A common research interest between all three researchers involved in this field is the rheology of dense granular materials. Experimentally, it may be studied using different devices, such as simple inclined planes, and also rheometers as used for fluids and suspensions. It has extensively been studied by grain-scale numerical simulations, as carried out in our group over the past 20 years.
The description of granular rheology in terms of internal friction laws, generalizing the classical `critical state’ of quasi statically deformed granular materials to inertial flows in the beginning of years 2000 (GdR Midi 2004, da Cruz 2005), proved very efficient, and lead to interesting applications to dense suspensions too. Recently, both experimental and simulations have been applied to wet, partially saturated granular materials, in which liquid bridges joining neighboring grains transmit attractive capillary force. Rheometric experiments, and microstructure visualization via X-ray microtomography, are illustrated in the figure below.
This ongoing research aims at the determination of macroscopic constitutive laws in connection with the characterization of flow-dependent micromorphologies of liquid distribution, contact and liquid bridge networks. It relies on both experiments and discrete numerical simulations (DEM), carried out in parallel and in synergy.