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udf for Temperature profile

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Old   November 27, 2008, 09:01
Default udf for Temperature profile
  #1
Ralf
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Hi!

i have a solid, and i would like to define an initial temperature profile for cooling calculation in x direction (a polynom) - in y direction, the temp. should be constant.

I have created follwing UDF, but somehow, it does not work...

Maybe there is something with the units? my mesh is created in mm. the solid is 100 mm long and there should be a temp. drop at the end to 960K.

Any idea? Ralf

#include "udf.h"

DEFINE_PROFILE(start_temperature,thread,index)

{

real y[ND_ND];

real x;

face_t f;

begin_f_loop(f,thread)

{

F_CENTROID(y,f,thread);

x = y[1];

F_PROFILE(f,thread,index) = 277103.*x*x*x -64574.*x*x + 2416.*x + 1099.;

} end_f_loop(f,thread)

}
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Old   November 27, 2008, 13:02
Default Re: udf for Temperature profile
  #2
bohis
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I guess there should be should be 0 instead of 1. I mean this: x = y[0];
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Old   November 28, 2008, 04:36
Default Re: udf for Temperature profile
  #3
Ralf Schmidt
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yes!! that's it!! now, it works!!

thanks a lot!

For me, without c+ knowledge, it is rather difficult to understand these udf, also the udf manual is not very helpful for these problems...

Ralf
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Old   November 28, 2008, 05:31
Default Re: udf for Temperature profile
  #4
Rogerio Fernandes Brito
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I think u must do 2 UDF´s and not only one. One for x and other for y. Then, u can input the direction of your temperature field, as u do with velocity components.

Why did u use "x = y[1];"?
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Old   November 28, 2008, 07:35
Default Re: udf for Temperature profile
  #5
Ralf
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Hi,

the udf works for my 2d. model. Attached for completeness the udf.

T = x*x*x*277103. -x*x*64574. + x*2416. + 1099. is the polynome, that describes the Temp. distribution (x in m !!!)

Thanks you for your help!!!

Ralf

-----------------------

#include "udf.h"

DEFINE_PROFILE(start_temperature,thread,index)

{

real y[ND_ND];

real x;

cell_t c;

begin_c_loop(c,thread)

{

C_CENTROID(y,c,thread);

x = y[0];

F_PROFILE(c,thread,index) = x*x*x*277103. -x*x*64574. + x*2416. + 1099.;

}

end_c_loop(c,thread)

}
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Old   December 6, 2008, 02:42
Default ask an question about udf for Temperature profile
  #6
lucy
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Ralf, your UDF "DEFINE_PROFILE(start_temperature,thread,index ) "for initialize temperature,not for boundary condition? lucy
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