An observation on flow patterns has shown that, when melted polyethylene liquid flows from a reservoir into a slit, the polyethylene of long relaxation time generates the circulating secondary flow near slit even at low deformation velocity.The velocity of main and circulating secondary flow has been determined by using tracers. Influences of slit width and slit length on flow behaviour have been also investigated.
The results are as follows : A significant difference has been found between the velocity of main flow and that of circulating secondary flow.The circulating flow is very slow in speed .The flow velocity at the boundary area between main and circulating secondary flow varies continuously, the velocity of the circulating flow beeing heighest at the boundary area.
The region of the circulating flows varies a little according to the slit width and slit length.Flow behaviours are, however, more influenced by deformation velocity than by slit width and slit length.
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