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IAPWS_IF97 functional form with no slip



18 Mar 2012 (Updated )

Water and steam properties and derivatives based on the IAPWS IF97. Functional form. No slip.

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IAPWS_IF97(FUN,IN1,IN2) is 27 functions of water properties and derivatives, based on the International Association on Properties of Water and Steam (http://www.iapws.org). Thermodynamic, hydrodynamic and non-linear modeling often requires thermodynamic derivatives, therefore IAPWS_IF97 can calculate most property derivates as functions of pressure and enthalpy, e.g.: dT/dp_ph, cp_ph, dv/dp_ph and dv/dh_ph. Since modeling often involves multiple dimensions that are discretized or meshed to form a set of either finite-difference or finite-element equations, IAPWS_IF97 is vectorized even across regions (subcooled/compressed-liquid, saturated, superheated and supercritical). For arrays is an order of magnitude faster than XSteam and is multithreaded if your computer is capable.

This is the functional form. I will submit a class & package versions definition soon, that also offer slip correction using Zivi's correlation (1964) for 2-phase flow.

Please report bugs here or at Github:

Reference Documents:
Industrial Formulation 1997 (IF97-Rev, IAPWS-IF97), IAPWS-IF97-S01, IAPWS-IF97-S03rev, IAPWS-IF97-S04, IAPWS-IF97-S05, Revised Advisory Note No. 3 Thermodynamic Derivatives from IAPWS Formulations 2008, Release on the IAPWS Formulation 2008 for the Viscosity of Ordinary Water Substance, 2008 Revised Release on the IAPWS Formulation 1985 for the Thermal Conductivity of Ordinary Water Substance.

Thermal Conductivity [W/m/K]:
    'k_pT', 'k_ph'
Viscosity [Pa*s]:
    'mu_pT', 'mu_ph', 'dmudh_ph', 'dmudp_ph'
Enthalpy [kJ/kg]:
    'h_pT', 'hL_p', 'hV_p', 'dhLdp_p', 'dhVdp_p'
Specific Volume [m^3/kg]:
    'v_pT', 'v_ph', 'vL_p', 'vV_p', 'dvdp_ph', 'dvdh_ph'
Temperature [K]:
    'T_ph', 'dTdp_ph', 'cp_ph'
Saturation Pressure [MPa] and Temperature [K]:
    'psat_T', 'Tsat_p', 'dTsatdpsat_p'


X Steam, Thermodynamic Properties Of Water And Steam. inspired this file.

This file inspired Water And Steam Refractive Index and A Simple Finite Volume Solver For Matlab.

Required Products MATLAB
MATLAB release MATLAB 7.5 (R2007b)
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Comments and Ratings (9)
19 Jun 2014 Ehsan  
17 Oct 2013 Zoe

fast nice... parallel computing :)

14 Oct 2013 Mark Mikofski

The documentation is online here:

13 Dec 2012 Thomas Clark

Nice vectorisation, thank you for this Mark.

15 May 2012 Peter Sugimura  
26 Mar 2012 Mark Mikofski

until implemented, quality can be calculated from either enthalpy or specific volume and from either psat or Tsat as follows:

x_ph = @(p,h)(h - hL_p(p))./(hV_p(p) - hL_p(p))

then use x = x_ph(p,h)


x_hT = @(h,T)(h - hL_p(psat_T(T)))./(hV_p(psat_T(T)) - hL_p(psat_T(T)))

then use x = x_hT(h,T)

and the very similar for specific volume:

x_pv = @(p,v)(v - vL_p(p))./(vV_p(p) - vL_p(p))

then use x = x_pv(p,v)


x_vT = @(v,T)(v - vL_p(psat_T(T)))./(vV_p(psat_T(T)) - vL_p(psat_T(T)))

then use x = x_vT(h,T)

26 Mar 2012 Mark Mikofski

Great suggestions Jonathan. I have added them to the issues list on Github here:
Also, I cp is available as a function of p & h (but not p & T as you pointed out), if that would suit your needs.

26 Mar 2012 Jonathan Currie

Good implementation and the vectorization works really well. However would suggest adding:

- Entropy calculations
- Cp, Cv calculations as a function of P,T (not constrained by region)
- Inverse calculations for P
- Quality calculations
- More property pairings (e.g. P,T, P,S, P,H, H,S)
- Customizable units?

Not sure on the implementation question. I've always found classes too slow, there seems to be a bit of getting started overhead in every method call.

22 Mar 2012 Mark Mikofski

I've thought of a couple of other ways to present this code:
1. as a "+folder package", each function in it's own file; use namespace or import to use functions; e.g. IAPWS_IF.h_pT(0.1,298)
2. a @class folder, consolidate constants as hidden constant properties, functions as methods or static methods, method to set slip if slip is desired for 2-phase flow
3. "+folder package" for class, same as #2 but in a package for import.
Each has pros and cons. What works best for users?

19 Mar 2012

revise/format description, add more tags

23 Mar 2012

add link to github

23 Mar 2012

show units, categorize and format functions

26 Mar 2012

acknowledge Magnus Holmgren's XSteam

14 Oct 2013

add quality, update help, add assertions

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