[nonstopthinker]

hey.

I am modelling a coolant flow in a rectangular channel.. I have inlet temperature, top wall temperature, bottom wall temperature, and exit pressure.

i want to define a linear temperature variation for the side walls (i know the top wall and bottom wall temperatures) by means of udf.

kindly help me in writing this code, as i am new to udf. The following is the code i have written. However, i am not getting the correct temperature profile. Please help

# include "udf.h" 
 
DEFINE_PROFILE(tsw, thread, position) 
{ 
real x[ND_ND]; /* this will hold the position vector */ 
real y; 
double y1,y2,tsw; 
int i,j1; 
double yy[1300]; 
real T; 
cell_t c; 
face_t f; 
begin_c_loop(c, thread) 
{ 
    C_CENTROID(x,c,thread); 
        /* temp=C_T(c,thread);*/ 
    for (i=0;i<100;i++) 
    { 
     tsw=264.341*yy[i]+600;} 
    } 
     if (y1>=yy[100]) {tsw=600;} 
    F_PROFILE(c, thread, position) = tsw; 
    /*printf("%f\t%f\t%f\t%f\n",y1,y2,tsw,temp);*/ 
} 
end_c_loop(c, thread) 
}

[Bruno Machado]

Originally Posted by nonstopthinker

hey.

I am modelling a coolant flow in a rectangular channel.. I have inlet temperature, top wall temperature, bottom wall temperature, and exit pressure.

i want to define a linear temperature variation for the side walls (i know the top wall and bottom wall temperatures) by means of udf.

kindly help me in writing this code, as i am new to udf. The following is the code i have written. However, i am not getting the correct temperature profile. Please help

# include "udf.h" 
 
DEFINE_PROFILE(tsw, thread, position) 
{ 
real x[ND_ND]; /* this will hold the position vector */ 
real y; 
double y1,y2,tsw; 
int i,j1; 
double yy[1300]; 
real T; 
cell_t c; 
face_t f; 
begin_c_loop(c, thread) 
{ 
    C_CENTROID(x,c,thread); 
        /* temp=C_T(c,thread);*/ 
    for (i=0;i<100;i++) 
    { 
     tsw=264.341*yy[i]+600;} 
    } 
     if (y1>=yy[100]) {tsw=600;} 
    F_PROFILE(c, thread, position) = tsw; 
    /*printf("%f\t%f\t%f\t%f\n",y1,y2,tsw,temp);*/ 
} 
end_c_loop(c, thread) 
}

What temperature are you getting?

about the code, what is the value of y1? Not defined anywhere.

you can also work your code in something like

if (i <100)
{
...
}
else
{
...
}

I will make it clear and easier.

[D.M]

Hello nonstopthinker,

The question is that why you guys loop over cells to define a specific boundary condition. the name "boundary condition" always make it clear that it is a boundary "face thread" that you are trying to approach not bunch of cells, so maybe change the code like below :

first i have to ask u some questions:
do you have any source of data that "yy" is saved there?? cause yy[0] , yy[1] , ... yy[1300], won't give you anything unless you define values for all the 1300 components of this array called "yy"!
another question! you have used just 101 components of this array "yy" in your code so why giving it 1301 components?!

man i don't see anything in your code that defines values or something for y1 and y2! as i see in your code y2 hasn't been used even once so its better to be removed , and about y1 you must specify it's value like this
"double y1 = 80;" (for example).


#include "udf.h"
static int conter = 0;
DEFINE_PROFILE(temprature, t, i)
{
real x[ND_ND]; /* this will hold the position vector */
double y1,tsw;
double yy[1300];
face_t f;
begin_f_loop(f, t)
{
F_CENTROID(x,f,t);
/* temp=C_T(c,t);*/
for (conter=0;conter<100;conter++)
{
tsw=264.341*yy[conter]+600;}
}
if (y1>=yy[100]) {tsw=600;}
F_PROFILE(f, t, i) = tsw;
/*printf("%f\t%f\t%f\t%f\n",y1,y2,tsw,temp);*/
}
end_f_loop(f, t)
}

and one more thing , the code won't work untill u give values to y1 and yy.