Granular flow: Particle-dynamics simulations of steady flow
New research tools in the form of two- and three-dimensional discrete-particle computer models that calculate the motion of each individual grain in assemblies of hundreds of particles in steady shearing flows with either periodic or real boundaries have been developed and are being utilized to study granular flow behavior. The particle interaction models reproduce experimentally measured recoil trajectories for colliding frictional particles, including rotation effects. The steady shearing flow models agree with laboratory measurements where such data are available and they agree with theories when comparable approximations are made in the model (such as assuming frictionless and nearly elastic particles). Calculational studies with these models have shown that stresses generally vary as the square of the shear rate and the square of the particle radii and depend strongly on inelasticity and void volume and less strongly, but still significantly, on friction coefficient. Less sensitive are dependences on particle stiffness, shear-to-normal stiffness ratio and details of the transition to full sliding during frictional collisions. Laboratory measurements of the flow of glass beads cascading down through an array of horizontal cylindrical rods correlate well with gravity flow calculations of inelastic, frictional spheres falling through a similar rod array. Less elastic particles are found to cascade through the array faster than nearly elastic particles. Likewise, smaller particles are found to flow faster than large ones. Plans for extensions of the model capabilities, new boundaries, parameter studies and evaluation of new approaches for including the effects of interstitial fluids are discussed. 10 refs., 5 figs.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 7169321
- Report Number(s):
- UCRL-97505; CONF-8709155-2; ON: DE88011342
- Resource Relation:
- Conference: AR and TD solids transport contractors review meeting, Pittsburgh, PA, USA, 17 Sep 1987
- Country of Publication:
- United States
- Language:
- English
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LLNL granular solids flow project: Quarterly report, July-September 1987
Granular solids flow project: Quarterly report, July-September 1986