Modeling and computation of nonlinear rotating polymeric jets during forcespinning process

In the usual forcespinning (FS) process, a meso-scale fluid jet is forced through an orifice of a rotating spinneret, where the ambient fluid is air. This leads to the formation of a jet with a curved centerline. In this study we make use of a phenomenological viscosity model for polymeric fluid to investigate the properties of nonlinear polymeric fiber jets during FS process. We apply multi-scale and perturbation techniques to determine the governing modeling systems for such nonlinear rotating jets and their stabilities. First, we calculate numerically the expressions for the leading order nonlinear steady solutions for the jet quantities such as radius, speed, stretching rate, strain rate and trajectory versus arc length, and we determine, in particular, these quantities for different values of the parameters that represent effects due to rotation, viscosity and relaxation time. Next, we calculate the stability of the nonlinear jet versus different types of perturbations. We find that the nonlinear fiber jet flow can be stable in most cases and uncover conditions for which fiber radius reduces and the jet speed or stretching rate increases.