[alinik]

Hi all,

I need to calculate the distance from wall in my UDF. Apparently C_WALL_DIST(c,t) is no longer available and I cannot use it in my UDF.
Does anybody know any other solution? Or if fluent has replaced it with some other kind of Macro?

Thanks,
Ali

[ghorrocks]

Moving post to the fluent forum. Please ensure you post on the right forum in future.

[fanch33]

Hi,

which version of Fluent are you using ?
I am using C_WALL_DIST for v14.5 and v16, it works.
Write your UDF here if you want.

Fanch

[alinik]

Hi,

I am using Fluent v 16.2 and it does not work there.

[fanch33]

Maybe you can try like this :
C_UDMI(c,t,0) = C_STORAGE_R(c,t,SV_WALL_DIST)

It is strange as in the headers file of v16.2, in the mem.h file, C_WALL_DIST is defined : #define C_WALL_DIST(c,t) C_STORAGE_R(c,t,SV_WALL_DIST)

Fanch

[fanch33]

Do you use #include "mem.h" at the beginning of your UDF code ?

Fanch

[alinik]

Fanch,

Yes, I have included "mem.h" file.
I tried what you recommended but I received a segmentation error.
C_UDMI(c,t,0) = C_STORAGE_R(c,t,SV_WALL_DIST)

I have defined a UDM, so that would not be the problem.

Are you sure that C_WALL_DIST is defined in mem.h? How can I see the content of that? is there anyway that I can see the content of that header file?

Thanks,
Ali

[fanch33]

If Fluent is installed on your local computer, you can go to this directory :
C:\Program Files\ANSYS Inc\v162\fluent\fluent16.2.0\src et you have all the headers file, with the definitions of all functions.

I only use C_WALL_DIST in DEFINE_ON_DEMAND macro. I don't understand why it is not working for you :/

I can show you my code if you want, maybe it comes from the loop you are using or something else

Fanch

[alinik]

Unfortunately I cannot access those files since I run fluent from a remote machine and I do not have admin privileges.
That would be great if you can do it. I can compare it with my own code and I will post my code in the next post for you to see.

thanks,
Ali

[fanch33]

#include "udf.h"
#include "mem.h"
#include "math.h"
#include "dll.h" /* do not think it is useful in this case */
DEFINE_ON_DEMAND(y_plus)
{
#if RP_NODE
Domain *d;
Thread *t;
cell_t c;
face_t f;
d= Get_Domain(1);
if (! Data_Valid_P())
return;

thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
C_UDMI(c,t,1) = C_WALL_DIST(c,t);
}
end_c_loop(c,t)
}
#endif
}

[alinik]

Fanch,

I receive segmentation error whenever I use C_WALL_DIST.
I even replicated the same code that you have posted here in another UDF and received the same error. I double-checked everything like UDMs and UDSs and everything seems to be fine.
It successfully is compiled but if I hook it to fluent, I will receive the error.
I will post my UDF here in the next post for you to see.

[alinik]

In this function I have to use wall distance macro to find F2 and this is where the segmentation error is produced.

real F2(cell_t c, Thread *t){

real c1,c2,d1;

c1=2*sqrt(C_UDSI(c,t,k))/(betastar*C_UDSI(c,t,w)*C_WALL_DIST(c,t));
c2=500*C_MU_L(c,t)/C_R(c,t)/(pow(C_WALL_DIST(c,t),2)*C_UDSI(c,t,w));

d1= MAX(c1,c2);
return tanh(d1*d1);
}

If I replace the C_WALL_DIST(c,t) with some constant value the error will go away.

[alinik]

Fanch,

did you try my code?

[alinik]

I asked a UDF specialist and he said this macro (C_WALL_DIST) is still available and it just has to be filled first.
Unfortunately I cannot ask him anymore.
Does anybody know what does that mean?