Parametric analysis of the transient back extrusion flow to determine instantaneous viscosity

Rotational rheometers are extremely sensitive instruments that able to provide very accurate measurements of low values different material functions, such as viscosity and viscoelastic moduli, under certain ideal flow conditions. Nevertheless, they fail in providing reliable data for the when measured at short time scales due either instrument or fluid inertia. In 1948, Bikerman [“A penetroviscometer viscous liquids,” J. Colloid Sci. 3, 75 (1948)] proposed device an measure highly (102–104 Pa · s) Newtonian fluids steady shear penetroviscometer, sample undergoes a kind flow, which is currently known back extrusion it nowadays used characterize rheological properties foodstuff this study, we perform parametric analysis (blockage ratio, initial position, velocity profile inner cylinder, fluids) determine its potential scales. Three-dimensional numerical simulations including free surface effects inertial terms allowed us limits operation. We additionally analytical expression calculate time-resolved viscosity, relating force cylinder by means geometric factor.