Shear-thinning effect on three-dimensional flow structure of complex fluid in optimized shape cross-slot extensional rheometer (OSCER)*

OSCER can measure the rheological properties of complex fluids at a higher extension rate than capillary breakup extensional rheometer. The shape of OSCER has been numerically optimized for a regular cross-slot under a two-dimensional flow assumption using 'upper-convected Maxwell model', however, which can only consider elastic fluid with constant viscosity. Typically, complex fluids such as polymer melts, polymer solutions, and bio-fluids including blood and DNA solution can have both elastic properties and shear-thinning viscosity simultaneously. Although both properties can affect flow structure within OSCER influencing flow instability and rheological measurement, it has rarely been investigated. In this study, we numerically study the three-dimensional flow structure of complex fluid in OSCER depending on shear-thinning properties. In conclusion, we will discuss the working conditions of OSCER depending on shear-thinning properties of complex fluids.