Learning Forum

[douniaextra1]

I wrote a UDF of a source term and temperature in function of time, but I'm not sure if it's right or no, can you please tell me if there is something wrong with it;

#include "udf.h"

#include

 

DEFINE_SOURCE(Energy_source, c, ct)

{

real source;

real flow_time;

real t = CURRENT_TIME;

 {

if ((t>21600)&&(t<72000)) 

 

{

source =(965.0*sin(3.14*(((t/3600)-6.0)/14)))*(0.81/0.002);

}

else

{

 source=0;

}     

        }

return source;

}

DEFINE_PROFILE(temperature, thread, T)

{

face_t f;

real t = CURRENT_TIME;

        begin_f_loop(f, thread)

        {

 

F_PROFILE(f, thread, T)=298+6.0*cos(3.14*(((t/3600)-14.0)/12.0));

        }

end_f_loop(f, thread)

}        

 

[Amine Ben Hadj Ali]

I would rather work on that without UDFs easy to do with Expressions. Look ok. By the way we do not debug UDFs.

[douniaextra1]

Thank you for replying me,

I tried the expression option in source term but I have a probleme with units 

the numbers that I used in the equations have a unity. they are not just a constantes, wich means that the equations has a correct unity but fluent doesnot know that. he only see the time variable (t)

do you have any idea about that ? 

by the way I really appreciate any comment from you, they are so helpfull.

Best regards,

Dounia

[Amine Ben Hadj Ali]

Apart from time other quantities in you expression do not have any dimensions if input into Fluent. You need to make the expression in the sinus function dimensionsless: time can be only added to time and you divide by time. So (t-7)/(12).. the whole expressioneds to be multiplied by 1[W m^-3].

All hints above are in the documentation.

[douniaextra1]

Thank you I got it know. can you please send me the documentation link that talks about this option so I can learn more.

but in my equation I have a condition of time 

if ((t>21600)&&(t<72000)) 

 

{

source =(965.0*sin(3.14*(((t/3600)-6.0)/14)))*(0.81/0.002);

}

else

{

 source=0;

}     

 

there is a condition option in Fluent "IF" but I don't know how to use it to you have any idea about that?

Thank you for keeping answering me ...

Best regards,

Dounia

[Amine Ben Hadj Ali]

Check FLUENT User's Guide.

IF(CONDITION, IF TRUE, IF FALSE).

[douniaextra1]

 thank you I got it know

Best regards,

Dounia