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14 december 2018

Approved FOM programme

Number 63.
Title Physics of granular matter (PGM) 
Executive organisational unit BUW
Programme management Prof.dr. D. Lohse
Duration 2004-2013
Cost estimate M€ 4.0

The goal of this programme is to explore the physics of granular matter and to understand its behaviour.
The focus is on four key issues:
1.  What are the order parameters characterising granular matter?
2.  What conditions allow for a continuous description of granular matter?
3.  How to characterise statistical fluctuations in granular matter?
4.  What is the role of air in the dynamics of fine granular matter?

Background, relevance and implementation
Granular matter is often referred to as the fourth state of matter: Depending on the situation, granular matter can behave as a solid, a liquid, or a gas. When dry sand is poured, it acts as a fluid, while the pile on which it is poured is solid-like. When dry sand is fluidised by blowing air through it or by strong shaking, it behaves gas-like. It is the dissipative nature of the interpar­ticle interactions of granular matter which makes it behave so differently from ordinary matter.

Granular matter belongs to the class of many body systems far from equilibrium which dis­play a wide range of fascinating collective behaviour. These materials have been studied and characterised in a large number of sub-disciplines, but a general framework has been lacking so far. Recent advances in theory, numerical studies, and data-analysis techniques are begin­ning to allow us to unravel the complicated spatial structure of these materials, and the study of 'complex' matter is accelerating rapidly. Out of the various types of complex matter, granu­lar materials are particularly attractive because of their easy accessibility to experiments, while at the same time they exemplify many concepts in modern physics.

What makes the field so appealing is that many questions not only exemplify emerging con­cepts from modern physics, but also pose new basic questions: Granular materials are hetero­geneous and hysteritic, and can show jamming or transitions to glassy states. They are charac­terised by large fluctuations and form structures (such as shear bands) on scales comparable to the grain scale. Granular dynamics displays inherently dynamical phase transitions, com­plexity, and pattern formation; it is dissipative and far from equilibrium, highly nonlinear and nonlocal in time. In many cases it is even not known what the appropriate order parameters are.

Often insight from other fields has come to bear on granular problems, and interdisciplinary work will continue to be necessary to proceed further. Contributing disciplines are physics, mathematics, computation science, civil, chemical, and mechanical engineering, geophysics, and oceanography.

In the Netherlands some groups have turned their attention towards fundamental studies of granular physics in the last years. In addition, a number of physicists working in this field have recently taken faculty positions at Dutch Universities. This programme aims to build on these developments and on the strong traditions in related fields such as fluid dynamics, statistical physics, colloid science, and vortex matter, to create a substantial Dutch contribution to this increasingly important field at the forefront of non-equilibrium science.

The programme proposal and project proposals in a first round of applications was evaluated by an international peer panel in June 2003. A second round of applications was organised in 2007. Seven project proposals were approved in round 2.
The final evaluation will be based on the self-evaluation report towards the end of the programme, which will be submitted by the programme management by summer 2014.

Please find a research highlight that was achieved in 2013 within this FOM programme here.