The shear behavior of granular materials immersed in a viscous fluid depends on fluid properties (viscosity, density), particle properties (size, density) and boundary conditions (shear rate, confining pressure). Using computational fluid dynamics simulations coupled with molecular dynamics for granular flow, and exploring a broad range of the values of parameters, we show that the parameter space can be reduced to a single parameter that controls the packing fraction and effective friction coefficient. This control parameter is a modified inertial number that incorporates viscous effects.

VL - 140 UR - http://www.epj-conferences.org/10.1051/epjconf/201714009044 JO - EPJ Web Conf. ER - TY - JOUR T1 - Small solar system bodies as granular systems JF - EPJ Web of Conferences Y1 - 2017 A1 - Hestroffer, Daniel A1 - Adriano Campo Bagatín A1 - Losert, Wolfgang A1 - Opsomer, Eric A1 - Sánchez, Paul A1 - Scheeres, Daniel J. A1 - Staron, Lydie A1 - Taberlet, Nicolas A1 - Yano, Hajime A1 - Eggl, Siegfried A1 - Lecomte, Charles-Edouard A1 - Murdoch, Naomi A1 - Farhang Radjaï A1 - Richardson, Derek C. A1 - Salazar, Marcos A1 - Schwartz, Stephen R. A1 - Tanga, Paolo ED - Saeid Nezamabadi ED - Luding, S. ED - Jean-Yves Delenne AB -Asteroids and other Small Solar System Bodies (SSSBs) are currently of great scientific and even industrial interest. Asteroids exist as the permanent record of the formation of the Solar System and therefore hold many clues to its understanding as a whole, as well as insights into the formation of planetary bodies. Additionally, SSSBs are being investigated in the context of impact risks for the Earth, space situational awareness and their possible industrial exploitation (asteroid mining). In all these aspects, the knowledge of the geophysical characteristics of SSSB surface and internal structure are of great importance. Given their size, constitution, and the evidence that many SSSBs are not simple monoliths, these bodies should be studied and modelled as self-gravitating granular systems in general, or as granular systems in micro-gravity environments in particular contexts. As such, the study of the geophysical characteristics of SSSBs is a multi-disciplinary effort that lies at the crossroads between Granular Mechanics, Celestial Mechanics, Soil Mechanics, Aerospace Engineering and Computer Sciences.

VL - 140 UR - http://www.epj-conferences.org/10.1051/epjconf/201714014011 JO - EPJ Web Conf. ER - TY - JOUR T1 - Strength of wet agglomerates of spherical particles: effects of friction and size distribution JF - EPJ Web of Conferences Y1 - 2017 A1 - Vo, Thanh-Trung A1 - Patrick Mutabaruka A1 - Jean-Yves Delenne A1 - Saeid Nezamabadi A1 - Farhang Radjaï ED - Luding, S. AB -We investigate the mechanical behavior of wet granular agglomerates composed of spherical particles by means of molecular dynamics simulations. The capillary cohesion force is modeled as an attraction force at the contact between two particles and expressed as an explicit function of the gap and volume of the liquid bridge. We are interested in the effect of the friction coefficient between primary particles. The agglomerates are subjected to diametrical compression tests. We find that the deformation is ductile involving particle rearrangements. However, a well-defined stress peak is observed and the peak stress is used as a measure of the compressive strength of the agglomerate. The strength increases with friction coefficient but levels off at friction coefficients above 0.4. Furthermore, the compressive strength is an increasing function of particle size span.

VL - 140 UR - http://www.epj-conferences.org/10.1051/epjconf/201714008021 JO - EPJ Web Conf. ER - TY - Generic T1 - Shear flow of dense granular suspensions by computer simulations T2 - 3rd International Symposium on Geomechanics from Micro to Macro Y1 - 2014 A1 - L. Amarsid A1 - Patrick Mutabaruka A1 - Jean-Yves Delenne ED - Kenichi Soga ED - Krishna Kumar ED - Giovanna Biscontin AB -We analyze the shear flow of dense granular materials composed of circular particles immersed in a viscous fluid by means of Molecular Dynamics simulations interfaced with the Lattice Boltzmann Method. A homogeneous flow of the suspension is obtained through periodic boundary conditions and by directly applying a confining pressure on the granular phase and shearing the fluid phase. The stead-state rheology can be described in terms of effective friction coefficient and packing fraction of the suspension as a function of the ratio of viscous shear stress to confining pressure (frictional description), on one hand, and in terms of normal and shear viscosities of the suspension as a function of the packing fraction (viscous description), on the other hand. We show that the simulation data are consistent with both descriptions and in close agreement with the corresponding scaling laws observed in recent experiments.

JF - 3rd International Symposium on Geomechanics from Micro to Macro PB - CRC Press CY - SEP 01-03-2014 Univ Cambridge, Cambridge, ENGLAND VL - Geomechanics from Micro to Macro UR - http://prodinra.inra.fr/record/369542 ER - TY - Generic T1 - Stress fields in granular solids: Effect of composition T2 - Symposium on Science and Technology of Powders and Sintered Materials (STPMF 2009) Y1 - 2011 A1 - Vincent Topin A1 - Farhang Radjaï A1 - Jean-Yves Delenne AB -We use the lattice element method to investigate stress fields at the sub-particle scale in granular solids composed of particles embedded in a cementing matrix. The stress distributions are found to be similar in 2D and 3D samples subjected to vertical loading with free lateral boundaries. We find that the number of strong forces falls off exponentially at high particle volume fractions where a percolating network of jammed particles occurs. The influence of the matrix volume fraction and particle/matrix stiffness ratio with respect to stress distribution is analyzed in 2D and 3D. We show that both decreasing the matrix volume fraction and increasing the stiffness ratio lead to increasingly broader distributions within a limit beyond which the distribution is independent of one or both of these parameters.

JF - Symposium on Science and Technology of Powders and Sintered Materials (STPMF 2009) CY - MAY 25-27 2009 Montpellier, FRANCE VL - POWDER TECHNOLOGY JO - Powder Technology ER -