[truffaldino]

I would be grateful if someone could help me to fix the problem.

I am using THREAD_ID(t) in if statement to set different visosities in different zones. But it does not work in " if (Thread_ID(t)==...) " statement in my UDF. Whe I run fluent with this UDF, it does not distingush between zones.

It is a very simple code, what could be wrong here?:

PHP Code:


#include "udf.h"

#define xtop -1.
#define xbot 0.

#define rho 1.225
#define nu 1.4607E-5

#define C3 357.9

#define idtop 11
#define idbot 10

DEFINE_TURBULENT_VISCOSITY(mu_t, c, t)
{

real mu;
real nut;
real xi;
real r[ND_ND];

C_CENTROID(r,c,t);

    if(THREAD_ID(t)==idtop)
    {

            if(r[0]>xtop)
            {

            nut=C_NUT(c,t);
            xi=nut/nu;
            xi=xi*xi*xi;
            mu=rho*nut*xi/(xi+C3);

            }
            else 
            {

            mu=0;

            };

    };

    if(THREAD_ID(t)==idbot)
    {

            if(r[0]>xbot)
            {
        
            nut=C_NUT(c,t);
            xi=nut/nu;
            xi=xi*xi*xi;
            mu=rho*nut*xi/(xi+C3);

            }

            else
            {

            mu=0;

            };

    };

return mu;

} 


[Amir]

Hi,
for simple debugging, would you use a Message command to check whether it enters a if statement or not?

[truffaldino]

Originally Posted by Amir

Hi,
for simple debugging, would you use a Message command to check whether it enters a if statement or not?

I have checked it without message: I have just removed "if(THREAD_ID...) statements and everything works fine, as seen from postprocessing, except it chooses one viscousity function for all zones, so it does not enter "if(THREAD_ID...) statements

[truffaldino]

I have checked it without message: I have just removed "if(THREAD_ID...) statements and everything works fine, as seen from postprocessing, except it chooses one viscousity function for all zones, so it does not enter "if(THREAD_ID...) statements

[truffaldino]

And there is another strange thing: when I put "Message" or "Error" statement, interpretor says:

function "CX_Message" not founs (pc=80)

or

function "CX_Primitive_Error" not found (pc=80)

[Amir]

Originally Posted by truffaldino

I have checked it without message: I have just removed "if(THREAD_ID...) statements and everything works fine, as seen from postprocessing, except it chooses one viscousity function for all zones, so it does not enter "if(THREAD_ID...) statements

just a suggestion:
do not introduce idtop & idbot as:

#define idtop 11
#define idbot 10

try in define macro:

int idtop=11
int idbot=10

it may help !

[truffaldino]

Originally Posted by Amir

just a suggestion:
do not introduce idtop & idbot as:

#define idtop 11
#define idbot 10

try in define macro:

int idtop=11
int idbot=10

it may help !

Thanks Amir,

I have already tried this: it does not help. I am wanderin, could it be an interpretor problem, since it does not recognize commands like "Message" and "Error"

[Amir]

Originally Posted by truffaldino

Thanks Amir,

I have already tried this: it does not help. I am wanderin, could it be an interpretor problem, since it does not recognize commands like "Message" and "Error"

you're right if you have such these problems with other UDFs with the same headers. is it the case?

[truffaldino]

Thanks Amir,

I have tried with other udf Message and Error macros do not work, so there is something wrong with an interpretter indeed.

[truffaldino]

I have solved the problem: it turns out that zone ID numbers must be taken as assigned by gambit (as in mesh file) and not as shown by fluent!

As for "Error" and "Message" makros they do not work, but can be replaced by "printf".

[Amir]

really? I've used ID's that FLUENT shows for my UDFs before and they've worked.
would you please also checked that with other versions of FLUENT?

[natantyt]

Hi

I've got the same problem with my UDF to define different diffusivities for different zones , did you solve this? I appreciate your suggestions. Did you define the zone ID from boundary box or cell zone box?

Originally Posted by truffaldino

I would be grateful if someone could help me to fix the problem.

I am using THREAD_ID(t) in if statement to set different visosities in different zones. But it does not work in " if (Thread_ID(t)==...) " statement in my UDF. Whe I run fluent with this UDF, it does not distingush between zones.

It is a very simple code, what could be wrong here?:

PHP Code:

 
#include "udf.h"
 
#define xtop -1.
#define xbot 0.
 
#define rho 1.225
#define nu 1.4607E-5
 
#define C3 357.9
 
#define idtop 11
#define idbot 10
 
DEFINE_TURBULENT_VISCOSITY(mu_t, c, t)
{
 
real mu;
real nut;
real xi;
real r[ND_ND];
 
C_CENTROID(r,c,t);
 
    if(THREAD_ID(t)==idtop)
    {
 
            if(r[0]>xtop)
            {
 
            nut=C_NUT(c,t);
            xi=nut/nu;
            xi=xi*xi*xi;
            mu=rho*nut*xi/(xi+C3);
 
            }
            else 
            {
 
            mu=0;
 
            };
 
    };
 
    if(THREAD_ID(t)==idbot)
    {
 
            if(r[0]>xbot)
            {
 
            nut=C_NUT(c,t);
            xi=nut/nu;
            xi=xi*xi*xi;
            mu=rho*nut*xi/(xi+C3);
 
            }
 
            else
            {
 
            mu=0;
 
            };
 
    };
 
return mu;
 
} 


[truffaldino]

Hello Nathan,

Yes I have solved the problem but it was a long time ago: I remember that it turns out that zone ID numbers must be taken as assigned by gambit (as in mesh file) and not as shown by fluent! That is why my procedure was not working. So, in file I have presented above, it was necessary to change values of idtop and idbottom to those given by gambit in mesh file.

Truffaldino

[truffaldino]

Originally Posted by Amir

really? I've used ID's that FLUENT shows for my UDFs before and they've worked.
would you please also checked that with other versions of FLUENT?

Hello Amir,

I was not aware of your messge, sorry for late responce. Unfortunately I have no access to different versions of Fluent, so I cannot check it.

Truffaldino

[Kanarya]

Hi, I have problem to save mass flow rate at outlet
I did following udf but it seems UDMI doesnt work because it is always zero.
is there anyone who can help me?

thanks in advance!
here is my code:
#include "udf.h"
DEFINE_EXECUTE_AT_END(measure_mass_flow)
{
real mass_flow;
Domain *d=Get_Domain(1);
cell_t c;
face_t f;
Thread *mixture_thread = Lookup_Thread(d,4);
Thread **pt = THREAD_SUB_THREADS(mixture_thread);
Thread *tp = pt[0];
Thread *ts = pt[1];

mass_flow=0.;

mp_thread_loop_f(mixture_thread,d,pt)

if( THREAD_ID(mixture_thread) == 4 )

{
begin_f_loop(f,mixture_thread)

{


F_UDMI(f,mixture_thread,0)+= F_FLUX(f,tp);


}
end_f_loop(f,mixture_thread)
}



}

[zwbmimi]

Hi, I also have this problem and fix it by using the ID provided by FLUENT, which can be found in BC panel.

[Kanarya]

hi Zwbmimi,
thanks for the answer!

I did it as well. But now i have problem to use it in parallel.
Can you use it in parallel..?

best regards

Originally Posted by zwbmimi

Hi, I also have this problem and fix it by using the ID provided by FLUENT, which can be found in BC panel.

[zwbmimi]

Yes, my UDF works in parallel.

Originally Posted by Kanarya

hi Zwbmimi,
thanks for the answer!

I did it as well. But now i have problem to use it in parallel.
Can you use it in parallel..?

best regards

[Kanarya]

for what kind of application are you using it?
can you help me to make it parallel?

thanks in advance...

Originally Posted by zwbmimi

Yes, my UDF works in parallel.

[zwbmimi]

Hi, i include the thread id in source terms of my uds. Does your code work well in parallel without the tread id? I'm happy to help.

Originally Posted by Kanarya

for what kind of application are you using it?
can you help me to make it parallel?

thanks in advance...