@proceedings {359,
	title = {Transient regime to fluidized chimney within a granular bed by means of a 2D DEM/LBM modeling},
	journal = {IV International Conference on Particle-based Methods (PARTICLES 2015)},
	volume = {PARTICLE-BASED METHODS IV-FUNDAMENTALS AND APPLICATIONS},
	year = {2015},
	month = {sept-30-2015},
	pages = {558-566},
	publisher = {International Center for Numerical Methods in Engineering (CIMNE)},
	address = {SEP 28-30 2015 Barcelona, SPAIN},
	abstract = {<p>Beyond a given threshold, an upward fluid flow at constant flowrate, injected through a small size section, is able to generate a fluidization along a vertical chimney over the entire height of a granular assembly. Fluidization is first initiated in the immediate vicinity of the injection hole and then the fluidized zone grows gradually until reaching the upper surface of the granular packing. In this work, we present numerical results on the kinetics of chimney fluidization in an immersed granular bed produced with two-dimensional simulations coupling the Discrete Element and Lattice Boltzmann Methods (DEM-LBM). A parametric study is carried out with 11 different sets of physical parameters and analyzed based on spatio-temporal diagrams. Then a dimensional analysis allows finding general scaling laws for both threshold and growth rate of the fluidized zone by use of two dimensionless numbers, namely Reynolds and Archimedes numbers, while quite simple empirical relationships can also be proposed.</p>
},
	keywords = {DEM, Fluidization, Granular Materials, LBM},
	url = {https://hal.archives-ouvertes.fr/hal-01269325},
	author = {Jeff Ngoma and Pierre Philippe and St{\'e}phane Bonelli and Cuellar, Pablo and Jean-Yves Delenne and Farhang Radja{\"\i}},
	editor = {Onate, E and Bischoff, M and Owen, DRJ}
}
@proceedings {350,
	title = {Effect of Particle Shape non-Convexity on the Rheology of Granular Media : 3D Contact Dynamics Simulations},
	journal = {2nd International Conference on Particle-Based Methods - Fundamentals and Applications (Particles)},
	volume = {PARTICLE-BASED METHODS II: FUNDAMENTALS AND APPLICATIONS},
	year = {2012},
	month = {Apr-10-2012},
	pages = {427-434},
	address = {OCT 26-28 2011 Barcelona, SPAIN},
	abstract = {<p>We analyze the effect of particle shape non-convexity on the quasi-static behavior of granular materials by means of contact dynamics simulations. The particles are regular aggregates of four overlapping spheres described by a nonconvexity parameter depending on the relative positions of the particles. Several packings are first submitted to isotropic compression without friction. We find that, as in 2D, the solid fraction of isotropic packings increases with non-convexity up to a maximum value and then declines to be nearly equal to that of a packing composed of only spheres. It is also remarkable that the coordination number increases quickly and saturates so that the packings composed of grains with a high level of nonconvexity are looser but more strongly connected. Then, the quasi-static behavior, structural and force anisotropies are analyzed by subjecting each packing to a triaxial compression. We find that the shear strength increases with non-convexity. We show that this increase results from the presence of multiple contacts between trimers leading to enhanced frictional interlocking.</p>
},
	keywords = {force transmission, Granular Materials, non-convexity, particle shape, texture},
	url = {https://hal.archives-ouvertes.fr/hal-00686453},
	author = {Baptiste Saint-Cyr and Emilien Az{\'e}ma and Jean-Yves Delenne and Farhang Radja{\"\i} and Philippe Sornay},
	editor = {Onate, E and Owen, DRJ}
}
