[andrk]

Hi everyone,
I want to interpret a udf file to ansys fluent 15, but i encounter this error:
"line 29: ads: undeclared variable"

Here is my code (I have bolded the line 29):

#include "udf.h"

DEFINE_ADJUST(adsorption,domain)

{

Thread *t;

cell_t c;

real E,A,P;

thread_loop_c(t,domain)

{

begin_c_loop(c,t)

{

real tem=C_T(c,t);

P=C_P(c,t)+RP_Get_Real("operating-pressure");

E=3080+18.9*tem;

A=8.31429*tem*log(1.47E9/P);

C_UDSI(c,t,ads)=71.6*exp(-A*A/(E*E));

}

end_c_loop(c,t)

}

}

DEFINE_ADJUST(q_ads, domain)

{

Thread *t;

cell_t c;

real dt;

thread_loop_c(t,domain)

{

begin_c_loop(c,t)

{

dt = RP_Get_Real("physical-time-step");

C_UDSI(c,t,q_ads)=C_UDSI_M1(c,t,q_ads)+0.15*dt*(C_ UDSI_M1(c,t,ads)-C_UDSI_M1(c,t,q_ads));

}

end_c_loop(c,t)

}

}

DEFINE_ADJUST(d_ads, domain)

{

Thread*t; cell_t c;

thread_loop_c(t,domain)

{

begin_c_loop(c,t)

{

C_UDSI(c,t,d_ads)=-0.532224*0.15*

(C_UDSI(c,t,ads)-C_UDSI(c,t,q_ads));

}

end_c_loop(c,t)

}

}

DEFINE_SOURCE(m_src,c,t,dS,eqn)

{

dS[eqn]=0.0;

return C_UDSI_M1(c,t,d_ads);

}

DEFINE_ADJUST(H_ads,domain)

{

Thread*t;

cell_t c;

real p_operating, p_static;

thread_loop_c(t,domain)

{

begin_c_loop(c,t)

{

C_UDSI(c,t,H_ads)=3080*

sqrt(log(71.6/C_UDSI_M1(c,t,ads)));

}

end_c_loop(c,t)

}

}

DEFINE_SOURCE(esrc,c,t,dS,eqn)

{

real e_source;

e_source=-C_UDSI_M1(c,t,d_ads)*

0.496056352e3*3080

*sqrt(log(71.6/C_UDSI_M1(c,t,ads)));

dS[eqn] = 0.0;

return e_source;

}

Hope someone can help me to solve it.
Many thanks!

[AlexanderZ]

C_UDSI(c,t,ads)=71.6*exp(-A*A/(E*E));

what is "ads" here? why do you use ads?


Best regards

[andrk]

Originally Posted by AlexanderZ

C_UDSI(c,t,ads)=71.6*exp(-A*A/(E*E));

what is "ads" here? why do you use ads?


Best regards

I want "ads" represent the absolute adsorption isotermal

represent this equation:

na = 71.6 * exp [-(A)^2/E^2]

[pakk]

Very nice that you want that, but how can the compiler know that?
You never tell the compiler what "ads" is...

Personally, I would just replace it by the number 0.

[andrk]

Originally Posted by pakk

Very nice that you want that, but how can the compiler know that?
You never tell the compiler what "ads" is...

Personally, I would just replace it by the number 0.

I'm new at CFD software, my senior was using this code, so I don't know some, can you tell me how the compiler can read "ads"? Many thanks

[AlexanderZ]

As pakk has mentioned, I think you should change ads or q_ads/d_ads to 0 everywhere in your udf code where UDSI is.

was

C_UDSI(c,t,ads)

to be

C_UDSI(c,t,0)

[andrk]

Originally Posted by AlexanderZ

As pakk has mentioned, I think you should change ads or q_ads/d_ads to 0 everywhere in your udf code where UDSI is.

was

C_UDSI(c,t,ads)

to be

C_UDSI(c,t,0)

If I change that, then how to differentiate 4 same equations C_UDSI(c,t,0)? While I hsve to use in this equation

C_UDSI(c,t,d_ads)=-0.532224*0.15*(C_UDSI(c,t,ads)-C_UDSI(c,t,q_ads));

Will it work if just be the following equation?

C_UDSI(c,t,0)=-0.532224*0.15*(C_UDSI(c,t,0)-C_UDSI(c,t,0));

[AlexanderZ]

to differentiate variables you need to use integer values, for instance
ads change to 0
d_ads change to 1 and so on

You may find more details in Ansys Fluent Customization manual

best regards

[andrk]

Originally Posted by AlexanderZ

to differentiate variables you need to use integer values, for instance
ads change to 0
d_ads change to 1 and so on

You may find more details in Ansys Fluent Customization manual

best regards

Thank you so much, I'm really really newbie, it look likes very easy evidently, again, thank you so much

[arun km]

Originally Posted by andrk

Thank you so much, I'm really really newbie, it look likes very easy evidently, again, thank you so much

Did you resolve the issue