Learning Forum

[KeFon]

Good morning, 

I am trying to export data to compute a local property.

I want to retrieve data on faces that are on two opposite sides of a same wall. 
Because of the mesh construction, I expected the number of faces on both threads to be the same which I could confirm using the GUI:

Zone sizes on domain 1:

...

1089 quadrilateral wall faces, zone 4.

1089 quadrilateral wall faces, zone 7.

1089 quadrilateral wall faces, zone 5.

1089 quadrilateral wall faces, zone 18.

...

 

84124 nodes.

 

I am interested in faces in zone 4 and 5. 

 

Using a UDF to write on two files the data from these two zones, I get a different number of data for each zone. 

 

Here is a portion of the UDF to show how I defined the domain and threads and how I computed the number of elements :

 

DEFINE_EXECUTE_AT_END(export)

{

...

#if !RP_HOST

Domain *mix_domain=Get_Domain(1);

Thread *wall_thread_NH3=Lookup_Thread(mix_domain,5); 

Thread *wall_thread_water=Lookup_Thread(mix_domain,4); 

...

#endif

#if RP_NODE

size_water = THREAD_N_ELEMENTS_INT(wall_thread_water);

size_NH3 = THREAD_N_ELEMENTS_INT(wall_thread_NH3);

...

#endif

...

}

 

Which gives a total of 1725 faces for zone 5 and 1623 faces for zone 4.  

 

Could someone explain where the differences are coming from? 

 

Thank you.

[Rob]

If you try the UDF in serial what do you get? 

[KeFon]

Thank you very much for your fast answer. We had an issue with the license server and I could not try it until today.

Using Fluent in serial mode, I get the same number of faces from the macro THREAD_N_ELEMENTS_INT and from the GUI for both sides (1089).

Seeing this result, I tried to include a loop on the faces to count them in parallel mode using if (PRINCIPAL_FACE_P(f,*corresponding thread*)) first. The sum of the counted cells gave 1089 for both sides.  

I could use a first loop to get the number of faces and then a second one to get the properties but I would rather avoid that solution if possible. 

Thank you.