Simulation and Experimental Research on Microfluidic Coaxial Spinning Forming and Solidification Process

Microfluidic coaxial spinning has emerged as a superior technique for fabricating continuous polymer microfibers, primarily due to its exceptional tunability in precisely controlling fiber morphology and internal structures. However, understanding the complex multiphase fluid dynamics, mass transfer, and heat diffusion during the rapid phase-inversion and solidification process remains challenging. Existing computational fluid dynamics (CFD) models frequently oversimplify this phenomenon by neglecting dynamic, nonisothermal rheological transitions during solvent exchange. To bridge this gap, this study develops a comprehensive CFD framework integrating multiphase flow, species transport, and energy models to simulate continuous microfiber solidification. Crucially, a novel temperature-dependent viscosity model is introduced. The effects of flow rates, solution concentration, outer-phase viscosity, and temperature on fiber formation were systematically evaluated. Finally, the numerical framework is rigorously validated against physical experiments, offering robust theoretical guidelines for process optimization.