<p>Discrete element method (DEM) modeling is a common way to
model particulate systems and processes. Since the number of particles in most
pharmaceutical processes is incredibly large, modeling these substantial magnitudes
of particles individually using DEM is not computationally reasonable. To
simplify the DEM modeling, agglomerates or groups of particles are modeled
instead. This change creates a disconnect between the real particle parameter
values and the simulated particle parameter values. Thus, efficient and
accurate calibration is needed for effective modeling. </p>
<p>The methodology proposed in this thesis
utilized a single commonly used bulk flowability measurement device, an annular
shear cell, to calibrate for these DEM parameters with the help of dimensional
analysis, design of experiments, and statistical tools. Three bulk responses
were studied from the ring shear cell: the incipient yield internal friction
angle, the critical state internal friction angle, and the bulk cohesion. The
most important DEM parameters were isolated and subjected to a dimensional
analysis to increase the generality of the results. A modified full-factorial
study was then set up using the identified dimensionless parameters. The final
calibration results were then validated using an independent flow through an orifice
test using a Flodex<sup>TM</sup>.
</p>
<p>This thesis demonstrates this
proposed calibration methodology using three different powder samples, lactose,
(hydroxypropyl) methyl
cellulose (HPMC), and ABT-089. Using the DEM simulation results and the
experimental measurements, predictive models were created for all three powder
samples. For HPMC, the calibration errors were large while using spherical
particles, so a non-spherical particle shape was introduced using the
glued-sphere model in DEM. The calibration process was repeated with simulated
non-spherical particles with an aspect ratio of two to create a new model for
HPMC. </p>
<p>The overall calibration procedure
and the three models, when validated with the Flodex simulations and
measurements, successfully predicted the Flodex results within one Flowability
index range for all three powder samples. This demonstrates that this
methodology can be used to successfully calibrate various DEM simulation
parameters.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/15149292 |
| Date | 11 August 2021 |
| Creators | Prathamesh Nilesh Sankhe (11261049) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/DEM_Parameter_Calibration_Methodology_for_Cohesive_Powders_Using_A_Ring_Shear_Tester/15149292 |
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