[bloodflow]

I am trying to find the distance between a particle and the wall using a Compiled UDF and DPM_OUTPUT. To do this I want to use the C_WALL_DISTANCE(c,t) macro, but I am struggling to use it in parallel mode. I figure I should take the cell a particle is in using P_CELL(p), and then calculate the wall distance from there. The UDF compiles and loads without errors, but then you "start" the trajectory sampling you get SIGSEGV errors and figure it must require some extra constraints. My UDF is below if anyone has experience with the C_WALL_DISTANCE(c,t) macro please help.

DEFINE_DPM_OUTPUT(particledata,header,fp,p,t,plane )
{
cell_t c=P_CELL(p);
if(header)
{
par_fprintf_head(fp,"Particle-ID X-Position Y-Position Z-Position X-Velocity Y-Velocity Z-Velocity Time Wall_Dist\n ");
}
if(NULLP(p))
return;
par_fprintf(fp,"%d %" int64_fmt " %d %e %e %e %e %e %e %e %e \n",
P_INJ_ID(P_INJECTION(p)),
p->part_id,
p->part_id,P_POS(p)[0],P_POS(p)[1],P_POS(p)[2],P_VEL(p)[0],P_VEL(p)[1],P_VEL(p)[2],P_TIME(p),C_WALL_DIST(c,t));
}

[AlexanderZ]

if you are going to use C_WALL_DISTANCE(c,t) where is it?

for your code try this:

DEFINE_DPM_OUTPUT(particledata,header,fp,p,t,plane )
{
#if !RP_NODE
cell_t c=P_CELL(p);
if(header)
{
par_fprintf_head(fp,"Particle-ID X-Position Y-Position Z-Position X-Velocity Y-Velocity Z-Velocity Time Wall_Dist\n ");
}
if(NULLP(p))
return;
par_fprintf(fp,"%d %" int64_fmt " %d %e %e %e %e %e %e %e %e \n",
P_INJ_ID(P_INJECTION(p)),
p->part_id,
p->part_id,P_POS(p)[0],P_POS(p)[1],P_POS(p)[2],P_VEL(p)[0],P_VEL(p)[1],P_VEL(p)[2],P_TIME(p),C_WALL_DIST(c,t));
#endif
}

read Chapter 7: Parallel Considerations
in Ansys Fluent Customization Manual

[bloodflow]

Originally Posted by AlexanderZ

if you are going to use C_WALL_DISTANCE(c,t) where is it?

for your code try this:

DEFINE_DPM_OUTPUT(particledata,header,fp,p,t,plane )
{
#if !RP_NODE
cell_t c=P_CELL(p);
if(header)
{
par_fprintf_head(fp,"Particle-ID X-Position Y-Position Z-Position X-Velocity Y-Velocity Z-Velocity Time Wall_Dist\n ");
}
if(NULLP(p))
return;
par_fprintf(fp,"%d %" int64_fmt " %d %e %e %e %e %e %e %e %e \n",
P_INJ_ID(P_INJECTION(p)),
p->part_id,
p->part_id,P_POS(p)[0],P_POS(p)[1],P_POS(p)[2],P_VEL(p)[0],P_VEL(p)[1],P_VEL(p)[2],P_TIME(p),C_WALL_DIST(c,t));
#endif
}

read Chapter 7: Parallel Considerations
in Ansys Fluent Customization Manual

I am looking through that chapter but cannot work out which part of my code should be done on which node. The Wall distance macro is the last thing to be called in the "P->" string.

Using the command you suggest causes the error before you start the calculation, when you "start" the sampling.

"================================================= =============================

Node 999999: Process 29151: Received signal SIGSEGV.

================================================== ============================
MPI Application rank 9 exited before MPI_Finalize() with status 2
The fluent process could not be started."

So I'm just not sure how to use this in paralell.

[AlexanderZ]

try

C_WALL_DIST(F_C0(f,t),THREAD_T0(t))

best regrards

[bloodflow]

Originally Posted by AlexanderZ

try

C_WALL_DIST(F_C0(f,t),THREAD_T0(t))

best regrards

Do I need to define any additional things? Like "f"?

[AlexanderZ]

my bad,
yes
try

 f = P_FILM_FACE(p);

best regards

[bloodflow]

Thank you for your help but the UDF is still not able to compile. The code below:

DEFINE_DPM_OUTPUT(sampleparticles,header,fp,p,t,plane)
{
real f;
real distance;
f=P_FILM_FACE(p);
cell_t c=P_CELL(p);
distance=(C_WALL_DIST(F_C0(f,t),THREAD_T0(t)));
if(header)
 {
 par_fprintf_head(fp,"Particle-ID X-Position Y-Position Z-Position X-Velocity Y-Velocity Z-Velocity Time Wall Dist \n ");
 }
if(NULLP(p))
 return;
 par_fprintf(fp,"%d %" int64_fmt " %d %e %e %e %e %e %e %e %e \n",
 P_INJ_ID(P_INJECTION(p)),
 p->part_id,
 p->part_id,P_POS(p)[0],P_POS(p)[1],P_POS(p)[2],P_VEL(p)[0],P_VEL(p)[1],P_VEL(p)[2],P_TIME(p),distance);
#if REMOVE_PARTICLES
 MARK_PARTICLE(p, P_FL_REMOVED);
#endif
}

Gives the following error below:

in file included from /rds/bear-apps/handbuilt/software/ansys_inc/v181/fluent/fluent18.1.0/src/udf/udf.h:24:0,
                 from dpm.c:3:
dpm.c: In function sampleparticles:
/rds/bear-apps/handbuilt/software/ansys_inc/v181/fluent/fluent18.1.0/src/storage/mem.h:1002:52: error: array subscript is not an integer
 #define F_STORAGE(f,t,sv,type)(T_STORAGE(t,sv,type)[f])
                                                    ^
/rds/bear-apps/handbuilt/software/ansys_inc/v181/fluent/fluent18.1.0/src/storage/mem.h:1105:54: note: in definition of macro C_STORAGE_R
 #define C_STORAGE_R(c,t,n)(T_STORAGE_R_NO_CHECK(t,n)[c])
                                                      ^
dpm.c:14:11: note: in expansion of macro C_WALL_DIST
 distance=(C_WALL_DIST(F_C0(f,t),THREAD_T0(t)));
           ^
/rds/bear-apps/handbuilt/software/ansys_inc/v181/fluent/fluent18.1.0/src/storage/mem.h:2151:18: note: in expansion of macro F_STORAGE
 #define F_C0(f,t)F_STORAGE(f,t,SV_C0,cell_t *)
                  ^
dpm.c:14:23: note: in expansion of macro F_C0
 distance=(C_WALL_DIST(F_C0(f,t),THREAD_T0(t)));
                       ^
dpm.c:13:8: warning: unused variable c [-Wunused-variable]
 cell_t c=P_CELL(p);
        ^
dpm.c:10:6: warning: variable f set but not used [-Wunused-but-set-variable]
 real f;

[AlexanderZ]

f is a face and should be defined as:

face_t f;

seems you dont know the basis,
try to find information related to your problem in Ansys Fluent Customization manual first

best regards