arXiv subjects

L. Kondic

Publications and source records attributed to L. Kondic.

20 records · Page 2Linked to original sources

arXiv2008

Signal propagation through dense granular systems

The manner in which signals propagate through dense granular systems in both space and time is not well understood. In order to learn more about this process, we carry out discrete element simulations of the system response to excitations where we control the driving frequency and wavelength independently. Fourier analysis shows that properties of the signal depend strongly on the spatial and temporal scales introduced by the perturbation. The features of the response provide a test-bed for any continuum theory attempting to predict signal properties. We illustrate this connection between micro-scale physics and macro-scale behavior by comparing the system response to a simple elastic model with damping.

cond-mat.soft↗

arXiv2002

Segregation by friction

Granular materials are known to separate by size under a variety of circumstances. Experiments presented here and elucidated by modeling and MD simulation document a new segregation mechanism, namely segregation by friction. The experiments are carried out by placing steel spheres on a horizontal plane enclosed by rectangular sidewalls, and subjecting them to horizontal shaking. Half the spheres are highly smooth; the remainder are identical to the first half, except that their surfaces have been roughened by chemical etching, giving them higher coefficients of friction. Segregation due to this difference in friction occurs, particularly when the grains have a relatively long mean free path. In the presence of an appropriately chosen small ``hill'' in the middle of the container, the grains can be made to completely segregate by friction type.

cond-mat.soft↗