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 - Viscoinertial regime of immersed granular flows JF - Physical Review E Y1 - 2017 A1 - L. Amarsid A1 - Jean-Yves Delenne A1 - Patrick Mutabaruka A1 - Yann Monerie A1 - Perales, F. A1 - Farhang Radjaï AB -By means of extensive coupled molecular dynamics–lattice Boltzmann simulations, accounting for grain dynamics and subparticle resolution of the fluid phase, we analyze steady inertial granular flows sheared by a viscous fluid. We show that, for a broad range of system parameters (shear rate, confining stress, fluid viscosity, and relative fluid-grain density), the frictional strength and packing fraction can be described by a modified inertial number incorporating the fluid effect. In a dual viscous description, the effective viscosity diverges as the inverse square of the difference between the packing fraction and its jamming value, as observed in experiments. We also find that the fabric and force anisotropies extracted from the contact network are well described by the modified inertial number, thus providing clear evidence for the role of these key structural parameters in dense suspensions.

VL - 96 IS - 1 JO - Phys. Rev. E 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 -