CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT > Fluent UDF and Scheme Programming

Problems with UDF in parallel mode

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   October 2, 2015, 09:48
Question Problems with UDF in parallel mode
  #1
New Member
 
Rikard
Join Date: Sep 2015
Posts: 4
Rep Power: 11
rikfr986 is on a distinguished road
Hi!
I have written a UDF to calculate the average value of a passive scalar at the outlet boundary to use it as a prescribed value at the inlet. The code works fine when in serial mode but not in parallel. seems like only one of the cores got the right value!? or how to express it.

Would be very pleased if someone knows what's wrong or could guide me in right direction!

see code below

#include "udf.h"
#include "mem.h"

real concavg, concavg1;
real conc;

DEFINE_EXECUTE_AT_END(out_ave)
{

Domain *d;
real area,
real area_tot;

real A[ND_ND];
Thread *t;
face_t f;

d=Get_Domain(1);
t=Lookup_Thread(d,5);

area=0;
area_tot=0;
conc=0;
concavg=0;
concavg1=0;


begin_f_loop(f,t)
{

F_AREA(A,f,t);
area=NV_MAG(A);
area_tot+=area;

conc=F_UDSI(f, t, 0);
concavg += conc*area;

concavg1=concavg/area_tot;

printf("\n area_tot = %f\n",area_tot); /*print once for every cell face on outlet, counts to the right area, OK!*/
printf("\n concavg = %f\n",concavg1); /*print once for every cell face on outlet, right value, OK!*/


}
end_f_loop(f,t)

printf("\n area_tot2 = %f\n",area_tot);/* Print once for every core, first one OK the other three =0??!*/
printf("\n concavg2 = %f\n",concavg1);


}

DEFINE_PROFILE ( inl_uds, t, i)
{

face_t face;
face_t f;
real flow_time, inlvalue;

flow_time=RP_Get_Real("flow-time");

if(flow_time<0.5)
{
begin_f_loop(face, t)
{
F_PROFILE(face, t, i)=1;
}
end_f_loop(face, t)
}
else
{
begin_f_loop(face, t)
{
inlvalue=concavg1;/*F_UDMI(f,t,0);*/

F_PROFILE(face, t, i)=inlvalue;

}
end_f_loop(face, t)
}
}
rikfr986 is offline   Reply With Quote

Old   October 6, 2015, 12:17
Default
  #2
Senior Member
 
Bruno
Join Date: Mar 2009
Location: Brazil
Posts: 277
Rep Power: 21
brunoc is on a distinguished road
The documentation has a section about parallelizing UDFs. You can't just use the version you use in serial, since part of the information can't be accessed by all compute nodes.

For instance, the averaging procedure you're doing won't work since some of the compute nodes might not have any cells on the zone you're looking for. That is why you're getting a null area on some partitions.

Search for Global Reduction Macros in the doc and make the appropriate corrections (but read the entire parallel section to know other things you'll need to change).

Cheers.
brunoc is offline   Reply With Quote

Reply

Tags
parallel, scalar, udf


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
problem with compiling boundary condition udf in parallel mode chem engineer Fluent UDF and Scheme Programming 11 June 29, 2015 07:23
decomposePar is missing a library whk1992 OpenFOAM Pre-Processing 8 March 7, 2015 08:53
compiling UDF for moving mesh in parallel mode vespa50l Fluent UDF and Scheme Programming 3 September 22, 2014 12:11
UDF parallel error: chip-exec: function not found????? shankara.2 Fluent UDF and Scheme Programming 1 January 16, 2012 23:14
problem using property udfs in parallel mode EllenW Fluent UDF and Scheme Programming 5 July 10, 2009 05:31


All times are GMT -4. The time now is 19:51.