This work presents a comprehensive review of the evolution in modeling reactive
extrusion (REx), tracing developments from early analytical models to advanced computational
fluid dynamics (CFD) simulations. Additionally, it highlights the key challenges
and future directions in this field. Analytical models to describe the velocity profiles were
proposed in the 1950s, involving certain geometrical simplifications. However, numerical
models of melt polymeric flow in extruders have proven to be crucial for optimizing screw
design and predicting process characteristics. The state-of-the-art CFD models for single
and twin-screw extruders design address the impact of geometry (type of mixing elements
and geometrical simplifications of CFD geometries), pressure and temperature gradients,
and quantification of mixing. Despite the extensive work conducted, modeling reactive
extrusion using CFD remains challenging due to the intricate interplay of mixing, heat
transfer, chemical reactions, and non-Newtonian fluid behavior under high shear and temperature
gradients. These challenges are further intensified by the presence of multiphase
flows and the complexity of extruder geometries. Future advancements should enhance
simulation accuracy, incorporate multiphase flow models, and utilize real-time sensor data
for adaptive modeling approaches.
