This formulation is recommended for the calculation of the viscosity of ordinary water in its fluid phases.
The formulation consists of a dilute-gas term that is only a function of temperature, a finite-density term as a function of temperature and density, and a near-critical term as a function of temperature and density. The near-critical term is negligible except very close to the critical point; it should be omitted for industrial use and may be omitted for other uses outside the critical region.
The region of validity the entire stable fluid region from the melting curve to 1173 K at pressures to 300 MPa, with lower maximum temperatures at higher pressures up to 1000 MPa; see the release document for details. It extrapolates in a physically reasonable way outside this region.
The development of the formulation and comparisons to available data are described in detail in a scientific article.
The Russian National Committee of IAPWS (through Moscow Power Engineering Institute) has provided online calculation pages, which may be useful in program development and verification. Note that IAPWS is not responsible for the content of these online calculation pages:
This Release is the product of the Working Group "Thermophysical Properties of Water and Steam" (TPWS) of the International Association for the Properties of Water and Steam (IAPWS).
This page updated May 29, 2018