PRO/II计算动力粘度为什么要有这么多方法？ 不是直接粘度除以密度就够了么？ 为什么出来这么多方法，而且计算结果还和粘度除以密度的不一样？ o(∩_∩)o谢谢 @homingpigeon kinematic viscosity [kvis] of liquid phase liquid viscosities are computed from the kinematic viscosity and the density. for purposes of this calculation, the density (sometimes in the form of specific gravity) is computed with the api method. in order to use this option, a kvis method must be declared on the method statement. a kvis option is available only with the viscosity (l) keyword. kvis methods include mixing rules that combine data for individual components to obtain a value for the bulk liquid. each kvis method can inter-convert between property values and index values. user-added methods may implement either or both conversions. see special methods for liquid viscosity in the pro/ii component and thermophysical properties reference manual for specific equations used by these methods. see special stream properties in chapter 8 of the thermodynamic data keyword manual for mixing rules used by these methods. simsci this is a perturbation expansion method that uses n-alkanes as a reference system. it divides the conversions between property values and index values into 3 regions and applies a different equation in each region. for region 1: kvis = 10000 cs. based on data at two temperatures of 100f and 210f, it was developed to be well behaved when extrapolated. usform this selects a user-defined equation-based calculation method implemented in user-added subroutine spuser.for. the method returns property values (that subsequently may be converted to index values). refer to the topic subroutine spuser in chapter 17 of the user-added subroutines user guide for a discussion of implementing these methods. index uses property values of individual components to calculate an index value for each component. it then sums the indices on a weight, molar, or liquid volume basis. usindex this selects a user-defined index method implemented in user-added subroutine cvuser.for. the method returns index values (that later may be converted tp property values). refer to the topic subroutine cvuser in chapter 17 of the user-added subroutines user guide for a discussion of implementing these methods. chevron it converts kinematic viscosities in centistokes to an index that are blended on a liquid volume basis. maxwell it converts kinematic viscosities in centistokes to an index that are blended on a liquid volume basis. slightly more complex correlation than the chevron method. refutas it converts kinematic viscosities in centistokes to an index that are blended on a liquid weight basis. similar in form to the maxwell correlation. nist23 vapor viscosities are computed using the nist23 method. gerg04 vapor viscosities are computed using the gerg04 method. 查看更多
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