Learning Forum

[ritwik]

I am modelling an adsorption model for a zeolite column. The UDF for mass source term is:

#include "udf.h"

int ads;

int domain_q_ads = 0;

int domain_d_ads = 1;

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,0)=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,1)=-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);

}

When i try to compile, the console shows this error and the fluent window stopped working. I am allocating 2 memory location for UDM.

[DrAmine]

Look carefully into the lines where you want to access the previous time step results..

[DrAmine]

And ensure you are defining two UDS's.

[ritwik]

Yes i am defing two UDS

[ritwik]

I am not understanding. I am new to the fluent and udfs. Can you please elaborate?

Thank you

[DrAmine]

So then please go through the Customization Manual and if possible a couple of Self paced Training on the Ansys Learning Hub.
Another Hint: what is q_ads? Is it defined somewhere?

[ritwik]

#include "udf.h"
int i;
/*Adsorption*/
DEFINE_ADJUST(adsorption,d)
{
Thread*t; cell_t c; real E,A,P;
thread_loop_c(t,d)
{
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,i)=71.6*exp(-A*A/(E*E));
}
end_c_loop(c,t)
}
}
DEFINE_ADJUST(q_ads, d)
{
Thread *t;cell_t c; real dt;
thread_loop_c(t,d){ /*q_ads is the UDF name i am defining*/
begin_c_loop(c,t){
dt = RP_Get_Real("physical-time-step")/*int i is number of UDS*/
C_UDSI(c,t,i)=C_UDSI(c,t,i)+0.15.*dt*(C_UDSI(c,t,i)-C_UDSI(c,t,i));}
end_c_loop(c,t)
}
}
I am allocating 2 UDS and 4 UDM
After go through the manual, i modified the UDF. Can you please tell me, where i have gone wrong?

[DrAmine]

i is undefined for UDS. It should be 0, 1 2 etc. to refer to the proper UDS.

[ritwik]

#include "udf.h"
int i;
DEFINE_ADJUST(adsorption,d)
{
Thread*t; cell_t c; real E,A,P;
thread_loop_c(t,d)
{
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,0)=71.6*exp(-A*A/(E*E));
}
end_c_loop(c,t)
}
}
DEFINE_ADJUST(q_ads, d)
{
Thread *t;cell_t c; real dt;
thread_loop_c(t,d){
begin_c_loop(c,t){
dt = RP_Get_Real("physical-time-step")
C_UDSI(c,t,0)=C_UDSI_M1(c,t,i)
+0.15.*dt*(C_UDSI_M1(c,t,0)-C_UDSI_M1(c,t,1));}
end_c_loop(c,t)
}
}
I have changed it.
But same problem is coming.

[Rob]

You've not defined a few of the variables (REAL, INTEGER etc) and I wonder if using a comma is permitted in C, you might need a full stop for a decimal. As you're using 2021 compile the code with the built in compiler: if nothing else it'll give us a better idea if the code is OK.

[DrAmine]

Again your UDS and index. Check what Fluent reports when compiling.

[ritwik]

when i tried to compile the udf
The udf is:
#include "udf.h"
int ads;
real C1;
/*Adsorption*/

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,0)=71.6*exp(-A*A/(E*E));
C1 = C_UDSI(c,t,0);}
end_c_loop(c,t)}
}
/*Mass source term*/

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,0)=C_UDSI(c,t,0)
+0,15*dt*(C1-C_UDSI(c,t,0));}
end_c_loop(c,t);}
this error is showing.
Can you please help me? What is this error meant?

[Secorreaz]

In the end your udf was able to compile correctly.??

[ritwik]

This udf was not compiled, I have to modified in order to get compiled succesfully

[DrAmine]

.

[Secorreaz]

And did you manage to modify it to run successfully or did you abandon the work?

[ritwik]

No, It is running successfully

[mechE]

Ritwik, can you please share how did you resolve the problem?

[Amani Chouat]

i work in the some problem , (adsoptive hydrogen storage using Udf) , how did you resolve the problem please ,

Ps:i don't have much idea about UDF