A thermal study of the optical fiber manufacturing process involves some of
the most challenging, and in some cases, unsolved fundamental problems in
heat transfer and fluid Mechanics. The heating stage of the process, where
the glass cylinder (preform) is heated radiantly by the cylindrical muffle
furnace, greatly influences the resultant quality of the fiber. During the
process a neckdown region is formed that is characterized by the stretching
of the glass. The two-dimensional transient equations of motion and Mass
conservation, with viscosity dependent on temperature, were solved to obtain
the velocity profiles in the glass and the shape of the neckdown region.
Axial velocity contours and the neckdown profiles were examined for various
drawing conditions. Differences between the new method presented here and
existing one-dimensional method were examined. The analysis can be used for
drawing of other materials such as metals and polymers, and the modeling is
applicable to other viscous liquids.