- Title
- Time dependence effects during conveying of particulate material: a comparison between real world behaviour and calculation theory
- Creator
- Williams, K. C.; Katterfeld, A.; Roberts, A. W.
- Relation
- 6th International Conference for Conveying and Handling of Particulate Solids with 10th ICBMH and BULKEX, 2009 (CHoPS 2009). 6th International Conference for Conveying and Handling of Particulate Solids with 10th ICBMH and BULKEX: Conference Proceedings (Brisbane, Qld 3-7 August, 2009) p. 465-471
- Relation
- http://www.chops2009.org.au
- Publisher
- Engineers Australia
- Resource Type
- conference paper
- Date
- 2009
- Description
- The mechanical behaviour of particulate material is very complex in comparison to solids, fluids and gases. It depends strongly on many properties such as particle size distribution, porosity, moisture content, overall stress and aeration. Most calculation theories are based on continuous mechanics and use widely accepted assumptions e.g. constant material properties and behaviour or plane stress conditions which lead to a steady state approach. Usually these theories incorporate empirically based factors which are usually sufficient when describing either thin layered or dispersed particulate flows. The steady state approach does not consider the real time dependant discrete behaviour of the particulate media or smaller particulate volume, which can lead to incorrect modelling of thick layered denser flows. The true physical behaviour of a particulate system is based on very many and very small interactions of the discrete particles. Each particle shows time dependent behaviour in accordance with all its neighbouring particles which subsequently affects the macroscopic behaviour of the system. In the field of bulk material handling, historically, the macroscopic behaviour is investigated. Recently, the microscopic effect of either small particulate volumes or single particle interactions can be studied by the help of new measurement equipment such as Electrical Capacitance Tomography (ECT), or through discrete element model (DEM) simulations. These investigations show a strong non-uniform behaviour of the particles for different problems. Continuum theories have also been developed to describe and predict dynamic macroscopic bulk material behaviour. The paper compares the real world behaviour of particulate materials and the classical calculation theory by the use of three examples: the pneumatic conveying of fine powders observed by ECT, the dynamic continuum modelling of particulates from a silo discharge chute and the discharge of granular material in a bucket elevators observed in experiment and simulated by DEM. The comparison of these very different problems with very different bulk material highlights the real time dependent behaviour of the particles and shows clearly the deficiencies in steady state modelling for dense layered flow regimes.
- Subject
- particulate material; mechanical behaviour; steady state approach; discrete element model; Electrical Capacitance Tomography; continuum approach; pneumatic conveying
- Identifier
- uon:8950
- Identifier
- http://hdl.handle.net/1959.13/919697
- Identifier
- ISBN:9780858259065
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