Convective transport in an optical fiber coating applicator for a non-Newtonian fluid

Convective transport in an optical fiber coating applicator and die system has been simulated for a non-Newtonian fluid. Low density Polyethylene (LDPE) is employed for the numerical analysis, though ultraviolet (UV) curable acrylates are commonly used, because of lack ofproperty informationfor acrylates and similar behavior of these two materials. The equations governing fluid flow and heat transfer are transformed to obtain flow in a cylindrical domain. A SIMPLE-based algorithm is used with a non-uniform grid. In contrast to the isothermal case, streamlines for the non-Newtonian fluid are found to be quite different for various fiber speeds. The temperature level in the applicator is much higher for the Newtonian case, due to the larger fluid viscositv and associated viscous dissipation. The shear near the fiber is found to be lowerfor the Newtonian fluid. As expected, the effects become larger with increasingfiber speed. A very high temperature ri. se 1. s observed in the die, regardless offiber speed. This studyfocuses on the non-Newtonian effects during the coating process, and several interesting and important features, as compared to the Newtonian case, are observed.