Viscosity of fluid nitrogen to pressures of 10 GPa.

Shear viscosities of supercritical nitrogen have been measured in the high-pressure diamond-anvil cell, to 673 K and pressures in excess of 10 GPa, using a rolling-sphere technique. The entire set of data, along with lower pressure data from the literature, can be fit to a two-parameter expression in reduced viscosity and reduced residual entropy. The fit spans densities from the dilute gas to 5x the critical density, and two orders magnitude in temperature and in viscosity, with a maximum deviation of 20%.

Viscosity of methane to 6 GPa and 673 K.

A rolling-sphere technique has been used to measure shear viscosities of (supercritical) fluid methane in a diamond-anvil cell between temperatures of 294 and 673 K, up to a pressure of 6 GPa. A correlation between a reduced viscosity and reduced residual entropy is shown to give a good account of much of the extant data, both from this study and the literature.

Viscosity of carbon dioxide measured to a pressure of 8 GPa and temperature of 673 K.

Shear viscosities of supercritical carbon dioxide have been measured to 673 K and 8 GPa (80 kbar). Measurements were made in a diamond-anvil cell with a rolling-ball technique. Individual isotherms are well fit by a modified free-volume equation.

Viscosity of nitrogen measured to pressures of 7 GPa and temperatures of 573 K.

Shear viscosities of supercritical nitrogen have been measured to 573 K and 7 GPa (70 kbars). Measurements were made in a diamond-anvil cell with a rolling-ball technique. Individual isotherms are well fitted by a modified Doolittle equation.

Viscosity of water measured to pressures of 6 GPa and temperatures of 300 degrees C.

Shear viscosities of fluid water have been measured to 300 degrees C and 6 GPa (60 kbar). Measurements were made in a diamond-anvil cell with a rolling-ball technique. Enskog's equation for viscosity, coupled with an ad hoc assumption that increased collision rates are due to an "excluded volume", yield excellent matches to the data at temperatures of 100 degrees C and over, without any freely variable parameter.