Numerical Study of Melt Polymer Flow and Heat Transfer Characteristics in Microchannels During Melt Spinning

ABSTRACT Melt spinning of molten polymers through micro‐scale spinneret channels involves complex non‐isothermal viscoelastic flows with strong shear, extensional deformation, and coupled heat transfer. In this study, numerical simulations were performed using the commercial finite‐element software POLYFLOW to investigate the flow and heat transfer characteristics of PA6 melt in melt‐spinning microchannels. The effects of spinneret geometrical parameters (length‐to‐diameter ratio and taper angle) and process parameters (volumetric flow rate) on the pressure field, temperature field, flow behavior, and energy conversion characteristics were systematically analyzed. Flow behavior analysis through mathematical decomposition of shear and extensional rates revealed that shear deformation dominated in the melt‐spinning microchannel. Based on this, a simplified model relating viscous dissipation to shear rate was proposed, which maintained computational accuracy while reducing complexity. The analysis based on a complete energy conservation framework showed that the mechanical input energy was converted predominantly into heat through viscous dissipation, followed by elastic stored energy, while the change in kinetic energy was negligible. Furthermore, the extrudate swell behavior at the spinneret exit was analyzed with respect to the volumetric flow rate and the Weissenberg and Deborah numbers, and a normalized predictive correlation was established to provide guidance for micro‐scale melt spinning process design.