Density Dependence of the Bulk Viscosity in Argon

Abstract

The coefficient of ultrasonic attenuation in dense gaseous argon was measured as a function of frequency from 5 to 85 MHz, and as a function of density from 0.5 to 1.0 g/cm³ at −38.6°C. The attenuation was found to be in excess of that attributed to the shear viscosity and thermal conductivity and was ascribed to the existence of a significant bulk viscosity. The magnitude of the bulk viscosity was found to be less than the hard‐sphere calculation of $\frac{5}{3}$ the shear viscosity, and essentially proportional to the density squared. The results are in excellent agreement with the predictions of Gray and Rice and support the Rice—Allnatt approach to a theory of liquid transport properties.