This work presents a Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) based modelling framework for continuous tablet coating processes. To enhance the accuracy of spray modelling beyond traditional ray-tracing methods, the spray phase is represented using discrete particles within the DEM environment. This approach allows for detailed tracking of droplet-tablet interactions, enabling improved prediction of coating mass distribution. A key focus is on estimating the wetted surface area of tablets, which is critical for accurately modelling solvent drying kinetics. Drying models from literature are adapted to quantify mass transfer and predict solvent evaporation behaviour.
Model validation focuses on predicting tablet temperatures, a critical quality attribute (CQA) linked to drying performance and coating integrity. The modelling framework developed here aims to serve as a predictive tool for process design, scale-up, and optimization of continuous tablet coating operations. It also supports Quality by Design (QbD) principles and can contribute to regulatory discussions around model-based control strategies in continuous pharmaceutical manufacturing.