An optical fiber coating process in a die and applicator was numerically simulated. Coupled partial differential equations, governing the fluid flow and heat transfer, were solved on a transformed, non-uniform, staggered grid. A finite volume method, with a conjugate heat transfer model, a boundary-fitted grid transformation, and variable transport properties, was employed, with a SIMPLE-based algorithm. An isothermal case was first modeled where the effect of the Reynolds number (Re) for different geometries was studied. Different coating fluids were considered. A conjugate boundary condition at the fiber-fluid interface was employed. Regardless of fiber speed, a circulating flow was always generated in the applicator. High shear rates at the dynamic contact point suggest that air can be entrained with a fast moving fiber. It was also found that pressures at the inlet did not play a major role, whereas the thermal conditions that affect the properties of a fluid, such as viscosity, made a significant impact on both the flow and thermal fields. This work could be used to predict which parameters are critical for improving the quality of the coating, particularly its uniformity, and the production rate.
展开▼
