Avalanches of Granular Materials

Stability, Avalanches, and Flow in Dry and Wet Granular Materials

Granular avalanches in fluids.

Three regimes of granular avalanches in fluids are put in light depending on the Stokes number St which prescribes the relative importance of grain inertia and fluid viscous effects and on the grain/fluid density ratio r. In gas (r>>1 and St>1, e.g., the dry case), the amplitude and time duration of avalanches do not depend on any fluid effect. In liquids (r approximately 1), for decreasing St,...

Rapid Granular Avalanches

Granular avalanches are one of the fundamental grain transport mechanisms in our natural environment and in many industrial grain-processing flows. In recent years significant progress has been made in describing the flow of granular avalanches over complex rigid topography. Often the fluid-like granular avalanches flow over a region of solid-like grains at which there may be erosion or deposit...

Dynamics of dry granular avalanches.

A fine analysis of the statistics of dry granular avalanches in a rotating drum setup reveals that, beyond the fluctuations, the angle at which an avalanche ends is correlated experimentally to the angle at which the avalanche starts. This correlation resulting from inertia defines an intermediate "neutral" angle that characterizes the corresponding granular pile. In addition, an intensive stud...

Continuum description of avalanches in granular media.

We develop a continuum description of partially fluidized granular flows. Our theory is based on the hydrodynamic equation for the flow coupled with the order parameter equation, which describes the transition between flowing and static components of the granular system. This theory captures important phenomenology recently observed in experiments with granular flows on rough inclined planes [A...