[AlexanderZ]

first if all try fixed code

#include "udf.h"

real tavg_abr = 286.5;
real UDSavg_abr = 0.007;
real sensor_temperature = 315.15;
int if_number = 0;

/* Obtain the mean temperature at the location of thermocouple */
/* Thermocouple located at coordinates (x,y,z) = (0.0,0.0,1.5) */
DEFINE_EXECUTE_AT_END(tsensor)
{
real x[ND_ND];
real xc,yc,zc,nt;

cell_t c;
Domain *d;
Thread *t;
d = Get_Domain(1);
nt=0.0;

thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
C_CENTROID(x,c,t);

xc = x[0];
yc = x[1];
zc = x[2];

if ((xc >= 0.0) && (xc <= 0.35))
{
if ((yc >= 0.0) && (yc <= 0.35))
{
if ((zc >= 1.5) && (xc <= 1.85))
{
sensor_temperature = sensor_temperature + C_T(c,t); /* temperature is obatined at each iteration */
nt=nt+1.0; /* number of iterations */
}
}
}
}
end_c_loop(c,t)
}
sensor_temperature /= nt; /* Avg temperature after each timestep */

Message0 ("xc = %f\n",xc);
Message0 ("yc = %f\n",yc);
Message0 ("zc = %f\n",zc);
Message0 ("nt = %f\n",nt);
Message0("sensor_temperature = %f\n",sensor_temperature);

}
DEFINE_EXECUTE_AT_END(avg_inlet_tempandUDS)
{

int ID = 8;
Domain *d;
face_t f;
real area[ND_ND];
real a;
real area_tot = 18.72;
Thread *tf;
d = Get_Domain(1);
tf = Lookup_Thread(d,ID);
begin_f_loop(f,tf)
{
F_AREA(area,f,tf);
a = NV_MAG(area);
area_tot += a;
tavg_abr += F_T(f,tf)*a; /* inlet face temperature from ID = 8 is taken to compute the avg inlet temp */
UDSavg_abr += F_UDSI(f,tf,0)*a; /* inlet face scalar quantity from ID = 8 is taken to compute the avg inlet scalar quantity */
}
end_f_loop(f,tf)

#if RP_NODE
area_tot = PRF_GRSUM1(area_tot);
tavg_abr = PRF_GRSUM1(tavg_abr);
UDSavg_abr = PRF_GRSUM1(UDSavg_abr);
#endif
tavg_abr /= area_tot;
UDSavg_abr /= area_tot;
Message0("tavg_abr = %f UDSavg_abr = %f area_tot = %f\n",tavg_abr, UDSavg_abr, area_tot);
}
DEFINE_PROFILE(velocity,t,i)
{
real velocity;
face_t f;
if (tavg_abr <= sensor_temperature && UDSavg_abr < 0.03)
{
velocity = 0.051;
if_number++;
}
else
{
velocity = 0.0;
}
begin_f_loop(f,t)
{
F_PROFILE(f,t,i) = velocity;
}
end_f_loop(f,t)
}
DEFINE_ON_DEMAND(get_if_number)
{
Message0("******** int if_number = %d **************\n",if_number);
}

if you still have wrong output, that you should change the way, you apply boundary conditions
you should add to your UDF reading from file or hardcopy these data in UDF explicitly

[Shubhamp]

Hello Alexander,
Thanks for your suggestions. I compiled and ran the code incorporating your suggestions but the coordinate values are not what is expected (0,0,1.5). Could you please suggest any more corrections?
Below is the attached code with the output. Thanks

#include "udf.h"
real sensor_temperature = 315.15

DEFINE_EXECUTE_AT_END(tsensor)
{

real x[ND_ND];
real xc,yc,zc,nt;

cell_t c;
Domain *d;
Thread *t;
d = Get_Domain(1);
nt=0.0;
/* Begin loop to determine the temperature at the centroid of cells near the thermocouple */
thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
C_CENTROID(x,c,t);

xc = x[0];
yc = x[1];
zc = x[2];

if ((xc >= 0.0) && (xc <= 0.35))
{
if ((yc >= 0.0) && (yc <= 0.35))
{
if ((zc >= 1.5) && (xc <= 1.85))
{
sensor_temperature = sensor_temperature + C_T(c,t);
nt=nt+1.0;
}
}
}
}
end_c_loop(c,t)

}
sensor_temperature /= nt;

Message0 ("xc = %f\n",xc);
Message0 ("yc = %f\n",yc);
Message0 ("zc = %f\n",zc);
Message0 ("nt = %f\n",nt);
Message0("sensor_temperature = %f\n",sensor_temperature);

}

Output:
xc = -2.738164
yc = 1.462940
zc = 4.978388
nt = 0.000000
sensor_temperature = inf

[AlexanderZ]

was

if ((zc >= 1.5) && (xc <= 1.85))

tobe

if ((zc >= 1.5) && (zc <= 1.85))

read your code

[Shubhamp]

Hello Alexander,
Thanks for pointing the typo error. I compiled the corrected code but am receiving the same output. Below are the attached code and the output.Thanks

#include "udf.h"
real sensor_temperature = 315.15

DEFINE_EXECUTE_AT_END(tsensor)
{

real x[ND_ND];
real xc,yc,zc,nt;

cell_t c;
Domain *d;
Thread *t;
d = Get_Domain(1);
nt=0.0;
/* Begin loop to determine the temperature at the centroid of cells near the thermocouple */
thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
C_CENTROID(x,c,t);

xc = x[0];
yc = x[1];
zc = x[2];

if ((xc >= 0.0) && (xc <= 0.35))
{
if ((yc >= 0.0) && (yc <= 0.35))
{
if ((zc >= 1.5) && (zc <= 1.85))
{
sensor_temperature = sensor_temperature + C_T(c,t);
nt=nt+1.0;
}
}
}
}
end_c_loop(c,t)

}
sensor_temperature /= nt;

Message0 ("xc = %f\n",xc);
Message0 ("yc = %f\n",yc);
Message0 ("zc = %f\n",zc);
Message0 ("nt = %f\n",nt);
Message0("sensor_temperature = %f\n",sensor_temperature);

}

Output:
xc = -2.738164
yc = 1.462940
zc = 4.978388
nt = 0.000000
sensor_temperature = inf

[AlexanderZ]

it is possible to see
xc = -2.738164
yc = 1.462940
zc = 4.978388
if your domain is big enough, check it
because
Message0 ("xc = %f\n",xc);
Message0 ("yc = %f\n",yc);
Message0 ("zc = %f\n",zc);
show last coordinates from loop, there is no reason for coordinates to be filtered by if statment

nt = 0.000000
sensor_temperature = inf
sensor_temperature = inf because you have sensor_temperature /= nt; where nt=0

nt=0 could be only if code never goes inside if statement, check why
check your domain and dimensons

[Shubhamp]

Hello Alexander,
I have changed the code now and after compilation am getting the desired output. But am not sure if this approach is correct or not. I think it is just pasting the value of the global variable and the coordinate values. Could you please have a look at it? Thanks

#include "udf.h"
real sensor_temperature = 315.15

DEFINE_EXECUTE_AT_END(tsensor)
{

real x[ND_ND];
real xc,yc,zc,nt;

cell_t c;
Domain *d;
Thread *t;
d = Get_Domain(1);


thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
C_CENTROID(x,c,t);

xc = 0.00000;
yc = 0.00000;
zc = 1.50000;



if (x[0] = xc)
{
if (x[1] = yc)
{
if ( x[2] = zc)
{
sensor_temperature = C_T(c,t);

}
}
}
}
end_c_loop(c,t)

}


Message0 ("xc = %f\n",xc);
Message0 ("yc = %f\n",yc);
Message0 ("zc = %f\n",zc);

Message0("sensor_temperature = %f\n",sensor_temperature);

}

Outcome before first iteration:
xc = 0.000000
yc = 0.000000
zc = 1.500000
sensor_temperature = 315.150000
step flow-time report-def-0 report-def-0
0 0.0000e+00 0.0000e+00 3.5944e-01

Outcome after first solution convergence:
xc = 0.000000
yc = 0.000000
zc = 1.500000
sensor_temperature = 315.150000
step flow-time report-def-0 report-def-0 flow-time
1 2.0000e+00 -9.5503e-01 9.5472e-01 2.0000e+00
Flow time = 2s, time step = 1

[AlexanderZ]

this is wrong

if (x[0] = xc)
{
if (x[1] = yc)
{
if ( x[2] = zc)
{
sensor_temperature = C_T(c,t);

}
}
}

at least you must use == to compare
but with x[0] == xc you will never get true, because exact match has very low chance

use previous code

in FLuent GUI go to General -> check -> in console you will get information of your domain
show it, especially Domain Extents

[Shubhamp]

Hello alexander,
Below is the attached domain parameters for your reference:

Domain Extents:
x-coordinate: min (m) = -6.400000e+00, max (m) = 6.400000e+00
y-coordinate: min (m) = -6.399987e+00, max (m) = 6.399991e+00
z-coordinate: min (m) = 0.000000e+00, max (m) = 1.236673e+01
Volume statistics:
minimum volume (m3): 2.110109e-09
maximum volume (m3): 1.220315e-02
total volume (m3): 1.380014e+03
Face area statistics:
minimum face area (m2): 2.388706e-06
maximum face area (m2): 1.069415e-01

I was having a look at a udf macro: CX_Find_Cell_With_Point: problem

It was mentioned that to first locate the allotted coordinate in the domain and then find out the associated cell centroid followed by acquiring its variable. Is it of any help to incorporate it into the above code?
Thanks

[AlexanderZ]

in my case code from January 8 works well
seems like your mesh has huge elements
so no element is inside
if ((xc >= 0.0) && (xc <= 0.35))
{
if ((yc >= 0.0) && (yc <= 0.35))
{
if ((zc >= 1.5) && (xc <= 1.85))

but it's hard to imagine

[Shubhamp]

In my case, the element size is 350 mm with skewness metrics of 0.7. For such a large domain I had already carried out the mesh independency test and came down to 350 mm. Any suggestions to fit the current code in the domain?

Thanks

[Shubhamp]

I have also tried changing the xc, yc and zc limits but it is giving the same output as mentioned below:

Output:
xc = -2.738164
yc = 1.462940
zc = 4.978388
nt = 0.000000
sensor_temperature = inf

[AlexanderZ]

element size is 350mm?
what are you going to get with this mesh?
I've never saw something like this....

but, lets assume, that it is correct, change code to following:

if ((xc >= -0.4) && (xc <= 0.4))
{
if ((yc >= -0.4) && (yc <= 0.4))
{
if ((zc >= 1.2) && (xc <= 1.9))

so 1 element will be inside these boundaries 100%

[Shubhamp]

Hello alexander,
I incorporated your suggestion but am receiving the same output whatsoever be the limits of the xc, yc and zc. Should i export the coordinates of node or cell center of the domain and figure out a close range and then check out the code?
And i have arrived at this mesh size by performing mesh independency tests with temperature and courant number. So it is quite reasonable for my model case.
Thanks

[AlexanderZ]

how you can check, how many cells are inside your if statement:
in fluent gui go to ADAPT-> Mark/Adapt cells -> Region
put there your coordinates, press MARK
push Manage button here, select the region and press Display.

find coordinates that will select as many cells as you need

[Shubhamp]

Hello,
I followed your directions and with the designated limits of x,y, and z coordinates below:
if ((xc >= -0.4) && (xc <= 0.4))
{
if ((yc >= -0.4) && (yc <= 0.4))
{
if ((zc >= 1.2) && (zc <= 1.9))
The GUI showed 93 cells. Then I took the coordinates of two farthest ends and ran the simulation. But it is showing the same output.

#include "udf.h"
real sensor_temperature = 315.15

DEFINE_EXECUTE_AT_END(tsensor)
{

real x[ND_ND];
real xc,yc,zc,nt;

cell_t c;
Domain *d;
Thread *t;
d = Get_Domain(1);
nt=0.0;
/* Begin loop to determine the temperature at the centroid of cells near the thermocouple */
thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
C_CENTROID(x,c,t);

xc = x[0];
yc = x[1];
zc = x[2];

if ((xc >= -0.468547) && (xc <= 0.493969))
{
if ((yc >= -0.51177) && (yc <= 0.428963))
{
if ((zc >= 1.34611) && (zc <= 1.59948))
{
sensor_temperature = sensor_temperature + C_T(c,t);
nt=nt+1.0;
}
}
}
}
end_c_loop(c,t)

}
sensor_temperature /= nt;

Message0 ("xc = %f\n",xc);
Message0 ("yc = %f\n",yc);
Message0 ("zc = %f\n",zc);
Message0 ("nt = %f\n",nt);
Message0("sensor_temperature = %f\n",sensor_temperature);

}

output:
xc = -2.738164
yc = 1.462940
zc = 4.978388
nt = 0.000000
sensor_temperature = inf
step flow-time report-def-0 report-def-0 flow-time
1 2.0000e+00 -9.5503e-01 9.5472e-01 2.0000e+00

I have also tried with:
begin_c_loop_int(c,t)
..
end_c_loop_int(c,t)
and its "ext" counterpart but recieving the following output:
xc = -0.469403
yc = 0.800998
zc = 0.450407
nt = 0.000000
sensor_temperature = inf
tavg_abr = 19.521501 UDSavg_abr = 0.000455 area_tot = 299.520000
step flow-time report-def-0 report-def-0 flow-time
1 2.0000e+00 -9.5503e-01 9.5472e-01 2.0000e+00

The if-condition is not getting into the code. Does it gets affected by parallel consideration? Your suggestions are highly required.
Thanks

[AlexanderZ]

you may try to add this before sensor_temperature /= nt; line

# if RP_NODE /* Perform node synchronized actions here
Does nothing in Serial */
nt = PRF_GRSUM1(nt);
sensor_temperature = PRF_GRSUM1(sensor_temperature);
# endif /* RP_NODE */

[Shubhamp]

Hello,
Thanks for the suggestions, Alexander. The nt and sensor_temperature are all good now. However, the coordinate values are not as desired. Is there any other reason why it is so? Thanks

#include "udf.h"
real sensor_temperature = 315.15

DEFINE_EXECUTE_AT_END(tsensor)
{

real x[ND_ND];
real xc,yc,zc,nt;
real sensor_temperature = 0.0; /* had to re-initialize again otherwise the sensor_temperature value was increasing after each timestep.*/
cell_t c;
Domain *d;
Thread *t;
d = Get_Domain(1);
nt=0.0;

thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
C_CENTROID(x,c,t);

xc = x[0];
yc = x[1];
zc = x[2];

if ((xc >= -0.468547) && (xc <= 0.493969))
{
if ((yc >= -0.51177) && (yc <= 0.428963))
{
if ((zc >= 1.34611) && (zc <= 1.59948))
{
sensor_temperature = sensor_temperature + C_T(c,t);
nt=nt+1.0;
}
}
}
}
end_c_loop(c,t)

}
# if RP_NODE
nt = PRF_GRSUM1(nt);
sensor_temperature = PRF_GRSUM1(sensor_temperature);
# endif
sensor_temperature /= nt;

Message0 ("xc = %f\n",xc);
Message0 ("yc = %f\n",yc);
Message0 ("zc = %f\n",zc);
Message0 ("nt = %f\n",nt);
Message0("sensor_temperature = %f\n",sensor_temperature);

}

output:
xc = -2.738164
yc = 1.462940
zc = 4.978388
nt = 61.000000
sensor_temperature = 315.150000

[AlexanderZ]

what you want from these coordinates?
you have a loop of cells, each cell has its own coordinates, but you return coordinates once

you may put
xc = x[0];
yc = x[1];
zc = x[2];
inside if statement to get coordinates of last cell inside your box

[Shubhamp]

Hello, alexander,
The coordinate range that I have used denotes the sensor location. So I want the temperature of the cells averaged in that range only to act as a control unit for the inlet parameters. In this case, how can I be sure that the sensor_temperature that I am getting is the temperature in the given coordinate range? In addition, shouldn't the code show the last coordinate that must be within the given range? Your suggestions are highly required.
Thanks

[AlexanderZ]

you may put
xc = x[0];
yc = x[1];
zc = x[2];
inside if statement to get coordinates of last cell inside your box