On transport properties of hot liquid and supercritical water and their relationship to the hydrogen bonding

The dynamic viscosity η of water at temperatures along the saturation line is fitted with an expression taking into account the relative void volume, the enthalpy of vaporization, and the hydrogen bonding, the latter through the Kirkwood dipole orientation correlation parameter, g_K. A similar expression is given for the fitting of viscosity data of supercritical water, except that the explicit temperature dependence of ln η on 1/RT is now negative. The self-diffusion coefficients D of water along the saturation line up to the critical point are shown to depend on the fractions of non- and singly hydrogen-bonded water molecules. The high pressure (110 MPa) values of D of supercritical water are a smooth extension of the values for lower temperature water at the same pressure.