Granular Matter

(supported by NSF Grants DMS 0605857 and 0835611; NASA Grant NNC04GA98G; DTRA Grant  1-10-1-0021)

[See below for selected publications]

Recent colaborators:

Granular materials are poorly understood at a fundamental level. While there is a number of continuum models, usually based on elastoplastic type of constitutive relations, it is still very difficult to understand some basic features of granular materials based on continuum picture alone. One of the reasons are fluctuations, whose which are not necessary small, as it is emphasized by this picture of stress chains in slowly sheared granular system.

Molecular dynamics / Discrete element simulations appear to be a natural approach to gain better insight into these systems. During last few years, I have been developing 2D and 3D MD simulations with the goal of explaining some basic features of statics and dynamics of granular materials. This research has developed in few directions; some of these are listed below and in the linked pages.

Evolution of force networks in dense granular materials.   This direction of research focuses on the analysis of force networks carried out by emplying the techniques based on computational homology in collaboration with the Rutgers group headed by K. Mischaikow.  After carrying out extensive research of granular systems exposed to compression (research publications are linked here, we are now focusing on the evolution of force networks in sheared granular systems.  

More information, as well as animations of force networks of sheared systems under different protocols can be found at the web page of Lenka Kovalcinova, PhD candidate at NJIT.

Force and Energy transport in dense granular materials.  This large scale project concentrates on propagation of imposed perturbation through dense granular systems.  Both molecular dynamics simulations and continuum models are being developed.  In collaboration with R.P. Behringer, Duke, and M.D. Shattuck, CCNY.  More details about this project are available here.

Dynamics of dense granular mater under variable gravity conditions.  A significant part of this project concentrates on a sheared granular system in Couette geometry. This research, sponsored by NASA Microgravity Program, is performed in close collaboration with the granular group at Duke University lead by R. P. Behringer. The figure below shows an example of the `force chains' that appear as granular particles experience as they are being sheared.

More information about this research project can be found here.

Selected recent publications on granular materials:

(see here for the complete list).