A 3D numerical model for a flexible fiber motion in compressible swirling airflow

A numerical method is developed for modeling the dynamics of a flexible fiber immersed in a compressible swirling flow. The modeling approachis based on combining an Eulerian finite volume formulation for the fluidflow and a Lagrangian small-deformation formulation for the dynamics of the fiber. The fiber is modeled as a chain of beads connected through mass-less rods. The bending and twisting deformation of the fiber are represented by the displacements of the successive beads. A computational strategy is proposed for the computation of the fluid parameters at the center of discrete fiber sections. To deal with the fiber-wall interaction, a wall model is also developed. The new algorithm was verified against the experimental observations using high-speed photography. The proposed model has also been applied in a textile process to simulate the fiber motions in the two nozzles (i.e., cylindrical and diverged conical tubes, respectively) of an air-jet spinning machine, and consequently, the principle ofthe air-jet yarn formation can be demonstrated.