Obtain equation residuals in UDF
 

Hello!

I'm writing an UDF that makes an optimization.
So every iteration, it must check if there was convergence in the solver, so I can make the proper changes in my profiles.

Is there a way to return the current solver residuals?

Regards,
Robert

Well not in udf but here is a scheme line that gives you the residuals for the specified or current iteration (see also Wiki Fluent Scheme):

This is an example to print the residuals on the console.
#include "udf.h"
DEFINE_ON_DEMAND(residual_list)
{
int nw;
real scaled_res;
Domain*domain=Get_Domain(1);
for(nw=0; nw<MAX_EQNS; ++nw)
{
if(strlen(DOMAIN_EQN_LABEL(domain,nw))>0)
{
if(0==DOMAIN_RES_SCALE(domain,nw)[nres-1])
DOMAIN_RES_SCALE(domain,nw)[nres-1]=1;
scaled_res=DOMAIN_RES(domain,nw)[nres-1]/DOMAIN_RES_SCALE(domain,nw)[nres-1];
Message("%s equation,residual=%g\n",DOMAIN_EQN_LABEL(domain,nw ),scaled_res);
}
}
}

What is nres?
 

Hi Ji,
Nice to see some undocumented macros at use, but what is 'nres' variable representing?

nres is the current number of residuals.

:( Dear my friends.Now, a similar problem I had come acrossed when edit a udf, while i copy this code and then try to compile as executable progame, an issue come out, the fluent tell me that subscript required array or poiter types. I think it maybe caused by the nres. Who can tell me how to treat it. I only want to obtain the residuals on the current time in my udf.
If anybody could have the same question and have solve it,please help me. Thank you.

...post the error
 

Could you post the error you get not from your own memory, but from the computer screen?

Ok:)
(system "copy "C:\PROGRA~1\ANSYSI~1\v130\fluent"\fluent13.0.0\sr c\makefile_nt.udf "libudf\win64\2ddp\makefile" ")
已复制 1 个文件。
(chdir "libudf")()
(chdir "win64\2ddp")()
# Generating ud_io1.h
test2.c
..\..\src\test2.c(11) : error C2109: 下标要求数组或指针类型
..\..\src\test2.c(12) : error C2109: 下标要求数组或指针类型
..\..\src\test2.c(13) : error C2109: 下标要求数组或指针类型
..\..\src\test2.c(13) : error C2109: 下标要求数组或指针类型
Done.
"下标要求数组或指针类型/chinese" means "subscript requried arrays or pointer types":confused:
Thank you!!

Is it possible to post the code? Apparently you're trying to use as array something that's not.

:)
I am very appreciated for your help. In order to avoid to determine the convergence in my udf according to the residuals, I had choosen another
variable at the exit boundary ,and by monitoring its change to do the next work.