A Three-Dimensional Multiphase Simulation of the Fiber Spiral Motion Under a Melt-Blowing Swirl Die

Melt blowing is a conventional process for the production of nonwoven fabrics in which high-speed jets of hot air are blown onto a polymer melt to produce random fibers, which are then collected on a conveyor belt to form a web-like product. The polymer melt usually consists of a single species like polypropylene, but hot-melt adhesives are also processed in the same manner. The latter are designed to be extremely cohesive and often highly elastic, preventing fiber breakup and favoring an ordered deposition on the substrate. In this study, we model the molten adhesive as a non-Newtonian fluid and calculate its trajectory under a melt-blowing swirl die in a three-dimensional multiphase CFD simulation. For the first time, we successfully replicate the spiral path that other authors have observed experimentally. We have also performed our own measurements to validate the model, finding that it reproduces the general trends of the response to variation in processing conditions but lacks quantitative predictive power. The swirl die studied here has a different geometry than those used by other authors, but is also common in industrial applications and known to induce a similar motion on the polymer fiber.