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Updated: Apr 3, 2026

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Flow of wet granular materials: A numerical study
Saeed Khamseh1, Jean-Noël Roux1, François Chevoir1
1Université Paris-Est, Laboratoire Navier, 2 Allée Kepler, 77420 Champs-sur-Marne, France.
Simulations show that capillary forces in granular materials with interstitial liquid cause strain localization and affect internal friction, especially at low reduced pressures (P*). These cohesive effects significantly alter material behavior and structure, deviating from cohesionless models.
Area of Science:
- Granular physics
- Rheology
- Material science
Background:
- Dense granular assemblies with frictional spherical grains are studied under shear flow.
- Interstitial liquid introduces capillary menisci and attractive, hysteretic capillary forces.
- System behavior is governed by dimensionless parameters: inertial number (I) and reduced pressure (P*).
Purpose of the Study:
- To investigate the influence of capillary forces on the rheology and microstructure of dense granular flows.
- To analyze strain localization and macroscopic behavior under varying normal stress and saturation.
- To compare system behavior with and without capillary cohesion and hysteresis.
Main Methods:
- Numerical simulations of dense assemblies of frictional spherical grains in steady shear flow.
- Controlled normal stress (P) and inclusion of interstitial liquid (pendular regime).
- Analysis of dimensionless parameters: inertial number (I) and reduced pressure (P* = aP/(πΓ)).
Main Results:
- Systematic and enduring strain localization observed in cohesion-dominated systems (P*~0.1) at quasistatic limits.
- Homogeneous flows characterized by internal friction coefficient (μ*) and solid fraction (Φ) dependence on I and P*.
- Capillary forces significantly impact macroscopic behavior up to P* values of several units, altering structure, decreasing Φ, and inducing anisotropic fabric.
Conclusions:
- Capillary cohesion, especially with hysteresis, significantly alters granular material behavior, leading to phenomena like strain localization.
- Effective pressure and Mohr-Coulomb criteria are approximations valid only within restricted pressure ranges (P*≥1).
- Complex structural changes, including cluster formation and altered anisotropies, occur at low P*, affecting rheological functions and potentially causing shear banding.
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