Abstract
Flow through an abrupt contraction has been analyzed experimentally and theoretically through FEM simulations using the modified White–Metzner model. The results show that the ‘entrance viscosity, η ENT’ (entrance pressure drop divided by the shear rate) strongly depends on the shape of the steady extensional viscosity, the L/ D ratio of the orifice die, and it can be properly described by the newly proposed model. An ‘effective entry length correction’ is proposed and successfully tested to improve the capability of the entrance techniques to exactly predict extensional viscosity at low elongational rates. It is demonstrated that the improvements proposed in this work help to more effectively evaluate extensional rheological data from capillary measurements.
Published Version
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