louisont

• Thorens, Louison; Rodriguez, Solenn; Taberlet, Nicolas; Bourgoin, Mickael; Måløy, Knut Jørgen & Santucci, Stephane (2026). Hybrid magnetic Janssen effect arising from percolating ferromagnetic grain networks. Soft Matter. ISSN 1744-683X. doi: 10.1039/d6sm00069j. Fulltekst i vitenarkiv
• Thorens, Louison; Måløy, Knut Jørgen; Flekkøy, Eirik Grude; Sandnes, Bjørnar; Bourgoin, Mickaël & Santucci, Stephane F A (2023). Capillary washboarding during slow drainage of a frictional fluid. Soft Matter. ISSN 1744-683X. doi: 10.1039/d3sm00717k. Fulltekst i vitenarkiv Vis sammendrag

  Numerous natural and industrial processes involve the mixed displacement of liquids, gases and granular materials through confining structures. However, understanding such three-phase flows remains a formidable challenge, despite their tremendous economic and environmental impact. To unveil the complex interplay of capillary and granular stresses in such flows, we consider here a model configuration where a frictional fluid (an immersed sedimented granular layer) is slowly drained out of a horizontal capillary. Analyzing how liquid/air menisci displace particles from such granular beds, we reveal various drainage patterns, notably the periodic formation of dunes, analogous to road washboard instability. Considering the competitive role of friction and capillarity, a 2D theoretical approach supported by numerical simulations of a meniscus bulldozing a front of particles provides quantitative criteria for the emergence of those dunes. A key element is the strong increase of the frictional forces, as the bulldozed particles accumulate and bend the meniscus horizontally. Interestingly, this frictional enhancement with the attack angle is also crucial in small-legged animals' locomotion over granular media.

• Thorens, Louison; Måløy, Knut Jørgen; Santucci, Stephane & Bourgoin, Mickael (2021). Magnetic Janssen effect. Nature Communications. 12. doi: 10.1038/s41467-021-22722-y. Fulltekst i vitenarkiv Vis sammendrag

  Abstract A pile of grains, even when at rest in a silo, can display fascinating properties. One of the most celebrated is the Janssen effect, named after the pioneering engineer who explained the pressure saturation at the bottom of a container filled with corn. This surprising behavior arises because of frictional interactions between the grains through a disordered network of contacts, and the vessel lateral walls, which partially support the weight of the column, decreasing its apparent mass. Here, we demonstrate control over frictional interactions using ferromagnetic grains and an external magnetic field. We show that the anisotropic pairwise interactions between magnetized grains result in a radial force along the walls, whose amplitude and direction is fully determined by the applied magnetic field. Such magnetic Janssen effect allows for the fine tuning of the granular column apparent mass. Our findings pave the way towards the design of functional jammed materials in confined geometries, via a further control of both their static and dynamic properties.

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• Thorens, Louison (2021). Unstable Drainage of Frictional Fluids and Magnetic Control of the Mechanical Behavior of Confined Granular Media. Universitetet i Oslo. Fulltekst i vitenarkiv

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