Understanding the effects that homogenization parameters, liquid-solid properties and
equipment have on the hydrodynamic environment in mixing vessels is of paramount
importance in pharmaceutical industry. Mixing, dissolution, and crystallization are some of the
processes that are affected by the hydrodynamic environment in the mixing vessels.
Understanding the environment enables process optimization and is essential to comply with
pharmaceutical industry guidelines. Computational fluid dynamics allows for optimization of
these processes with a reduced amount of experimental effort and offers a better insight into the
properties of the flow. In addition to process optimization, a more detailed knowledge of the
flow facilitates scale-up and scale-down processes. In the following thesis, we evaluated the
flow in a pharmaceutical mixing vessel. The flow was evaluated by comparing a computational
fluid dynamics simulation with real experimental data. We used the k-epsilon model, which in
the past has proven to be very economical and provides satisfactory results for most of the flows
used in pharmaceutical manufacturing. Based on the simulated parameters of the hydrodynamic
profiles in the mixing vessel, we made a predictive model for estimating the dissolution time of
the model substance. The model was evaluated for different mixing vessel configurations and
different mixing speeds. The tracer test showed that in most cases the mixing time can be
determined to a sufficient extent by simulation results. Noticeable differences were observed at
slower mixing speeds and greater filling volume of the mixing vessel. A more detailed
description of the hydrodynamic conditions is limited by the model used and the experimental
techniques chosen. The predictive model for the dissolution process proved to be good for the
selected combination of model material and the mixing vessel configuration. For industrial
applicability, the prediction model must be checked on the industrial or semi-industrial scale
and its general applicability should be checked with other substances that have different
dissolution kinetics.
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