[Priyank Mehta]

Hello I want to make UDF for density in which density will depend on temperature , pressure and also on species..here I am attaching my density formula and my UDF ...Please help thank you in adavnce

[Priyank Mehta]

Originally Posted by Priyank Mehta

Hello I want to make UDF for density in which density will depend on temperature , pressure and also on species..here I am attaching my density formula and my UDF ...Please help thank you in adavnce

#include "udf.h"

#include "mem.h"

#include " materials.h"

DEFINE_PROPERTY(dust, c, t)

{

real rho_s,rho_g,alphav,dT,dP,totaly,al,o2,al2,n2,Dust_ rho;

rho_g=1.225;

rho_s=2700;

alphav=0.0001859;

totaly=0;

dT=C_T(c,t);

dP=C_P(c,t);



mixture_species_loop (m,sp,i)

al=C_YI(c,t,1);

o2=C_YI(c,t,2);

al2=C_YI(c,t,3);

n2=C_YI(c,t,4);





totaly=(al/26.9815)+(o2/31.9988)+(al2/101.96)+(n2/28.0134);



dust_rho = (1+alphav*((rho_s/rho_g)-1))*(dP/(dT*totaly*8314.34));



return dust_rho;





}

[Priyank Mehta]

sen2.PNG

Here I am attaching my required density which is a function of Pressure, Temperature and species mass fraction.


Hoping for your reply thank you

[pakk]

So, you want a UDF, and you have a UDF. What is the problem that you want us to solve?

[Priyank Mehta]

Originally Posted by pakk

So, you want a UDF, and you have a UDF. What is the problem that you want us to solve?

Thank you for your reply....This UDF is not working.... I am getting many errors..like structure reference not implemented...So write now I am confuse with two things...1. I have to interpret or compile this code.
2. The probable reason of my error is extracting mass fraction...


Hoping for your reply
Thank you

[pakk]

If you want help, be specific! Don't let us guess what you need help with!

So something is wrong with your UDF. You get errors. But be specific: which errors??? Show them here! If there are too many errors to show, the first ones are usually the most relevant.

And about compiling or interpreting: if possible, compile.

[Priyank Mehta]

Originally Posted by pakk

If you want help, be specific! Don't let us guess what you need help with!

So something is wrong with your UDF. You get errors. But be specific: which errors??? Show them here! If there are too many errors to show, the first ones are usually the most relevant.

And about compiling or interpreting: if possible, compile.

Thank you for your response...And sorry for the inconvenience...
1. While interpret...It is showing structure reference not implemented...
2. While compile..It is showing the system can not find the path specified...

This are the problem related to the UDF error..

Other then this I am facing problem while writing a code.
1. I don't understand how to extract value for the mass fraction..As it is required in density formula.


Hope now you understand my problem..Thank you in advance

[Kirill-MIPT]

Hello! Study user defined real gas model in the udf guide. Only in such a way you can hook your own density law

[pakk]

Originally Posted by Priyank Mehta

Thank you for your response...And sorry for the inconvenience...
1. While interpret...It is showing structure reference not implemented...
2. While compile..It is showing the system can not find the path specified...

This are the problem related to the UDF error..

Other then this I am facing problem while writing a code.
1. I don't understand how to extract value for the mass fraction..As it is required in density formula.


Hope now you understand my problem..Thank you in advance

No, you don't understand what I wrote. If you want help, you have to really show what happens. Not describe it, but copy and paste. I am 95% sure that the answer to your question is easy once I can see what is written on your screen, but I can not see your screen. So show it. Copy the text.

[Priyank Mehta]

Hello....This is error I am getting while compiling


The system can not find the file specified.


The UDF library you are trying to load (D:\fluent _thesis \ dp0\ FFF\Fluent\libudf) is not compiled for 2ddp on the current platform (win64).

Thank you in advance

[Priyank Mehta]

The system can not find the file specified.

The UDF library you are trying to load (D:\fluent _thesis \ dp0\ FFF\Fluent\libudf) is not compiled for 2ddp on the current platform (win64).

[Micael]

At first glance, there is at least a problem with "mixture_species_loop"

It needs brackets

mixture_species_loop(m,sp,i)
{
   /* some instruction goes here */
}

[pakk]

Originally Posted by Priyank Mehta

Hello....This is error I am getting while compiling


The system can not find the file specified.


The UDF library you are trying to load (D:\fluent _thesis \ dp0\ FFF\Fluent\libudf) is not compiled for 2ddp on the current platform (win64).

Thank you in advance

This is not the error that you get when you are compiling. This is the error that you get when you are loading. The error that you get when you are compiling is above this.

[Priyank Mehta]

Hello thank you for suggestion
please help me to solve this error

Received a fatal Signal (segmental fault)
Error object: #f



#include "udf.h"

DEFINE_PROPERTY(dust,c,t)
{
int i;
float dT,dP,r,al,o2,al2,n2;
float Mw_i(int i);
Material *sp;
float rho_g=1.225;
float rho_s=2700;
float alp=0.0001859;
float sum=0.0;
dT=C_T(c, t);
dP=C_P(c, t);

mixture_species_loop(THREAD_MATERIAL(t),sp,i)
{
al=C_YI(c,t,1)/26.9815;
o2=C_YI(c,t,2)/31.9988;
al2=C_YI(c,t,3)/101.96;
n2=C_YI(c,t,4)/28.0134;

sum=al+o2+al2+n2;
}
r = (1+alp*((rho_s/rho_g)-1))*(dP/(sum*dT*8314.34));

return r;
}

hoping for reply thank you

[pakk]

Originally Posted by Priyank Mehta

Hello thank you for suggestion
please help me to solve this error

Received a fatal Signal (segmental fault)
Error object: #f

That is the error you get when you try to run. Also can not be used to help you...

Please read carefully: you have to give the error that comes up after you compile.
You click 'build', and something comes on your screen. What? Show me!

[Micael]

How many species do you have defined? If you have 4, then C_YI(c,t,4) is not going to work as index starts at zero (fourth species would be index 3).

[Priyank Mehta]

Thank you, Micael...this is very helpful and now it is working.

Thank you very much "pakk" and "Micael" for the help


One more question I have while using

dP=C_P(c, t); which pressure it will give static pressure of that cell or total
pressure (operating pressure + over pressure)

[pakk]

Static pressure.

To get absolute pressure, do

dP=C_P(c, t)+RP_Get_Float("operating-pressure");

[Priyank Mehta]

Thank you pakk

So what is the difference between
dP=C_P(c, t)+ p_operating;

dP=C_P(c, t)+RP_Get_Float("operating-pressure");

where o_operating I will define it as 101325 Pa



Thank you

[pakk]

The difference is that RP_Get_Float("operating-pressure") takes the value that you put into the Fluent simulation. If you change it in the Fluent set-up, it will also be changed in the UDF. So fewer chances of making a mistake.