Granular Physics

Discrete element modeling DEM | Lattice Bolzmann modeling LBM | Continuum modeling

Discrete element modeling DEM

DEM simulations of a sheared granular layer allow to study the micromechanics of slip triggering. Friction coefficient for a reference run and perturbated run, i.e. triggered by external vibration, follows different trajectories.

Large vibration amplitude causes a clock advance of the expected slip event and significant increase of slipping contacts (dynamic friction) during the vibration interval.

Schematic representation of computational domain

Lattice Bolzmann modeling LBM

Two-dimensional graity-driven drainage in a porous material is performed using single-component multiphase LBM, as a step towards modeling porous asphalt. A fluid is rpresented by a distribution of particles. These Particles perform continuous streaming and collision over a discrete lattice mesh.

LBM of transport in different pore geometries obtained with ÁCT allows determining the permeability of segment of pore network. Neutron imaging experiments provide data for model validation.

Two Dimensional gravity-driven drainage with (a) in-line

arrangement and (b) staggered arrangement versus time

Schematic of meethods interrelations

Continuum modeling

The analysis of porous materials undergoing environmental loading or industrial processes requires that the hygric, thermal and mechanical (HTM) behavior of wood can be predicted using a fully coupled poromechanical approach. The system of coupled nonlinear equations is solved by means of finite element (FEM) method.

As an the application case, we consider friction welding of wood, a joining process due to the high frequency motion of the two wood pieces, under pressure normal to the welded plane, where the joint interface heats up. We simulate the heating of wood and validate the resulting moisture transport comparing with images acquired by neutron imaging.

HTM Moisture distribution during propagation of

a heat front: (a) experiment (b) modeling

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