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why does fluent use species mass fraction as default inlet condition? |
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May 11, 2020, 11:19 |
why does fluent use species mass fraction as default inlet condition?
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#1 |
Senior Member
Weiqiang Liu
Join Date: Feb 2018
Posts: 278
Rep Power: 9 |
hi all,
I am trying to set species inlet condition of a combustor according to fuel equivalence ratio mentioned in the paper. I am wondering why does fluent use mass fraction as default inlet condition instead of mole fraction? Because it would be more convenient to use mole fraction of species to set equivalence ratio of fuels. Best regards Weiqiang |
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May 11, 2020, 11:43 |
Mole Fractions
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#2 |
Senior Member
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Fluent provides option to use mole fraction instead of mass fraction; if you are using old version then it will only have mass fraction. It's primarily for legacy reason but also because primary users of Fluent in the industry do not use mole fractions but mass fractions.
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Regards, Vinerm PM to be used if and only if you do not want something to be shared publicly. PM is considered to be of the least priority. |
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May 11, 2020, 22:48 |
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#3 | |
Senior Member
Weiqiang Liu
Join Date: Feb 2018
Posts: 278
Rep Power: 9 |
Quote:
Thanks very much for your answer! Best regards Weiqiang |
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May 12, 2020, 05:14 |
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#4 |
Senior Member
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,754
Rep Power: 66 |
The governing equations for the species transport equation are written in mass fraction. Since that's the primitive variable that the solver operates on, naturally it should default to mass fraction.
It's way easier to build transport equations this way valid for compressible flows because the advective flux is the mass-flux. |
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May 12, 2020, 05:24 |
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#5 | |
Senior Member
Weiqiang Liu
Join Date: Feb 2018
Posts: 278
Rep Power: 9 |
Quote:
Best regards Weiqiang |
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Tags |
equivalence ratio, mass fraction, mole fraction |
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