Granular dynamics

below I show some movies, from discrete element simulations which dave sparks and myself have been doing on our computers. We study fault gouge and landslides, trying to understand the basics of shearing dense granular materials. So far we have found that there is a critical porosity which marks the transition between solid-like and fluid-like behaviors of granular materials. In addition we have found that transition between these two modes of shear can also be triggered by changing applied normal stress, width of the shearing layer, and velocity of shear.
Understanding shear under varying conditions has implications to understanding dynamics of landslides and earthquakes.

const porosity simulations

porosity=0.18-solid-like

porosity=0.20-transition

porosity=0.22-fluid-like

const normal stress simulations

N=1e-3

N=1e-5

N=1e-7

Landslide simulations- here we investigate flow of a layer of grains down a ramp, gravity is pointing at angle of 20 degrees.

8wide x 32high