Patterned Nonaffine Motion in Granular Media

Nonaffine correlations in random elastic media.

Materials characterized by spatially homogeneous elastic moduli undergo affine distortions when subjected to external stress at their boundaries, i.e., their displacements from a uniform reference state grow linearly with position , and their strains are spatially constant. Many materials, including all macroscopically isotropic amorphous ones, have elastic moduli that vary randomly with positi...

Multilaminate Elastoplastic Model for Granular Media

A multilaminate based model capable of predicting the behavior of granular material on the basis of sliding mechanisms and elastic behavior of particles is presented. The capability of the model to predict the behavior of sand under arbitrary stress paths is examined. The influences of rotation of the direction of principal stress axes and induced anisotropy are included in a rational way witho...

Swimming in granular media.

A class of reptiles known as sand swimmers adapts to hot environments by submerging beneath desert sands during the day and so provide a unique probe into the dynamics of intruders in granular beds. To understand the mechanism for swimming in an otherwise solid bed, we study a simple model of periodic contraction and extension of large intruders in a granular bed. Using an event-driven simulati...

Interference Lithography for Patterned Media

Capillary fracturing in granular media.

We study the displacement of immiscible fluids in deformable, noncohesive granular media. Experimentally, we inject air into a thin bed of water-saturated glass beads and observe the invasion morphology. The control parameters are the injection rate, the bead size, and the confining stress. We identify three invasion regimes: capillary fingering, viscous fingering, and "capillary fracturing," w...