Volume Viscosity in Liquid Argon at High Pressures

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Abstract
The volume viscosity in liquid argon has been calculated from ultrasonic attenuation measurements at temperatures between 85° and 145°K with pressures up to 157 kg/cm2. Measurements taken at densities from 1.06 to 1.42 g/cm3 result in values of 2.3 to 0.8 for the ratio of volume to shear viscosity. These values are compared with theoretical predictions of other investigators. It appears that the volume viscosity increases with increasing density whereas the ratio of volume-to-shear viscosity decreases. The ultrasonic attenuation rapidly increases as the temperature approaches the critical temperature. This increase in attenuation is a consequence of the change in the density and compressibility of the medium. Thus no new mechanism of dissipation is required within about 7°K below the critical temperature.