[sooraj546]

Kindly read the attachment before going through the code.
sample explanation:
Add a source term to the cells adjacent to a wall
Problem/Description: How do I add a source term to the cells adjacent to a wall?
Solution:
A source term can be added with a UDF (using the macro ‘DEFINE_SOURCE’).
The UDF below enables: - To add a source term equals to 10 to the cells adjacent to the boundary with the ID equal to ‘boundaryID’ (defined below); - To add a source term equals to 5 to the other cells.
The source term is stored in User-Defined Memory (UDM) via the macro DEFINE_ON_DEMAND. The macro DEFINE_SOURCE returns the value of the UDM.
If the source term changes during the calculation, the DEFINE_ON_DEMAND macro can be adapted in a DEFINE_ADJUST macro.
Here is the code:
#include "udf.h"
/*
This UDF enables
- to add a source term equals to 10 to the cells adjacent to the boundary with the ID equals boundaryID (defined below);
- to add a source term equals to 5 to the other cells.
The source term is stored in User-Defined Memory (UDM) via the macro DEFINE_ON_DEMAND.
The macro DEFINE_SOURCE returns the value of the UDM.
If the source term changes during the calculation, the DEFINE_ON_DEMAND macro can be adapted in a DEFINE_ADJUST macro.
*/
int boundaryID=1;
DEFINE_SOURCE(source,c,t,dS,eqn)
{
return C_UDMI(c,t,0);
}
DEFINE_ON_DEMAND(on_demand_calc)
{
face_t f;
cell_t c;
Domain *domain=Get_Domain(1);
Thread *t;
thread_loop_c(t,domain)
{
begin_c_loop(c,t)
{
C_UDMI(c,t,0)=5;
}
end_c_loop(c,t)
}
thread_loop_f(t,domain)
{
if (THREAD_ID(t)==boundaryID)
{
begin_f_loop(f,t)
{
C_UDMI(F_C0(f,t),THREAD_T0(t),0)=10;
}
end_f_loop(f,t)
}
}
Message0("\n\n UDF DONE \n\n");
}


My code:

DEFINE_ADJUST(calc,domain)
{

face_t f;
Thread *t;
real mf_co,mf_co2;/* variable declaration */
real c_co,c_co2;/* variable declaration */

int boundaryID=1; /*wall ID*/
thread_loop_f(t,domain)
{
if (THREAD_ID(t)==boundaryID)
{
begin_f_loop(f,t)
{

mf_co=C_YI(f, t, 3);
mf_co2=C_YI(f, t, 4);

conc_co=mf_co*C_R(f, t);

C_UDMI(F_C0(f,t),THREAD_T0(t),0)=-0.0092976*c_co;
}
end_f_loop(f,t)
}
Message0("\n\n UDF DONE \n\n");
}
}

DEFINE_SOURCE(CO_source,c,t,dS,eqn)
{
real x[ND_ND];
real source;
source = C_UDMI(F_C0(c,t),THREAD_T0(t),0);
dS[eqn] = 0.0;

return source;
}

segmentation fault is coming because of this line i guess : C_UDMI(F_C0(f,t),THREAD_T0(t),0)=-0.0092976*c_co;

Thanks a lot in advance . Kndly help me out to get rid of this ......................................

[AlexanderZ]

try

DEFINE_ADJUST(calc,domain)
{

face_t f;
Thread *t;
real mf_co,mf_co2;/* variable declaration */
real c_co,c_co2;/* variable declaration */

int boundaryID=1; /*wall ID*/
thread_loop_f(t,domain)
{
if (THREAD_ID(t)==boundaryID)
{
begin_f_loop(f,t)
{

mf_co=F_YI(f, t, 3);
mf_co2=F_YI(f, t, 4);

conc_co=mf_co*F_R(f, t);

C_UDMI(F_C0(f,t),THREAD_T0(t),0)=-0.0092976*c_co;
}
end_f_loop(f,t)
}
Message0("\n\n UDF DONE \n\n");
}
}

DEFINE_SOURCE(CO_source,c,t,dS,eqn)
{
real source;
source = C_UDMI(c,t,0);
dS[eqn] = 0.0;
return source;
}

best regards

[sooraj546]

thanks a lot for replying,

the highlighted step below has been changed by you to
source = C_UDMI(c,t,0);

But in reality the wall boundary flux is stored in C_UDMI(F_C0(f,t),THREAD_T0(t),0)=-0.0092976*c_co;

Kindly help me out.........as i am unsure about................... how to call this memory argument C_UDMI(F_C0(f,t),THREAD_T0(t),0)"


DEFINE_SOURCE(CO_source,c,t,dS,eqn)
{
real x[ND_ND];
real source;
source = C_UDMI(F_C0(c,t),THREAD_T0(t),0);
dS[eqn] = 0.0;

return source;
}
so is this representation correct?

[AlexanderZ]

not correct

source = C_UDMI(c,t,0);

is correct

Read about C_UDMIs in Ansys Fluent Customization manual

best regards

[sooraj546]

thanks a lot for that reply

[sooraj546]

when i add the adjust function its working and displaying msg UDF done etc but when i add the source term..........its hows the error as shown below.

I cant resolve it. Kindly help me out

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

Node 0: Process 2956: Received signal SIGSEGV.

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

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

Node 1: Process 13268: Received signal SIGSEGV.

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

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

Node 2: Process 4248: Received signal SIGSEGV.

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

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

Node 3: Process 3152: Received signal SIGSEGV.

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

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

[AlexanderZ]

what did you put in source?

best regards

[sooraj546]

DEFINE_ADJUST(calc,domain)
{

face_t f;
Thread *t;
real mf_co;/* variable declaration */
real c_co;/* variable declaration */

int boundaryID=1; /*wall ID*/
thread_loop_f(t,domain)
{
if (THREAD_ID(t)==boundaryID)
{
begin_f_loop(f,t)
{
mf_co=F_YI(f, t, 3);
c_co=mf_co*F_R(f, t);
C_UDMI(F_C0(f,t),THREAD_T0(t),6)=-0.0092976*c_co;
}
end_f_loop(f,t)
}
Message0("\n\n UDF DONE \n\n");
}
}

DEFINE_SOURCE(CO_source,c,t,dS,eqn)
{
real source;
source = C_UDMI(c,t,6);
dS[eqn] = 0.0;
return source;
}

this is the code there is nothing much in it to cause any big problem. My domain is just a sphere where all the volumetric reactions are happening thats all

[AlexanderZ]

did you allocate 7 UDMS in fluent gui?

go to user defined -> Memory -> number of UDM Locations -> set 7 (at least)

best regards

[sooraj546]

yes sir..................really sorry the error i am getting is
I cant resolve it. Kindly help me out

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

Node 0: Process 2956: Received signal SIGSEGV.

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

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

Node 1: Process 13268: Received signal SIGSEGV.
not segmentation fault

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

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

Node 2: Process 4248: Received signal SIGSEGV.

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

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

Node 3: Process 3152: Received signal SIGSEGV.

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

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

[sooraj546]

Is this because i am attaching C_UDMI(F_C0(f,t),THREAD_T0(t),6) i.e face into source which is kg/m3 etc............... ?

[AlexanderZ]

i dont think so, make a contour of UDMI_6, what are max min values?
best regards

[sooraj546]

F_YI(f, t, 3),F_R(f, t)
These two are the problem as its working when i give
C_UDMI(F_C0(f,t),THREAD_T0(t),6)=-0.0092976 its running fine

but when i introduce C_UDMI(F_C0(f,t),THREAD_T0(t),6)=-0.0092976*F_YI(f, t, 3)*F_R(f, t);
Updating solution at time level N... done.
iter continuity x-velocity y-velocity z-velocity energy fe3o4 feo fe co co2 c time/iter

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

Node 0: Process 6044: Received signal SIGSEGV.

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

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

Node 1: Process 3788: Received signal SIGSEGV.

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

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

Node 2: Process 11644: Received signal SIGSEGV. this error comes what to do.?

[AlexanderZ]

check what you get you get using F_YI(f, t, 3) and F_R(f, t) using UDMs

best regards

[sooraj546]

ok sir thanks a lot for ur reply

[sooraj546]

the F_YI(f, t, 3) is varying in an increasing pattern shown below and F_R(f, t) varying in an decreasing pattern similarly but dnt know y the overall code is not working.
C_UDMI(F_C0(f,t),THREAD_T0(t),6)=0.0092976*F_YI(f, t, 3) its running fine

but when i introduce C_UDMI(F_C0(f,t),THREAD_T0(t),6)=0.0092976*F_YI(f, t, 3)*F_R(f, t); still not working same error exits.
simlarly when i use C_UDMI(F_C0(f,t),THREAD_T0(t),6)=0.0092976*F_R(f, t); not working same error exits.

so the problem is with F_R(f, t)
what to do

[sooraj546]

there is a warning suggesting

.c(101) warning C4002: too many actual parameters for macro 'F_R'

when i use

C_UDMI(F_C0(f,t),THREAD_T0(t),6)=3*0.00972*F_YI(f, t, 3)*1000*F_R(f,t)/12; line 101

any suggestions sir?

[AlexanderZ]

i dont see any problems in line

C_UDMI(F_C0(f,t),THREAD_T0(t),6)=3*0.00972*F_YI(f, t, 3)*1000*F_R(f,t)/12;

jowever, you may try to create additional variables for F_YI(f, t, 3) and F_R(f,t)

real species_mass_fraction, my_rho;
cell_t *c0;
Thread t0;

....
species_mass_fraction = F_YI(f, t, 3);
my_rho = F_R(f,t);
c0 = F_C0(f,t);
t0 = THREAD_T0(t);
C_UDMI(c0,t0,6)=3*0.00972*species_mass_fraction*1000*my_rho/12;

[sooraj546]

same error is coming up sir. Is there any other way of getting individual species density

[sooraj546]

thanks a lot everyone.........I have solved it in a different way