Book contents
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 Computer simulation approaches – an overview
- 3 Structure of vibrated powders – numerical results
- 4 Collective structures in sand – the phenomenon of bridging
- 5 On angles of repose: bistability and collapse
- 6 Compaction of disordered grains in the jamming limit: sand on random graphs
- 7 Shaking a box of sand I – a simple lattice model
- 8 Shaking a box of sand II – at the jamming limit, when shape matters!
- 9 Avalanches with reorganising grains
- 10 From earthquakes to sandpiles – stick–slip motion
- 11 Coupled continuum equations: the dynamics of sandpile surfaces
- 12 Theory of rapid granular flows
- 13 The thermodynamics of granular materials
- 14 Static properties of granular materials
- References
- Index
- Plate section
1 - Introduction
Published online by Cambridge University Press: 06 October 2009
- Frontmatter
- Contents
- Preface
- 1 Introduction
- 2 Computer simulation approaches – an overview
- 3 Structure of vibrated powders – numerical results
- 4 Collective structures in sand – the phenomenon of bridging
- 5 On angles of repose: bistability and collapse
- 6 Compaction of disordered grains in the jamming limit: sand on random graphs
- 7 Shaking a box of sand I – a simple lattice model
- 8 Shaking a box of sand II – at the jamming limit, when shape matters!
- 9 Avalanches with reorganising grains
- 10 From earthquakes to sandpiles – stick–slip motion
- 11 Coupled continuum equations: the dynamics of sandpile surfaces
- 12 Theory of rapid granular flows
- 13 The thermodynamics of granular materials
- 14 Static properties of granular materials
- References
- Index
- Plate section
Summary
Sand in stasis or in motion – the image these words conjure up is one of lifelong familiarity and intuitive simplicity. Despite appearances, however, matter in the granular state combines some of the most complex aspects of known physical systems; to date, a detailed understanding of its behaviour remains elusive.
Granular media are neither completely solid-like nor completely liquid-like in their behaviour – they pack like solids, but flow like liquids. They can, like liquids, take the shape of their containing vessel, but unlike liquids, they can also adopt a variety of shapes when they are freestanding. This leads to the everyday phenomenon of the angle of repose, which is the angle that a sandpile makes with the horizontal. The angle of repose can take values between θr (the angle below which the sandpile is stationary) and θm (the angle above which avalanches spontaneously flow down the slope); in the intervening range of angles, the sandpile manifests bistability, in that it can either be at rest or have flowing down it. This avalanche flow is such that all the motion occurs in a relatively narrow boundary layer, so that granular flow is strongly non-Newtonian.
Sandpiles are not just disordered in their geometry – the shape and texture of the grains, on which physical parameters like friction and restitution depend, are also sources of disorder. These features, along with their amorphous packings, have important consequences for granular statics and dynamics.
- Type
- Chapter
- Information
- Granular Physics , pp. 1 - 17Publisher: Cambridge University PressPrint publication year: 2007