MULTI-PHYSICS SIMULATION IN THE 21st CENTURY.

Email: info@physica.co.uk

[ ALUMINIUM REDUCTION CELL ]   [ CASTING & SOLIDIFICATION ]
[ ELECTRONICS APPLICATIONS ]   [ FORMING ]   [ GRANULAR FLOWS ]
[ STEEL PROCESSING ]   [ WELDING ]

Granular flows using continuum mechanics

As part of the QPM Project, PHYSICA is being used in research which aims to describe and characterise the flow of bulk solids by employing micro-mechanical parametrisations, which are derived in a Granular Dynamics environment, and link key flow parameters with granular material properties.

Novel techniques and algorithms are being developed and implemented to simulate multi-concentration granular flows and accurately describe the behaviour of the flow (i.e. segregation, degradation, caking) under different conditions (i.e. hopper filling/emptying, pneumatic conveying).

Numerical results

Simulations have clearly demonstrated the ability of the numerical model to capture key aspects of granular material behaviour, such as the change in material bulk density with height due to compression in a filled hopper and the prediction of the switch zone in the major-minor stresses following the switch in geometry for the hopper from cylinder to cone [ IMAGE ].

The incorporation of multi-concentration models, and the solution of separate transport equations with the appropriate segregation constitutive models for each of the individual material components, have enabled the simulation of percolation/segregation in mass-flow hoppers. Two cases are presented here which show the results obtain from the use of the model. In the first case a binary mixture at rest in cylindrical box (large particle size ratio, low percentage of fines in the mixture) is simulated. The percolation of fines through coarse, which remain motionless, can be seen through the animations of the bulk density [ IMAGE ] and the fines fraction [ IMAGE ]. Secondly, the emptying of a granular mixture in a mass-flow hopper was simulated. An important feature, which can be seen in the animation of the interface profile [ IMAGE ], is the dipping of the interface once the material head is in the conical section.

The model predictions have been compared to experimental data and excellent agreement between numerical simulations and experiment has been found, not only qualitatively but also quantitatively.