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Order of species in the array of mass fraction

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Old   May 19, 2020, 10:33
Default Order of species in the array of mass fraction
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Hi everyone,

Does anyone know what is the order of species in the array of mass fractions yi or in the array mw which is passed by fluent to the UDF macro, DEFINE VR_RATE. Also does it store the mass fractions of:

1. All the species selected from the database, or

2. All the species in a mixture, or

3. All the species taking part in reactions




DEFINE VR_RATE( name,c,t,r,mw,yi,rr,rr_t)

Argument Type Description

symbol name UDF name.

cell_t c Cell index.

Thread *t Pointer to cell thread on which the volumetric reaction

rate is to be applied.

Reaction *r Pointer to data structure that represents the

current reaction.

real *mw Pointer to array of species molecular weights.

real *yi Pointer to array of the species mass fractions.

real *rr Pointer to laminar reaction rate.

real *rr_t Pointer to turbulent reaction rate.
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Old   May 19, 2020, 10:46
Default Species
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The order is same as what you see in the Species Name List in GUI. You can also use the function specie_name(Domain *d, int i) with i being the index of the specie to fetch name and compare.

Mass fractions and other relevant parameters are stored for all the species that are in the Name List, whether those are included in the reactions or not.
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Old   May 19, 2020, 13:31
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Dear vinerm,

Thank you for your reply. Although I have just one more confusion.
By GUI, you mean which one of the two: the species in the Species Panel in the mixture Properties or the species in the materials panel because both the orders are different? Pictures attached for your reference.

Also, how to write this function specie_name that you mentioned?

Did you mean a function like this:


#include "udf.h"
DEFINE_ON_DEMAND(species_list)
{
int i = -1;
char *spe_name;
Domain *d=NULL;
Material *mix_mat=NULL;
d=Get_Domain(1);
mix_mat= mixture_material(d);
mixture_species_loop_i(mix_mat,i)
{
spe_name=MIXTURE_SPECIE_NAME(mix_mat,I);
Message0("species index=%d,species name=%s\n",i,spe_name);
}
}


This code does not print anything for me
It gets compiled, but when I execute the DEFINE_ON_DEMAND, nothing prints on the console. Can you guess what might be the problem?
Attached Images
File Type: png pic_1-materials panel.PNG (68.3 KB, 4 views)
File Type: png Pic_2-Species Panel in Mixture Properties.PNG (25.1 KB, 5 views)
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Old   May 19, 2020, 15:05
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It is the one in the second image where listing is done and not the one in the materials panel.

Function requires two arguments, domain and specie index. So, specie_name(d, 0) will return h2o for your case. And there is no function called MIXTURE_SPECIE_NAME.
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Old   May 19, 2020, 15:11
Default Mixture_specie_name
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I apologize, MIXTURE_SPECIE_NAME function also exists and can be used as well. But usage is different from the function I mentioned.
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Old   May 20, 2020, 05:44
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The code below is all you need to fetch order of species in Fluent.

Code:
#include "udf.h"

DEFINE_ON_DEMAND(fpr)
{
	Domain *d = Get_Domain(1);
	int i;
	for(i = 0; i < 4; i++)
	{
		Message("Index %d is %s\n", i, specie_name(d, i));
	}
}
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