# heat transfer coefficient for the fluid / solid interface

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 July 7, 2014, 23:38 heat transfer coefficient for the fluid / solid interface #1 Member   sarah Join Date: Aug 2010 Posts: 41 Rep Power: 8 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! guilbemloco likes this.

 July 29, 2014, 10:44 #2 New Member   Join Date: Nov 2013 Posts: 16 Rep Power: 5 Hello: Were you able to solve your problem?

 July 31, 2014, 02:50 #3 Member   sarah Join Date: Aug 2010 Posts: 41 Rep Power: 8 well, I changed some of the statements to constatnt parameter and the it run!

 July 31, 2014, 08:59 #4 New Member   Join Date: Nov 2013 Posts: 16 Rep Power: 5 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.

 July 31, 2014, 14:57 #5 Member   sarah Join Date: Aug 2010 Posts: 41 Rep Power: 8 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

 August 23, 2014, 18:08 udf for heat-transfer-coefficient-fluid-solid-interface #6 New Member   othman Join Date: Aug 2014 Posts: 1 Rep Power: 0 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

 April 25, 2016, 20:50 Udf heat transfer #7 New Member   Junia Mendes Join Date: Apr 2016 Posts: 7 Rep Power: 2 Good night, I'm working with heat transfer and I've had serious problems. Can you help me?

April 26, 2016, 04:59
#8
Senior Member

Bruno Machado
Join Date: May 2014
Posts: 258
Rep Power: 5
Quote:
 Originally Posted by junianatalia 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.

 April 29, 2016, 08:42 My code heat transfer #9 New Member   Junia Mendes Join Date: Apr 2016 Posts: 7 Rep Power: 2 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)

April 29, 2016, 08:48
#10
New Member

Junia Mendes
Join Date: Apr 2016
Posts: 7
Rep Power: 2
Quote:
 Originally Posted by Bruno Machado explain your problem, post the code you wrote and we can try to help you.
Good morning.
Fallow my udf.

Thanks
Attached Files
 heat_udf_1.h (1.1 KB, 17 views) heat_coefficient.c (1.8 KB, 25 views)

 May 12, 2016, 04:40 #11 New Member   gui Join Date: Oct 2013 Posts: 10 Rep Power: 5 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.

 May 12, 2016, 09:58 #12 New Member   gui Join Date: Oct 2013 Posts: 10 Rep Power: 5 Hello Sarah, Could you please show me the UDF you created after you changed some parameters to constant? Thank you

 May 17, 2016, 08:44 #13 New Member   gui Join Date: Oct 2013 Posts: 10 Rep Power: 5 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.

May 17, 2016, 13:12
#14
New Member

Junia Mendes
Join Date: Apr 2016
Posts: 7
Rep Power: 2
Quote:
 Originally Posted by guilbemloco 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

May 18, 2016, 02:27
#15
New Member

gui
Join Date: Oct 2013
Posts: 10
Rep Power: 5
Quote:
 Originally Posted by junianatalia 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
 heat_transfer_coefficient.c (643 Bytes, 3 views)

May 18, 2016, 08:28
#16
New Member

Junia Mendes
Join Date: Apr 2016
Posts: 7
Rep Power: 2
Quote:
 Originally Posted by guilbemloco 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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