Learning Forum

[Ales23]

Dear all,

I am trying to parallelize my calculation. However, I am facing a problem with a cell macro:

I have following code:

begin_c_loop_int(c,t)

{

Message("%e ",C_VOLUME(c,t));

}

end_c_loop_int(c,t)

For this simple code the simulation crashes. If I want to display C_P(c,t), it works.

Important note: It is 2D simulation.

Thank you for your help

[Karthik R]

Hello Can you please try running a script from the Fluent customization manual to make sure this is not a systems-related issue? Also, what is the objective of your UDF?
Karthik

[Ales23]

thank you. in the end I found the error. I excess a wrong thread

[Karthik R]

Awesome! Good luck with your projects.

[alexandra17]

Hi! I kind of have the same issue here and I do not think it relates with the thread. Every time I introduce the macro C_VOLUME my code crashes. I need to determine the volume of each cell in order to calculate the partial pressure. I have a one phase mixing model with two species air and water vapors. I narrowed down my code to this C_Volume thing because it refuses to work. Every time I insert this I get the sigsegv error. Does anyone has any idea what I am missing here pretty please?
#include "udf.h"
#include "mem.h"
DEFINE_ON_DEMAND(mass)
{
Domain *d = Get_Domain(1);
Thread *t;
cell_t c;
real vol;
begin_c_loop(c,t)
{
vol = C_VOLUME(c,t);
Message("%e\n", vol);
}
end_c_loop(c,t)
}

[Ales23]

you are not assigning a thread. You have only declared add t=Lookup_Thread(ID,d);
ID is equal to the domain zone

[alexandra17]

Hi Ales23! Thank you for your response! I've done that already as I am interested in a certain zone in my domain. The error remains the same. :(

[alexandra17]

I have checked to make sure the ID number corresponds to the zone I want and it does. The code I created works fine as long as I do not introduce the C_VOLUME macro.

[Ales23]

but in your code t=Lookup_Thread() is missing as I can see

[alexandra17]

I attach my code with the Lookup_thread that I missed. The error remains the same. The ID number is fine. I have checked it already.
#include "udf.h"
#include "mem.h"
DEFINE_ON_DEMAND(mass)
{
Domain *d = Get_Domain(1);
Thread *t;
int ID = 5;
t = Lookup_Thread(d, ID);
cell_t c;
real vol;
begin_c_loop(c,t)
{
vol = C_VOLUME(c,t);
Message("%e\n", vol);
}
end_c_loop(c,t)
}

[Ales23]

are you using interior ID or cell zone condition?

[alexandra17]

I am using the ID from a Boundary Condition, I guess that means that is interior ID right?

[Ales23]

you have to use the one from Cell conditions

[alexandra17]

Oh I see! Thank you very much! It works fine now. However, this is not what I intended. Could you please tell me how to determine the cell volumes for a certain boundary area? I need to calculate the condensation rate on a window in a room.

[Rob]

Have a look for the adjacent cells, https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v221/en/flu_udf/flu_udf_ConnectivityMacros.html%23flu_udf_macros_f_c0_c1 is a good starting point.