Ray Casting DEM Simulation Data to Characterize the Spray Coating of Superquadric Particles
Typ
Examensarbete för masterexamen
Program
Engineering mathematics and computational science (MPENM), MSc
Publicerad
2020
Författare
Andersson, Pontus
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Drum spray coating of tablets is a common unit operation in the pharmaceutical production
process. Increasingly, the Discrete Element Method (DEM) is being used to
study and optimize this process in order to improve the resulting tablet coating uniformity.
Multi-spheres are a popular approach to shape approximation in DEM, but
have been shown to be insufficient at modeling the bulk kinematics of certain tablet
shapes. This work develops a method that enables the use of superquadrics in DEM
to study inter- and intra-tablet coating variability. Specifically, a standalone C++
program is developed that models the spray by casting rays on data exported from
DEM simulations. Acceleration techniques like spatial subdivision and bounding
volumes are used to reduce the runtime, and an efficient intra-particle representation
is developed and used to compute the intra-tablet coating variability. The final
implementation is capable of processing a 180 second simulation containing 2 million
tablets in just a few hours on a conventional desktop computer. Key parameters
of the implementation are studied through benchmarks and suggestions of suitable
values are made. The tool is finally used to show that the blockiness of the DEM
shape representation has a significant impact on intra-tablet coating variability, but
further studies are needed to better understand this effect.
Beskrivning
Ämne/nyckelord
Coating variability, DEM, Superquadric, Shape approximation, Ray casting, Acceleration techniques