Tunable interactions inside deformable porous media
Multiphase flows are ubiquitous in geophysical, biophysical or even industrial systems, ranging from flow in the blood system, to powder flows in engineering or fractures of granular media. These complex systems involve mesoscopic interactions at the scale of grains with macroscopic repercussions, revealing complex structures. These structures have been extensively studied by members of the PoreLab laboratory in Norway in various projects involving different experiments in recent years:
- buldozing, transport of particles in a tube showing regular plugs, see ,
- labyrinthe, 2D-equivalent of buldozing where a mixture of liquid and particles in a Hele-Shaw cell is slowly dragged revealing labyrinthine shapes, see [2, 3],
- aerofracture, where air is injected into a dense system of constrained grains in a Hele- Shaw cell, resulting in the appearance of granular fractures in the medium, see .
On the other hand, the influence of interactions between grains is of primary importance. These interactions are of a multiple nature, but it has been proposed in recent years [5, 6, 7] to use magnetic grains under the influence of an external field. We will use ferromagnetic particles which, when subjected to an external magnetic field B, acquire a magnetization. This magnetization can then be used to induce and control dipole/dipole interactions between particles in the presence of a uniform applied field. The maximum of this interaction energy is found when the momenta of the particles are aligned, leading to the creation of chains and clusters aligned with the forcing magnetic field.
During this project we will conduct studies to reproduce the experiments listed above using magnetic particles to control mesoscopic interactions within our systems. In parallel, a study of the effect of clogging, at the origin of the formation of the observed structures, will be carried out under magnetic interaction conditions. Clogging is the creation of a plug formed by particles circulating in a constrained environment . A suspension of particles (in our case they will be magnetic) flows towards a narrow channel where they tend to make a plug. This phenomenon is known to vary with the relative sizes of the particles and the neck, we will add a new tunable parameter with magnetic interactions between the beads.
Finally, additional numerical simulations of structure formation with the implementation of grain interactions are considered. This PhD project will be carried out under the joint supervision of the Porous Media Laboratory of the University of Oslo and the Physics Laboratory of the ENS de Lyon in France, respectively under the supervision of Knut Jørgen Måløy and Eirik Grude Flekkøyfoand for the University of Oslo and Mickaël Bourgoin and Stéphane Santucci for the ENS de Lyon.
 G. Dumazer, B. Sandnes, M. Ayaz, K. J. Måløy, and E. G. Flekkøy, “Frictional Fluid Dynamics and Plug Formation in Multiphase Millifluidic Flow,” Physical Review Letters, vol. 117, p. 028002, jul 2016.
 H. A. Knudsen, B. Sandnes, E. G. Flekkøy, and K. J. Måløy, “Granular labyrinth structures in confined geometries,” Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, vol. 77, no. 2, 2008.
 B. Sandnes, E. G. Flekkøy, H. A. Knudsen, K. J. Måløy, and H. See, “Patterns and flow in frictional fluid dynamics,” Nature Communications, vol. 2, no. 1, 2011.
 F. K. Eriksen, R. Toussaint, A. L. Turquet, K. J. Måløy, and E. G. Flekkøy, “Pneumatic fractures in confined granular media,” Physical Review E, vol. 95, jun 2017.
 A. J. Forsyth, S. Hutton, and M. J. Rhodes, “Effect of cohesive interparticle force on the flow characteristics of granular material,” Powder Technology, vol. 126, no. 2, pp. 150– 154, 2002.
 G. Lumay and N. Vandewalle, “Tunable random packings,” New Journal of Physics, vol. 9, 2007.
 G. Lumay and N. Vandewalle, “Controlled flow of smart powders,” Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, vol. 78, no. 6, pp. 1–4, 2008.
 A. Marin, H. Lhuissier, M. Rossi, and C. J. Kähler
Bachelor and Master of Science at École Normale Supérieure de Lyon, France.
Main courses: granular matter, soft condensed matter, active matter, fluid mechanics, turbulence, statistical mechanics.
Ferromagnetic beads sedimentation forced by an external magnetic field (4 month internship)
We studied the sedimentation of ferromagnetic beads inside a Hele-Shaw cell under the forcing of an external magnetic field. The interactions between the beads play a key role in the mechanism of sedimentation through the formation of clusters.
- 1st place at the 2017 French Physicists' Tournament [info]
- 4th place at the 2017 International Physicists' Tournament [info]