During different industrial melt spinning processes, polymer resin is melted in an extruder and flows to the individual capillaries of a spinning head via a distributor. Generally, the cross-section of the polymer melt flow must be expanded from that of the inflow tube to the considerably larger cross-section of the spinning plate with its capillaries.
The flow velocities are decreasing here; therefore, dead zones may arise especially in the vicinity of the walls, where the polymer degrades and is accumulated at the walls. An appropriate measure for the flow velocity in the vicinity of the walls is the so-called wall shear stress, which can be influenced specifically by modifications of the flow area. However, the dependences are not local and are very complex, so that a modification does only make sense on the basis of a mathematical optimization process. An optimization method for such problems has been developed at the ITWM on the basis of appropriate criteria.