Mixing of granular systems
Team: SPACEBALLS
Francesco Ceriani
Camilla Corradi
Alessandro Fiorucci
Alessandro Marchiori
Antonio Pelucchi
Laura Zamolo
Noordwijk 29-31th March 2005
Dipartimento Chimica,
Materiali ed
Ingegneria Chimica
Giulio Natta
Milano
What is a granular system?
Granular systems
 are conglomerates of
discrete and macroscopic
particles
 behave differently from
any other aggregation
state
 have only superficial
movement
 cannot be described by
fluid dynamical laws
Great industrial interest


Mixing of granular materials is a key process in several
industrial sectors (building industry, pharmaceutical
products, human and animal feeding, detergents, chemical
products, plastics)
Processing of granular materials is considered responsible
of 10% of global energy consumption
Experimental method
Mixing phenomena were analized with two
approaches:
Experimental
Computational
The experiment
Small scale screw mixer
 Rotation provided by an electrical engine
 Alumina pallets of two different colours
 Simple and safe for the parabolic flight

Computational Model
• Modelling of the experiment
•
•
•
through a computational
code
integration of Newton’s
equations with D.E.M.
Tuning of friction and
damping constants by
comparison with
experimental data
Software: PFC3D
D.E.M. : Distinct
Element Method, useful
for the study of the
discontinuous nature of
granular systems
Why in microgravity?
Further validation of the model
 Deeper knowledge of mixing phenomena and
effects of the force of gravity
 Alternative methods (mixing in liquids) change
the physical parameters of the system
 Industrial application: product quality
improvement and energy saving
