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.

}, doi = {10.1051/epjconf/201714009044}, url = {http://www.epj-conferences.org/10.1051/epjconf/201714009044}, author = {L. Amarsid and Jean-Yves Delenne and Patrick Mutabaruka and Yann Monerie and Perales, F. and Farhang Radja{\"\i}}, editor = {Saeid Nezamabadi and Luding, S.} } @article {263, title = {Viscoinertial regime of immersed granular flows}, journal = {Physical Review E}, volume = {96}, year = {2017}, month = {Oct-10-2017}, pages = {Article Number: 012901}, abstract = {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.

}, issn = {2470-0045}, doi = {10.1103/PhysRevE.96.012901}, author = {L. Amarsid and Jean-Yves Delenne and Patrick Mutabaruka and Yann Monerie and Perales, F. and Farhang Radja{\"\i}} } @proceedings {366, title = {AIP Conference ProceedingsTumbling sandpiles in a fluid}, journal = {7th International Conference on Micromechanics of Granular Media (Powders and Grains)}, volume = {Book Series: AIP Conference Proceedings POWDERS AND GRAINS 2013}, year = {2013}, month = {Jul-2013}, pages = {662-665}, publisher = {AIP}, address = {JUL 08-12 2013 Sydney, AUSTRALIA}, abstract = {By means of contact dynamics simulations interfaced with computational fluid dynamics, we analyze the effect of a suspending fluid on the dynamics of collapse and spread of a granular column. We find that the runout distance increases as a power law with the aspect ratio of the column and, for a given aspect ratio, it may be the same in the grain-inertial and fluid-inertial regimes but with considerably longer duration in the latter case. We show that, in both viscous and fluid-inertial regimes, this behavior results from compensation between two effects of the fluid: 1) reduction of the kinetic energy during collapse and 2) enhancement of the flow by lubrication during spread.

}, doi = {10.1063/1.4812018}, author = {Farhang Radja{\"\i} and Vincent Topin and Perales, F. and Yann Monerie}, editor = {Yu, A and Dong, K and Yang, R} } @proceedings {370, title = {GRANULAR SLUMPING IN A FLUID : FOCUS ON RUNOUT DISTANCES}, journal = {3rd International Conference on Particle-based Methods}, volume = {PARTICLE-BASED METHODS III: FUNDAMENTALS AND APPLICATIONS}, year = {2013}, month = {Sept-2013}, pages = {115-123}, address = {SEP 18-20 2013 Stuttgart, GERMANY}, author = {Vincent Topin and Yann Monerie and Perales, F.}, editor = {Bischoff, M and Ramm, E and Onate, E} } @article {294, title = {Collapse Dynamics and Runout of Dense Granular Materials in a Fluid}, journal = {Physical Review Letters}, volume = {109}, year = {2012}, month = {Nov-02-2012}, pages = {Article Number: 188001}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.109.188001}, author = {Vincent Topin and Yann Monerie and Perales, F. and Farhang Radja{\"\i}} } @article {295, title = {Tensile strength and fracture of cemented granular aggregates}, journal = {The European Physical Journal E}, volume = {35}, year = {2012}, month = {Nov-2012}, pages = { Article Number: 117}, abstract = {Cemented granular aggregates include a broad class of geomaterials such as sedimentary rocks and some biomaterials such as the wheat endosperm. We present a 3D lattice element method for the simulation of such materials, modeled as a jammed assembly of particles bound together by a matrix partially filling the interstitial space. From extensive simulation data, we analyze the mechanical properties of aggregates subjected to tensile loading as a function of matrix volume fraction and particle-matrix adhesion. We observe a linear elastic behavior followed by a brutal failure along a fracture surface. The effective stiffness before failure increases almost linearly with the matrix volume fraction. We show that the tensile strength of the aggregates increases with both the increasing tensile strength at the particle-matrix interface and decreasing stress concentration as a function of matrix volume fraction. The proportion of broken bonds in the particle phase reveals a range of values of the particle-matrix adhesion and matrix volume fraction for which the cracks bypass the particles and hence no particle damage occurs. This limit is shown to depend on the relative toughness of the particle-matrix interface with respect to the particles.

}, issn = {1292-8941}, doi = {10.1140/epje/i2012-12117-7}, author = {Rafik Aff{\`e}s and Jean-Yves Delenne and Yann Monerie and Farhang Radja{\"\i} and Vincent Topin} } @proceedings {352, title = {Modeling Porous Granular Aggregates}, journal = {9th International Workshop on Buifurcation and Degradation in Geomaterials (IWBDG 2011)}, volume = {Springer Series in Geomechanics and Geoengineering - ADVANCES IN BIFURCATION AND DEGRADATION IN GEOMATERIALS}, year = {2011}, month = {May-28-2011}, pages = {249 - 254}, publisher = {Springer Netherlands}, address = {MAY 23-26 2011 Porquerolles, FRANCE}, abstract = {We rely on 3D simulations based on the Lattice Element Method (LEM) to analyze the failure of porous granular aggregates under tensile loading. We investigate crack growth by considering the number of broken bonds in the particle phase as a function of the matrix volume fraction and particle-matrix adhesion. Three regimes are evidenced, corresponding to no particle damage, particle abrasion and particle fragmentation, respectively. We also show that the probability density of strong stresses falls off exponentially at high particle volume fractions where a percolating network of jammed particles occurs. Decreasing the matrix volume fraction leads to increasingly broader stress distribution and hence a higher stress concentration. Our findings are in agreement with 2D results previously reported in the literature.

}, isbn = {978-94-007-1420-5}, issn = {1866-8755}, doi = {10.1007/978-94-007-1421-2_32}, author = {Rafik Aff{\`e}s and Vincent Topin and Jean-Yves Delenne and Yann Monerie}, editor = {St{\'e}phane Bonelli and Dascalu, Cristian and Fran{\c c}ois Nicot} }