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ID Project Category View Status Date Submitted Last Update 0001008 OpenFOAM Bug public 2013-09-12 17:33 2014-02-18 09:20 user19 user2 low text N/A resolved no change required 0001008: UserGuide gives wrong relation between absolute and sensible enthalpy The UserGuide (p. 181, eq. 7.1) specifies h = h_s + \sum_i c_i \Delta h_f^i where c_i is said to be the molar fraction. This is clearly wrong, and c_i should be the mass fraction instead (commonly Y_i). See e.g. Kuo, "FUNDAMENTALS OF TURBULENT AND MULTIPHASE COMBUSTION", 2012, p. 19, table 1.4) No tags attached.

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 2013-09-12 18:02 reporter   ~0002487 OpenFOAM uses internally units [J/kmol] for enthalpy, hence the mole averaging. This could probably be mentioned in the user guide. In the source code, typically upper case letters (e.g. Ha) indicate [J/kg] and lower case (e.g. ha) [J/kmol]. see also: https://github.com/OpenFOAM/OpenFOAM-2.2.x/blob/master/src/thermophysicalModels/specie/thermo/thermo/thermo.H#L226 https://github.com/OpenFOAM/OpenFOAM-2.2.x/blob/master/src/thermophysicalModels/specie/thermo/janaf/janafThermo.H#L187 user19 2013-09-13 05:16 Last edited: 2013-09-13 05:16 Ah, yes, in that case it is correct. I agree, though, that this certainly should be mentioned in the user guide. user2 2014-02-18 09:20 not a bug in OpenFOAM