Flow Pattern and Pressure Drop in Viscoelastic Flow through Equidistant Multistage Slit

Viscoelastic flow patterns and pressure drop in single slit and equidistant multistage slit channels were investigated. In single slit channel, circularizer secondary flows were observed at the entrance, and abrupt expansion of streamlines (similar to die swell) was observed at the exit. In multistage slit channel, the circulating secondary flows at the first slit entrance were found to be the smallest compared with those at subsequent slits. These secondary flow regions depended on the first normal stress differences of the fluids. The pressure drop per slit, however, was the same through the channel. Relation between pressure drop and flow rate depended on the power law index.