Numerical simulation of double-layer flow from tube-in-orifice spinnerets

摘要

Numerical simulations of double-layer now from tube-in-orifice spinnerets have been carried out using a differential constitutive equation. The streamline-upwinding finite element method with 4x4 sub-elements on stress components and overrelaxation method for equation of motion were used. In addition, the extrudate swell and interface shape have been experimentally observed for PVP(polyvinylpyrrolidone) aq./water system to check the validity of numerical results and to relate the flow geometry to the extrudate swell and interface shape. It was found through both numerical predictions and experiments that extrudate swell shape is strongly dependent on the location of the center tube edge in a tube-in-orifice spinneret. In particular, the minimum of the outer diameter swell was found when the center-tube edge was flush with the outer-orifice edge. These results give useful information for choosing the optimal design of a tube-in-orifice spinneret. [References: 19]