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How to access species molecular weight in UDFs

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Old   March 12, 2009, 16:20
Default How to access species molecular weight in UDFs
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Ellen
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Hi,

I'm trying to write a User-defined mixing law for a species transport problem, and I need to use the molecular weight of species in the calculation. First I tried to use the macro C_RGAS(c,t) to get Mw: Mw = UNIVERSAL_GAS_CONSTANT/C_RGAS(c,t); but this didn't work, since C_RGAS returns 0 in my testing.

I saw that some DEFINE macros use Mw as one of its arguments, such as DEFINE_VR_RATE, but I don't know how to apply that to the macro I use (DEFINE_PROPERTY).

Could anyone please help me on how to access the molecular weight data? Thank you very much.

Ellen
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Old   March 13, 2009, 01:16
Default Re: How to access species molecular weight in UDFs
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sathees kannan
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molecular weight is a constant value. so, no need to get this as arguments. You just define like, MW_Water=18, MW_Air=29 inside your DEFINE Macro.
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Old   March 13, 2009, 12:17
Default Re: How to access species molecular weight in UDFs
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Ellen
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Thanks for replying me, Sathees. But I can't define them as constants in the program. I need to obtain these values for calculation in a species loop, I think there should be a macro for accessing the molecular weight...

Ellen
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