(400s) Experimentally Validated Discrete Element Model to Predict Pharmaceutical Powder Flow at Different Humidity Conditions

Authors: 
Mukherjee, R., UConn
Chattoraj, S., GlaxoSmithKline
Mao, C., Genentech
Chaudhuri, B., University of Connecticut
Pharmaceutical powder flows are altered significantly based on the moisture contents and exposed humidity conditions. A Discrete Element Model (DEM) has been developed to predict the effects of humidity on powder flow, altering the cohesive forces based on granular bond numbers in three different hopper geometries. Experiments similar to the simulations are further performed for different pharmaceutical excipients at three different humidity conditions. To predict cohesive properties for powders, those did not flow under gravity; vertical vibration is introduced in both experiments and simulations. The equivalent DEM bond numbers are in good accordance with the experimental results. Pharmaceutical powders with lower moisture sorption show more variability in flow properties in comparison to cohesive powders having higher moisture contents. The equivalent DEM parameters suggest the same and are presently being implemented in a ring shear cell tester model to further quantify the flow variability at different humidity conditions.