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Viscosity measurements near a critical point using a novel torsion oscillator



Robert F. Berg, Michael R. Moldover


A torsion-oscillator viscometer has been constructed for the measurement of the viscosity of fluids near both liquid-vapor and liquid-liquid critical points. This viscometer has a resolution of ±0.2% and operates at a low frequency (0.6 Hz) and a very low shear rate (0.05 Hz). Thus, it can be used closer to critical points than other viscometers before encountering the non-Newtonian phenomena associated with critical slowing down. This viscometer was used to study the viscosity anomaly near the consolute point of mixtures of methanol and cyclohexane aloug paths of constant pressure and paths of constant volume at temperatures spanning the range 10-5
International Journal of Thermophysics
Created May 1, 1986, Updated February 17, 2017