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heat transfer coefficient for the fluid / solid interface

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Old   July 7, 2014, 23:38
Default heat transfer coefficient for the fluid / solid interface
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sarah
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Hi,
I am using non-equilibrium model in porous zone in Ansys Fluent 14.5. for specifying heat transfer coefficient for the fluid / solid interface, I have written the following udf

#include "udf.h"
DEFINE_PROFILE(Heat_trans_coeff,t,i)
{
cell_t c;
real Nu,Re,Pr;
real dens, visc; /*Fluid*/
real cond, cp; /* Fluid*/
real d_p;
real por;/*Porosity of the bed*/
d_p=0.06;
por=0.36

begin_c_loop(c,t)
{
dens = C_R(c,t); /*Density of fluid*/
visc = C_MU_L(c,t); /*Viscosity fluid*/
cond = C_K_L(c,t); /*Conductivity fluid*/
cp = C_CP(c,t); /*Specific heat fluid*/
Re = ND_MAG(C_U(c,t),C_V(c,t),C_W(c,t))*d_p*dens*por/visc ; /*Reynolds number has been calculated based on pore velocity*/
Pr = cp*visc/cond ;
Nu = 2.+ 1.1 * pow(Re,0.6) * pow(Pr,1./3.);
F_PROFILE(c,t,i) = Nu*cond/d_p ;
}
end_c_loop(c,t)
}
However this code cannot be interpreted in FLUENT. The error message is "c_loop_last: undeclared variable"
I would be grateful if somebody help me!
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Old   July 29, 2014, 10:44
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Hello:

Were you able to solve your problem?
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Old   July 31, 2014, 02:50
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well, I changed some of the statements to constatnt parameter and the it run!
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Old   July 31, 2014, 08:59
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Sarah:
Thanks for your reply. Do you by any chance know how one can get the solid temperature at a specific point in the media by udf?

Thank you.
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Old   July 31, 2014, 14:57
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you're welcome
while you use non equilibrium model , the software creats solid zone itself so you can observe the variation of Temp on that ! also you can create new plane with specific points to see more details.

regards
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Old   August 23, 2014, 18:08
Default udf for heat-transfer-coefficient-fluid-solid-interface
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Dear Pr Sarah

I work on the heat transfer in porous media, and I need a UDF for the heat transfer coefficient fluid/solid that is a function of the solid temperarue and the fluid temperature

Thank's to answer me

Best regards
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Old   April 25, 2016, 20:50
Post Udf heat transfer
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Junia Mendes
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Good night,

I'm working with heat transfer and I've had serious problems. Can you help me?
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Old   April 26, 2016, 04:59
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Quote:
Originally Posted by junianatalia View Post
Good night,

I'm working with heat transfer and I've had serious problems. Can you help me?
explain your problem, post the code you wrote and we can try to help you.
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Old   April 29, 2016, 08:42
Default My code heat transfer
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Junia Mendes
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heat_udf_1.h

It's my code. I'm working with tho phases in Eulerian Model. I'm having trouble describing each stage in my UFD.

The error is pointed out in this line:

heat_kmiec_1980 (c cell_t, Thread * ti, Thread * tj)
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Old   April 29, 2016, 08:48
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Quote:
Originally Posted by Bruno Machado View Post
explain your problem, post the code you wrote and we can try to help you.
Good morning.
Fallow my udf.

Thanks
Attached Files
File Type: h heat_udf_1.h (1.1 KB, 10 views)
File Type: c heat_coefficient.c (1.8 KB, 13 views)
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Old   May 12, 2016, 04:40
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gui
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Dear members of the forum

I need a UDF for the heat transfer coefficient, considering the properties change with the temperature.
My function is very similar to the one Sarah posted here, if anyone knows how to correct that function that would be great!

Thank you,

G

Last edited by guilbemloco; May 12, 2016 at 05:47.
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Old   May 12, 2016, 09:58
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Hello Sarah,

Could you please show me the UDF you created after you changed some parameters to constant?

Thank you
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Old   May 17, 2016, 08:44
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Well, I found that in this code there is a ";" missing after the declaration of "por=0.36".

I added that and I was able to interpret the function normally.
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Old   May 17, 2016, 13:12
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Quote:
Originally Posted by guilbemloco View Post
Well, I found that in this code there is a ";" missing after the declaration of "por=0.36".

I added that and I was able to interpret the function normally.
Hello,

Can you send me your UDF?

Thanks
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Old   May 18, 2016, 02:27
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Quote:
Originally Posted by junianatalia View Post
Hello,

Can you send me your UDF?

Thanks
Sure, it is this:

#include "udf.h"
DEFINE_PROFILE(Heat_trans_coeff,t,i)
{
cell_t c;
real Nu,Re,Pr;
real dens, visc; /*Fluid*/
real cond, cp; /* Fluid*/
real d_p;
real por;/*Porosity of the bed*/
d_p=0.018;
por=0.3;

begin_c_loop(c,t)
{
dens = C_R(c,t); /*Density of fluid*/
visc = C_MU_L(c,t); /*Viscosity fluid*/
cond = C_K_L(c,t); /*Conductivity fluid*/
cp = C_CP(c,t); /*Specific heat fluid*/
Re = ND_MAG(C_U(c,t),C_V(c,t),C_W(c,t))*d_p*dens*por/visc ; /*Reynolds number has been calculated based on pore velocity*/
Pr = cp*visc/cond ;
Nu = 2.+ 1.1 * pow(Re,0.6) * pow(Pr,1./3.);
F_PROFILE(c,t,i) = Nu*cond/d_p ;
}
end_c_loop(c,t)
}

I was able to interpret in windows and to compile in linux systems, the reason is not clear thought.
Attached Files
File Type: c heat_transfer_coefficient.c (643 Bytes, 1 views)
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Old   May 18, 2016, 08:28
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Quote:
Originally Posted by guilbemloco View Post
Sure, it is this:

#include "udf.h"
DEFINE_PROFILE(Heat_trans_coeff,t,i)
{
cell_t c;
real Nu,Re,Pr;
real dens, visc; /*Fluid*/
real cond, cp; /* Fluid*/
real d_p;
real por;/*Porosity of the bed*/
d_p=0.018;
por=0.3;

begin_c_loop(c,t)
{
dens = C_R(c,t); /*Density of fluid*/
visc = C_MU_L(c,t); /*Viscosity fluid*/
cond = C_K_L(c,t); /*Conductivity fluid*/
cp = C_CP(c,t); /*Specific heat fluid*/
Re = ND_MAG(C_U(c,t),C_V(c,t),C_W(c,t))*d_p*dens*por/visc ; /*Reynolds number has been calculated based on pore velocity*/
Pr = cp*visc/cond ;
Nu = 2.+ 1.1 * pow(Re,0.6) * pow(Pr,1./3.);
F_PROFILE(c,t,i) = Nu*cond/d_p ;
}
end_c_loop(c,t)
}

I was able to interpret in windows and to compile in linux systems, the reason is not clear thought.
Thanks! guilbemloco
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