[kamu123]

Hello i have a question about setting the location with boundary condition ID

I have divided two section as A-B, B-C with boundary A,B,C.

As original code, i set the boundary A,B,C with coordinate directly.


Original Code
================================
#define A 6.
#define B A+5.
#define C B+4.


DEFINE_SOURCE(xmom_src,c,t,dS,eqn)
{
int body;
double src,x[ND_ND],loc,source;

body=0;
C_CENTROID(x,c,t);
loc=x[0];

if ((loc > A) && (loc <= B)) body = 1;
else if ((loc > B) && (loc <= C)) body = 2;

switch (body)
{
case 1:
src = 1/p;
source = -src*C_U(c,t);
dS[eqn] = -src;
break;
case 2:
src = 1/p;
source = -src*C_U(c,t);
dS[eqn] = -src;
break;
default:
source = 0.;
dS[eqn] = 0.;
}
return source;
}

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

Now the boundary "B" is changed as the curved face.

So i have to use the boundary condition ID.

I have checked from BC panel and the ID of B was 191.

From here, please anyone check my code.

I am confusing where should be changed

Changed code is shown below
===================================
Changed code

#define A 6.
#define C A+9.


DEFINE_SOURCE(xmom_src,c,t,dS,eqn)
{
int body;
double src,x[ND_ND],loc,source;

body=0;
C_CENTROID(x,c,t);
loc=x[0];

int ID = 191; /* Zone ID for top from Boundary Conditions task page */
Thread *B;
B = Lookup_Thread(d, ID);

if ((loc > A) && (loc <= B)) body = 1;
else if ((loc > B) && (loc <= C)) body = 2;

switch (body)
{
case 1:
src = 1/p;
source = -src*C_U(c,t);
dS[eqn] = -src;
break;
case 2:
src = 1/p;
source = -src*C_U(c,t);
dS[eqn] = -src;
break;
default:
source = 0.;
dS[eqn] = 0.;
}
return source;
}
=================================

[AlexanderZ]

variable loc is coordinate along x axis, so you should define start/end of AB BC as x coordinate

recommendation: do not use double type in UDF, use real instead

best regards

[kamu123]

hello AlexanderZ

That's what i am asking now.

start/end of AB BC was x coordinate.

But now i can not set B as x coordinate because it is curved

I just tried changing only B as domain ID

And then do i have to change the whole variable loc?

[AlexanderZ]

curved line is 2d line, so you need bouch x and y axis to define it.
for your case loc_x =x[0]; loc_y = x[1];

looks like you need to change your if statement

best regards