Nature of the kinematic shear viscosity of water

Abstract

Nature of the kinematic shear viscosity of water ν is discussed in the work. Dependences of ν on temperature t, reduced volume $$ \tilde \upsilon $$ , and the average number of hydrogen bonds per one molecule n H (t = T/T c, $$ \tilde \upsilon $$ =υ/υc, T c and υc are critical values of temperature and reduced volume) are analyzed in detail on a liquid-vapor coexistence curve. It is shown that at T < T H (T H ≈ 310 K is the characteristic temperature of water) the formation of the kinematic shear viscosity is induced by activation. At T > T H, the shear viscosity of water is the sum of two contributions. One of them is of the same nature as in simple liquids, and another is caused by effects of hydrogen bonds. The temperature dependence of ν in this temperature region has nothing in common with exponential formulas of activation theory. The explicit form of the functional dependence of the kinematic shear viscosity on t, $$ \tilde \upsilon $$ , and n H is found and substantiated. It is shown that the value and temperature dependence of n H resulting in the experimental values of the kinematic shear viscosity of water agree well with the values corresponding to density and evaporation heat data.