MacroPac from Intelligensys - particle packing software publications

The following papers describe work that was done using various versions of MacroPac.

The influence of pellet size, shape and distribution on capsule filling - A preliminary evaluation of three-dimensional computer simulation using a Monte Carlo technique, R C Rowe, P York, E A Colbourn and S J Roskilly, International Journal of Pharmaceutics, 300 32-37 (2005)

A computer simulation based on a Monte Carlo technique has been developed and used to investigate the influence of pellet size, dispersity, shape and aggregation on the filling of hard shell capsules. The simulations are in general agreement with experimental observations previously reported. The results also confirm recent findings that filling is a function of pellet shape and that above an aspect ratio value of 1.2 filling reproducibility is reduced. The methodology is simple and rapid in execution allowing many computer-based experiments to be performed with minimum effort.

Note: This was performed using a modified pre-release version of MacroPac that allows rounded bottoms on a cylindrical vessel. See a picture, of a simulation of a capsule containing spherical pellets with a range of particle sizes, here.

The effect of relative particle size and deformation behaviour on the consolidation of binary powder mixtures,R C Gibb, R C Rowe, P York and P W Stott, Journal of Pharmacy and Pharmacology 57(Supplement) S63 (2005)

Research has shown that although general rules can be applied when powders are mixed and compressed into tablets, interactions can be complex and depend on physical properties such as particle size, shape, deformation behaviour and strain rate. This study is an attempt to understand the consolidation behaviour of powder mixtures. MacroPac v4 was used to generate packing simulations of binary powders to show percolation behaviour.

See a picture of a simulation of the packing of Avicel PH101 (75 vol%) and Calipharm D (25 vol%) here.

Download a copy of the poster, presented at the British Pharmaceutical Conference in Manchester in September 2005. This is nearly 4MB.

A combined finite-discrete element method for simulating pharmaceutical powder tableting, R. W. Lewis, D. T. Gethin, X. S. Yang and R. C. Rowe, International Journal for Numerical Methods in Engineering, 62 835-869 (2005)

The pharmaceutical powder and tableting process is simulated using a combined finite-discrete element method and contact dynamics for irregular-shaped particles. The particle-scale formulation and two-stage contact detection algorithm which has been developed for the proposed method enhances the overall calculation efficiency for particle interaction characteristics. The irregular particle shapes and random sizes are represented as a pseudo-particle assembly having a scaled up geometry but based on the variations of real powder particles. Our simulations show that particle size, shapes and material properties have a significant influence on the behaviour of compaction and deformation.

See a picture of a simulation here. This shows the packing of plates and spheres in a tablet die, already meshed prior to the application of a compaction force.

Heat transfer through die coatings in the aluminium die casting process, W Griffiths and K Kawai, Foundry Practice, 2419-14 (2004)

The aim of this work was to model the interfacial heat transfer mechanisms in the die casting process and in this way to obtain an estimate of the heat transfer coefficient. Its focus was to determine an equation that could be used to estimate the interfacial heat transfer coefficient in oder to provide values for use in the simulatio of casting solidification and which cold be appllied to a range fo alloys in a range of conditions. MacroPac was used to model the coating surface roughness. Good agreement was found between measured surface roughness parameters and values obtained by modelling the coating formation in this way.

The packing of thick fibres, K E Evans and M D Ferrar, J Phys D Appl. Phys 22 354-360 (1988)

Abstract
Computer simulations have been performed for the close packing of thick fibres with aspect ratios between 1 and 30. Results are presented for a range of fibre orientations including 3D random, in-plane random and aligned. It is shown that a small degree of out-of-place randomness enhances packing compared with both in-plane and 3D random orientation distributions. Thickness effects are found to be significant in determining the maximum packing fractions for aspect ratios <20. Local ordering is also a significant feature in the close packing of fibres which are otherwise random over length scales greater than the fibre length.

Note: This paper outlines the original concepts that underpin MacroPac.

Publications - MacroPac