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To calculate area averaged species mass fraction from PDF

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Old   May 18, 2015, 02:14
Default To calculate area averaged species mass fraction from PDF
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Baradwaj B S
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Dear all,

I am having a problem in determining the mass fraction of a specie at the surface of sphere which is inside a flow domain (cylindrical) using UDF.

I have written a code for this from which the value of tot_frac will be used for mass flow rate calculation in other function.

Quote:
DEFINE_ADJUST(massfraccalc,d)
{
d=Get_Domain(1);
t=Lookup_Thread(d,ID);
begin_f_loop(f,t)
if PRINCIPAL_FACE_P(f,t)
{
d=Get_Domain(1);
t=Lookup_Thread(d,ID);
F_AREA(A,f,t);
tot_area+=NV_MAG(A);
mass_frac=mass_frac+(Pdf_Yi(c,t,3)*NV_MAG(A));
}
end_f_loop(f,t)
tot_frac=mass_frac/tot_area;
Message("Area averaged mass fraction of carbon dioxide(co2) is %e\n",tot_frac);
}

where Pdf_Yi(c,t,3) is the macro for fetching mass fraction. 3 is the specie index, i.e, in my case it is for co2.

I have tried this code for all other species (index) all seems to work fine but when I give specie index as 3, the value is always 0.00000e+0.

But the plot of area averaged mass fraction (monitor) is showing very different, it is varying every iteration.

QUESTION

Is there any problem with my UDF for area averaged mass fraction calculation?

Thanks in advance,
Bharadwaj B S
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Old   May 18, 2015, 02:16
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Baradwaj B S
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Dear all,

All required variables are defined globally outside this function.

Thanks,
Bharadwaj B S
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Old   March 7, 2016, 04:08
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志新高(Zhixin Gao)
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Dear Bharadwaj B S
maybe you have only three species, because when one use C_YI(c,t,i) macros, i=0,1,2 when there are 3 species(I am not sure if the macros you used like this or not).
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Old   March 8, 2016, 03:22
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Baradwaj B S
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Thanks for the reply. Issue was there very long back. I have used some other method to fetch mass fraction. I do not remember, sorry for that. Again huge thanks.

Regards,
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