CFD model of slot die casting for polysulfone membranes derived from eco-friendly and bio-derived solvents in OpenFOAM

A computational fluid dynamics (CFD) model has been developed to predict the operational limits of slot die coating for polysulfone (PSU) membranes derived from eco-friendly, bio-based solvents using the open-source software OpenFOAM v2012. As a promising coating process for achieving commercial-scale fabrication of polymeric membranes, understanding the operability limits of this process is essential for producing defect-free membranes. One common approach for predicting process limits is one-dimensional calculations, but this method is not applicable to the fabrication of PSU membrane using continuous slot die coating process due to the interplay of complex factors such as boundary conditions and material properties. Due to numerous simplifications and limitations, one-dimensional calculations may lead to inaccuracies. This study presents a two-dimensional, multiphase CFD model designed to predict operating limits by constructing a casting window and validating the computational model with experimental data. The model was validated against experimental data, and previous literature, with simulated air entrainment boundaries showing less than 15% error compared to experimental findings. This level of agreement underscores the reliability of the developed model for optimizing slot die coating process.