Learning Forum

[Burhan Ibrar]

Hello Dear,

I hope this thread will find you well.

I am doing a very simple test where i use 6dof udf but in that udf i want to get the velocity from the actual results. The main problem is complex but i receive the same error as shown below. I just want to have some results in my udf through looping or some other way which i do not know. I also wrote the UDF here below for reference. The thing is that when i do not use a loop then it works fine but i need to have a loop to get the velocity or some other variable from the results.

I hope you understand the problem and give me feedback asap with your experience. Thank you.

UDF:

/************************************************** *****

SDOF property compiled UDF with external forces/moments

************************************************** *****/

#include "udf.h"

static real acc = 4.631;

static real mass = 5;

static real velocity;

DEFINE_SDOF_PROPERTIES(acce, prop, dt, time, dtime)

{

prop[SDOF_MASS] =5;

prop[SDOF_IXX] = 5.2e-5;

prop[SDOF_IYY] = 4.1667e-3;

prop[SDOF_IZZ] = 1;

prop[SDOF_ZERO_TRANS_X] = False;/* boolean, allow translation in x-direction */

prop[SDOF_ZERO_TRANS_Y] = True; /* boolean, suppress translation in y-direction */

prop[SDOF_ZERO_TRANS_Z] = True; /* boolean, suppress translation in z-direction */

prop[SDOF_ZERO_ROT_X] = True; /* boolean, suppress rotation around x-axis */

prop[SDOF_ZERO_ROT_Y] = True; /* boolean, suppress rotation around y-axis */

prop[SDOF_ZERO_ROT_Z] = True; /* boolean, allow rotation around z-axis */

{

if(time >= 0) {

Thread *f_thread;

face_t f;

velocity=0;

begin_f_loop(f, f_thread)

{

velocity += F_U(f, f_thread);

}

end_f_loop(f, f_thread)

Message(" V1 %d /n",velocity);

prop[SDOF_LOAD_F_X] = mass*acc;

}

}

}

Error:

"V1 0 /n

=========================

==============

================================================== ================================================== ============

Node 5: Process 20896: Receiv============================================ ==============

========================================

Node 1: Proc=================ess 20948: Received signal ====================SIGSEGV.

================================================== ============================================

=========================================

=============================Node 3: Process 20648: Received si=ed signal gn======================SIGSEGV.

================================================== =al SI========G===============================

S==EG====V.

=======

No======

============

Node 0: Prde 2: Process 17612: Received sig=====================o========================= ========================================

============ncess 1936: Received signal Sal SIGSEGV.

=========================IGSEGV.

================================================== ================================================== ========

Node 4: ===========Process 10852: Rece======ived signal SIGSEGV.===

================================================== =======================

==================

999999: mpt_accept: error: accept failed: No such file or directory"

[Surya Deb]

Hello,
You f_thread seems undefined. You need to fetch the f_thread. You can use Lookup_Thread macro. check here [https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v211/en/flu_udf/flu_udf_sec_special_macros.html?q=lookup%20thread].
Also check your logic regarding the summation of the velocity.
Regards SD

[Burhan Ibrar]

Hello sdeb thank you so much for your reply and it helped me a lot. But i have a problem where i am using overset model and now what i did that i define the motion on walls and for overset fluid domain i defined relative motion and UDF with only properties e.e mass, rotation and translation. Is this the right way to do it because when i define the same udf with motion on both then i get errors.
2nd thing is that i have attached the code below when i used my calculation for (#if !RP_HOST) and solving it parallel but in results i have variable output 6 times and every variable has a different value. If you can help me to get the one value which should be equal to the one we can see in dynamic mesh window. What i understood from manual that all variable values which i see in console are from different nodes and now i want to let them communicate so get the right value which i do not know yet.
And for writing a file with variables like time and velocity should i also use #if !RP_HOST or #if RP_NODE, etc.?
your help will really appreciated. thank you.

/*******************************************************
SDOF property compiled UDF with external forces/moments
*******************************************************/
#include "udf.h"

static real acc = 4.631;
static real mass = 5;
static real velocity, vel, area_tot, area[3];
DEFINE_SDOF_PROPERTIES(acce, prop, dt, time, dtime)
{


prop[SDOF_MASS] =5;
prop[SDOF_IXX] = 8.333e-4;
prop[SDOF_IYY] = 4.1667e-3;
prop[SDOF_IZZ] = 5.2e-5;
prop[SDOF_ZERO_TRANS_X] = False;/* boolean, allow translation in x-direction */
prop[SDOF_ZERO_TRANS_Y] = True; /* boolean, suppress translation in y-direction */
prop[SDOF_ZERO_TRANS_Z] = True; /* boolean, suppress translation in z-direction */
prop[SDOF_ZERO_ROT_X] = True; /* boolean, suppress rotation around x-axis */
prop[SDOF_ZERO_ROT_Y] = True; /* boolean, suppress rotation around y-axis */
prop[SDOF_ZERO_ROT_Z] = False; /* boolean, allow rotation around z-axis */
{
#if !RP_HOST
Thread *t;
face_t f;
Domain *domain;
int nid;
domain = THREAD_DOMAIN (DT_THREAD (dt));
nid = THREAD_ID (DT_THREAD (dt));
t = Lookup_Thread (domain, nid);

velocity=0.0;
area_tot=0;
#endif

#if !RP_HOST
begin_f_loop(f, t)
if (PRINCIPAL_FACE_P(f, t))
{
F_AREA(area,f,t);
area_tot += NV_MAG(area);
velocity += F_U(f, t)*NV_MAG(area);
}
end_f_loop(f, t)



/*area_tot=PRF_GRSUM1(noface);
velocity=PRF_GRSUM1(velocity);*/
#if RP_NODE
vel = velocity/area_tot;

Message("\nV1 %f Area Total %f /n",vel, area_tot);
#endif

#endif

[Burhan Ibrar]

hello sdeb Please read above. I forgot to quote your message.

[Burhan Ibrar]

The results are as follows. Initially the variable V1 has 6 different values but after some time only one has a value and other has ind value which i do not understand. And in later stages the value is equal to the one in dynamic mesh. I need to have only one accurate value which you can see in 2nd results which i can use further in my program for comparison. First results
V1 0.004384 Area Total 0.001615 /n done.
Updating mesh at time level N...
V1 0.004380 Area Total 0.009207 /n
V1 0.004389 Area Total 0.004913 /n
V1 0.004389 Area Total 0.005528 /n
V1 0.004385 Area Total 0.001727 /n
V1 0.004380 Area Total 0.000947 /ndone.

2nd Results
V1 -nan(ind) Area Total 0.000000 /n done.
Updating mesh at time level N...
V1 -nan(ind) Area Total 0.000000 /n
V1 0.030577 Area Total 0.023936 /n
V1 -nan(ind) Area Total 0.000000 /n
V1 -nan(ind) Area Total 0.000000 /n
V1 -nan(ind) Area Total 0.000000 /ndone.

[Surya Deb]

Hello,
It is not possible to check your entire UDF. But I think you might be missing commands to transfer from node to host after global summing.
Check this link for a parallel UDF example. [https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v212/en/flu_udf/flu_udf_sec_parallel_example.html?q=parallel]

Regards SD

[Burhan Ibrar]

Thank you Sdeb,
Issue is resolved.