Available at: http://digitalcommons.calpoly.edu/theses/1331
Date of Award
MS in Mechanical Engineering
A single use pharmaceutical mixer was analyzed for performance with various system configurations using Computational Fluid Dynamics. The analysis was conducted across a range of oscillation frequencies and liquid fill levels within a fully sealed mixing tank to determine the rate of fluid homogenization, liquid shear, velocity profiles and force application utilizing a single and dual mixer flat plate head configuration. These characteristics are useful for predicting the expected mixing time of a fluid and how much fluid shear is acting on protein cultures that are intended to be grown in the mixing vessel. General trends show that larger fill volumes take longer to homogenize, though as the volume increases the time for homogenization increases by a smaller factor, showing increased mixing efficiency at larger volumes. Furthermore, higher frequency oscillations yield little benefit for homogenization time with only 20% gains when increasing the frequency from 6 Hz to 12 Hz. The shear analysis shows that higher oscillation frequencies increase the wall shear acting on the fluid by an exponential amount, indicating that the higher frequencies are counterproductive toward protein production. Velocity analysis shows that zones of stagnation exist within the mixing system that slow fluid homogenization and exist at the same locations regardless of mixer oscillation frequency. Force application on the mixer head was analyzed to compare to analytical hand calculations to provide a basis of model validation, ultimately showing congruency and that the fluid flow is primarily pressure driven.