension’s parameters (solid fraction, particle diameter, fluid’s viscosity, wettability). Various canonical situations have been considered, such as the impact of solid objects onto a granular suspension, the impact on drops on a solid surface, the pinch-off of capillary bridges, the breakup of jets or the dip-coating of particulate suspensions.

Mixing

Participants: H. Lhuissier, B. Metzger
Collaboration: J. E. Butler (University of Florida, USA), X. Yin (Collorado school of Mines, USA), E. Villermaux and P. Meunier (IRPHE), T. Le Borgne (Geosciences Rennes), Yann Boursiac (INRA Montpellier)
PhD/Post-doc: P. Phong (PhD U. Florida, 2011-2016), M. Souzy (PhD 2013-2016), R. Turuban (2018-2019, Labex MEC)

Sheared particulate suspensions constitute a very unique system where efficient mixing spontaneously occurs even under low Reynolds number conditions. The intense dispersion and mixing properties of sheared suspensions arise from the presence of particles which confer to the interstitial fluid a stochastic component. Understanding how mixing proceeds in sheared particulate suspensions has applications for instance to be able to predict the transport of drugs or oxygen in blood flow, the homogenization of adjuvants during concrete preparation or the transport of nutrients inside certain biological cells. In this project, we aim at clarifying the dispersion and mixing of scalar quantities like temperature and concentration molecules that is sheared in a suspension of spherical particles. Measurements of the spatio-temporal local concentration and interstitial flow field are compared to the theoretical predictions inferred from the knowledge of the flow kinematics. We also extend our approach to mixing and transport in other complex media, such as porous materials, reactive species or plant tissues.

Sedimentation and Particle Transport

Participants: L. Bergougnoux, G. Bouchet, M. Nicolas, E. Guazzelli.
Collaboration: E. Climent (IMFT, Toulouse), J. Dušek (Icube, Strasbourg), A. Hammouti (IFP-EN, Solaize), G. Verhille (IRPHE)
PhD/Post-doc: D. Chehata (PhD 2004-2007), F. Pignatel (2007-2010, Ministère), B. Marchetti (2015-2018, Ministère), O. Ait Oucheggou (CEA/AMU), D. Lopez (post-doc Labex/ANR), S. Bounoua (post-doc ANR)

Although sedimentation can be considered as one of the simplest examples of suspension flow, much remains unknown about the fundamental properties of sedimenting suspensions. The problem that one encounters lies in the long range nature of the multibody hydrodynamic interactions between particles. The situation becomes even more complicated when inertia is added, when particles become more complex or when they are transported by a flow. We address these issues by studying the sedimentation and transport of particles both at low Reynolds numbers and when inertial effects start to be important. Particles can be spheres or anisotropic objects like fibres, they can be rigid or soft, isolated or in assembly like in clouds of particles. The external fluid can be still or in motion, with temporal and spatial fluctuations. Our approach combine idealized experiments and simple numerical simulations to identify the physical mechanisms and test the different models.

Flow of immersed granular materials

Participants : P. Aussillous, E. Guazzelli, M. Médale, O. Pouliquen
Collaborations : J. Chauchat (LEGI), M. Wyart (EPFL), H. Capart (Taïwan)
PhD/Post-doc: M. Ouriemi (PhD 2004-2007), M. Paihla (PhD 2005-2008), L. Rondon (PhD AMX, 2008-2011), J. Chauchat (2008-2009), F. Tapia (post-doc Labex 2018-2019)

Erosion, sediment transport and submarine avalanches are geophysical phenomena that involve the coupling between a flow (interstitial fluid pressure, external shear stress) and an immersed granular material. We address these situations at the laboratory scale using model particulate systems and fluids. We have studied the onset of sediment transport by a laminar shear flow and the transport law above the threshold, the instability of the sediment layer and dune formation, avalanche triggering and flow of immersed grains. Experimental results are analyzed within two-phase continuum frameworks, in which we incorporate the frictional rheologies identified in the group.

Flow of Complex Fluids

Participants : Y. Forterre, O. Pouliquen
Collaborations : N. Balmforth
PhD/Post-doc: L-H Luu PhD (2007-2011 Ministère)

Granular materials and dense suspensions are not the only example of media that exhibit a solid-to-liquid flow transition. Complex fluids such as foams, paste, gels or concentrated emulsion also experience a yield-stress below which they behave like a solid and above which they flow like a liquid. These media are most often studied in rheometers. We have investigated the flow behavior of model yield-stress fluids such as Carbopol gels or clays suspensions in more unusual configurations such as drop impact or horizontal oscillation. These situations reveal the importance of elasticity or thixotropic effects in the unsteady and transient flow response of yield-stress fluid.