Complex Dynamics in Granular Systems

Date :From 2013-05-18 To 2013-06-21
Advisory committee :R. Behringer (Duke U., USA),C. K. Chan (Academia Sinica),M. Liu (Tubingen U, Germany),K. Lu (CAS Beijing), Aibing Yu (NSW U, Australia)
Local coordinators :Xiao-song Chen(ITP,CAS),M. Hou (IOP, CAS), M. Jiang, (Tongji U), N. Xu, (UST), P. Tong (USTHK), G. Yan (Wuhan Univ.)
International coordinators :S. Luding (Twente U,NL), H. K. Pak (Pusan U, Korea), D. Pine (NYU, USA), T. Poeschel(U Erlangen, Germany), M. Sano (U. Tokyo, Japan)
The physics of granular materials have unexpectedly become one of the hot topics in the basic research in physics communities. Even a new journal “Granular Matter” has been created for the dissemination of knowledge generated in this area. The granular materials are attractive because these materials can behave like a fluid or solid depending on the shear added onto the systems. Therefore, granular systems seem to be a new phase of matter which is governed by its dynamics. In some cases, these systems can be characterized by a steady state in which external input of energy is balanced by the internal dissipation of granular collisions. In other cases, strong inhomogeneity develops in these systems to the extent that phase separation can often occur spontaneously. Many intriguing phenomena and issues have been explored but our understandings up to date are still primordial. The following is a list of specific topics we would like to address in the program:

1) Nonlinear dynamics phenomena in granular system
Granular materials can behave both like a solid or a liquid depending on the stress applied to the system. Their flows are characterized by dissipations during collisions and external stresses needed to sustain the flows. Many intriguing patterns or dynamics can be observed in granular systems because of the nonlinear interaction between the energy input and dissipations of the system. Examples are: slip and stick dynamics, waves in granular transports, clustering, particle size segregation, shear bands, heaping, pattern formations in self-propelling particles etc. Also, particulate systems such as ER or MR fluid can be considered as granular system when the packing density of the system is high.

2) Non-equilibrium statistical mechanics
Although a molecular gas and a granular gas are both characterized by collisions, a granular gas can support phenomenon such as Maxwell’s demon or a granular clock which are not possible in an equilibrium gas. Also, the form of the velocity distribution in a granular gas is still under debate; not to mention the existence of a Fluctuation Dissipation Theorem.

3) Properties of Packed granular materials
Packed granular materials are widely used in many different areas; such as in the storage of grains in a silo, dam buildings by packed rocks etc. It is, however, still not clear how the mechanical properties of a granular packing, such as the yield stress, is related to the packed structure; especially when the grains are polydisperse. The existence of non-trivial force chains and the jamming transitions in granular systems are just two examples showing the peculiarities of packed granular materials.

4) Wet granular systems
Traditionally, only dry granular systems are studied. However, granular system with interstitial liquids occurs naturally and they can exhibit intriguing phenomena. For example, the mechanism of the ejection of interstitial liquid from wet granular system during earthquake is still unknown. Recently, particles in liquid can also be used to mimic mesoscopic systems if the system is not dominated by collisions. One can studies 2D viscosity, melting and even soft modes in such systems.

At present, most the issues mentioned above can only be understood phenomenologically. The goal of the workshop is to bring together experts in this area to discuss new directions in the explorations of the intrigue physics of granular system and their implications beyond.
National and international advisors:
R. Behringer (Duke U., USA)
C. K. Chan (Academia Sinica)
M. Liu (Tubingen U, Germany)
K. Lu (CAS Beijing)
Aibing Yu (NSW U, Australia)
Tentative program
Week One – (May 20 -24)
 Mario Liu;
 Stenfan Luding ;
 Porschel (To be confirmed)
 Takahiri Hatano
 Aibing Yu (To be confirmed)
 Kunquan Lu
 Jie Zhang
 Shunying Ji
 Ning Zheng
Week two – (May 27 -31)
 Masaki Sano
 Mahesh M. Bandi 
 Hayakawa Hisao 
 Matthias Sperl
 Kiwing To
 Jiang HR
 Jiang Yiming
 Chen Wei
Tuesday, excursion (Tianjin)
Week Three (Jun 3 -7) International Conference on Complex Dynamics of Granular System
Week Four (Jun 10 -14)
 Olafsen, JS (Jun 16)
 Hiroaki Katsuragi,
 Penger Tong (Jun 15)
 Tsai J. C.
 Chen Pei Long
 Huang JR
 Hu, Mao-Bin (Jun 15)  
 C K Chan
Week five - (Jun 17 -21)
 Mario (Talk II)
 P. Y. Lai                
 Zhang GH (Prof)
 Sun Qicheng (prof)
 Tian Guihua (prof, )
 Hong Liu (Prof)
 Hou, MY