Abstract
Viscosity measurement of highly viscous fluids is quite difficult because they sometimes have characteristics of the non-Newtonian characteristics. The Brookfield viscometer is one of the instrument applicable to highly viscous fluid. However, even this instrument often makes failures because of the slip between the rotating prober and fluid when the viscosity is very high. Also, the results of measurement using different probers doesn't show enough agreement, when the fluid is the non-Newtonian. It seems the reason of these problems is high speed rotation of probers during the measurement. In this work, two measurement methods were proposed. In these methods, the instruments apply relatively slow deformations to evaluate the viscosity. One of the proposed method was named slump test, and the viscosity was evaluated from the deformation of fluid cylinder by its own weight. Result of this method showed qualitatively a good agreement with the Brookfield viscometer, and was applicable to the non-Newtonian fluids. The other one was named multiple shearing test. Viscous characteristics are evaluated from the shear stress obtained from multiple shear planes. This test enabled the measurement of the stress which appears before the fluid started its own deformation.
