Fundamental understanding of a unit process in pharmaceutical industry can be gained through predictive modeling that includes both experimental observations and analysis and mathematical modeling. This understanding is the basis of a successful implementation of PAT.

Sprays are commonly seen in the pharmaceutical industry in processes such as tablet coating, wurster bed coating, wet granulation and spray drying. All these unit operation involve some sort of spray nozzles. In this study, a fundamental look at a pressure-swirl atomizer provides understanding of the sheet formation, cone-spray patterns and subsequent breakup of the sheet into ligaments and droplets. The results are compared with experimental data and provide good visual similarities in the spray patterns and calculated cone angle from experiments.

The mathematical modeling uses a technique called Volume-of-Fluid method to model the air-water flow from a pressure-swirl atomizer. This is a fundamental model that involves no empirical or constitutive equations to model the interface. This model directly resolves the interface between air-water through first principles.

The results from this study is then used to study the influence of the input variables such as flow rates, atomization pressure on spray patterns and set up a PAT in place for spray nozzles.