Numerical and experimental study of damped oscillating manometers: II. Non‐Newtonian fluids

Abstract

AbstractTo test the importance of visco‐elastic properties of non‐Newtonian fluids in an oscillatory system of low frequency the dynamic characteristics of a series of non‐Newtonian fluids were studied in oscillating manometers. The manometer fluid behavior was simulated on a digital computer by numerically integrating the axial component of the equation of motion. In the simulation cone and plate steady state rheological data were represented mathematically with the Sisko rheological model. Good agreement between simulation and experimental data was obtained. This agreement implies that steady state rheological models can be utilized in the description of unsteady state non‐Newtonian systems where the characteristic period of the system is many times greater than the relaxation and retardation times of the fluid. When this characteristic period approaches these times, then rheological models which incorporate viscoelastic terms explicitly probably should be used.