Review of the CFD Simulations of High-Viscosity Fluid Mixing in Mixers

High-viscosity fluid mixing is a critical unit operation in chemical engineering and polymer processing. Its efficiency and uniformity directly determine product quality and production costs. This paper reviews the mixing mechanisms of high-viscosity fluids, which rely on laminar stretching and folding rather than turbulent eddies, and summarizes the corresponding CFD models and constitutive equations of fluid. It also introduces different methods to reduce numerical diffusion and summarizes high-viscosity mixers. Current challenges, such as numerical diffusion in laminar simulations and the high Weissenberg number problem, are discussed. The application of machine learning in CFD simulations is considered a prospective method to enhance the accuracy and efficiency of simulations involving high-viscosity fluid mixing.