Correlation for the viscosity of liquid alkali metals

A modified Enskog equation is combined with an analytical equation of state to calculate the viscosity coefficient of liquid alkali metals. The temperature-dependent van der Waals covolume, appearing in the correlation and in the equation of state, is correlated with temperature using two scaling constants. The resulting correlation equation needs two adjustable constants, for the calculation of the viscosity coefficients of liquid alkali metals from the freezing point (about 350 K) to several hundred degrees above the boiling point (1800 K). It is shown that the present correlation well predicts the experimental liquid viscosities with an average absolute deviation of 1.7%. A comparison of the predictive ability of the present correlation with two recent theoretical methods in the literature shows that the present correlation is more accurate and covers a much wider range of temperatures and densities than those.