Consistent with the latest experimental data and the internationally recommended values for the critical parameters we published in 1987, compact and accurate correlation equations are given for the following properties on the saturation line of ordinary (light) water substance: vapor pressure, density, and enthalpy and entropy of both the saturated liquid and the saturated vapor. As an addendum to a paper by A. Saul and W. Wagner, J. Phys. Chem. Ref. Data 16, 893 (1987), this paper brings all temperature values and adjusted coefficients in all correlation equations into agreement with the International Temperature Scale of 1990 (ITS-90). The new equations form the basis of the ‘‘Revised Supplementary Release on Saturation Properties of Ordinary Water Substance’’ issued by the International Association for the Properties of Water and Steam (IAPWS). This revised release which contains all equations and coefficients adjusted with regard to the ITS-90 is the main part of this paper.
The convergence behavior of the direct simulation Monte Carlo (DSMC) method is systematically investigated for near-continuum, one-dimensional Fourier flow. An argon-like, hard-sphere gas is confined between two parallel, fully accommodating, motionless walls of unequal temperature. The simulations are performed using four variations based on Bird’s DSMC algorithm that differ in the ordering of the move, collide, and sample operations. The primary convergence metric studied is the ratio of the DSMC-calculated bulk thermal conductivity to the infinite-approximation Chapman-Enskog (CE) theoretical value, although temperature and heat flux are also considered. Ensemble, temporal, and spatial averaging are used to reduce statistical errors to levels that are small compared to the discretization errors from the time step (Δt), the cell size (Δx), and the number of computational particles per cell (Nc). The errors from these three parameters are determined using over 700 individual cases selected from the ranges 0.05<Δt∕to<1 (to is the molecular mean collision time), 0.05<Δx∕λo<1 (λo is the molecular mean free path), and 7≤Nc≤480. The infinite-particle-number (Nc→∞) convergence behavior for the thermal-conductivity ratio is found to be second-order in both time step and cell size, in good agreement with previous theoretical predictions based on Green-Kubo theory. For vanishing time step and cell size, the finite-particle-number convergence behavior is found to be O(1∕Nc) if ∼30 or more particles per cell are used. The observed convergence behavior is found to be more complicated when all three discretization parameters are finite. As discretization errors are systematically reduced, the DSMC-calculated conductivity is shown to approach the infinite-approximation CE theoretical value to within 1 part in 104.
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