Speaker
Description
This presentation report recent advances in the framework of the discrete element method (DEM) for multiphase granular media. Computationally efficient methods based on the DEM have been developed for a while for partially saturated materials but they have been generally limited to the pendular regime. In contrast, one hardly avoid expensive direct resolutions of 2-phase fluid dynamics problem for mixed pendular-funicular situations or even saturated regimes. Following previous developments for single-phase flow, a pore-network approach of the coupling problems is described. The geometry and movements of phases and interfaces are described on the basis of a tetrahedrization of the pore space, introducing elementary objects such as bridge, meniscus, pore body and pore throat, together with local rules of evolution [1]. As firmly established local rules are still missing on some aspects (entry capillary pressure and pore-scale pressure-saturation relations, forces on the grains, or kinetics of transfers in mixed situations) a multi-scale numerical framework is introduced, enhancing the pore-network approach with the help of direct simulations [2]. Small subsets of a granular system are extracted, in which multiphase scenario are solved using the Lattice-Boltzman method (LBM). In turns, a global problem is assembled and solved at the network scale, as illustrated by a simulated primary drainage.
References
[1] YUAN, Chao et CHAREYRE, Bruno. A pore-scale method for hydromechanical coupling in deformable granular media. Computer Methods in Applied Mechanics and Engineering, 2017, vol. 318, p. 1066-1079.
[2] CHAREYRE, Bruno, YUAN, Chao, MONTELLA, Eduard P., et al. Toward multiscale modelings of grain-fluid systems. In : EPJ Web of Conferences. EDP Sciences, 2017. p. 09027.
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