Stagnation Flow Extensional Viscosity Measurement Using Inverse Methods

This paper presents a novel approach to extensional viscosity measurement. A pressure drop technique in using stagnation point flow in a T- junction was implemented to obtain viscoelastic characteristics of a complex fluid. The stagnation point flow generates a non-homogeneous flow field which induces a range of extensional rates along the back wall of the channel. This geometry creates an information rich flow field that yields the whole extensional viscosity response curve in one experiment. A CFD model was created to predict flow field statistics of the flow. An inverse method was tested in order to assess constitutive parameters of a fluid of interest. Potentially this method could be used in development of a new extensional rheometer as an on-line and in-line controlling device in many industrial processes.