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Temperature gradient macros on face

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Old   January 9, 2010, 04:54
Default Temperature gradient macros on face
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qwerty753
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How to obtain a temperature gradient directly from the solver for the UDF purposes? Does any macro exist to compute temperature gradient on a face?
my aim i to extract heat flux on a face!
Thank you
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Old   March 9, 2010, 00:54
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Quote:
Originally Posted by qwerty753 View Post
How to obtain a temperature gradient directly from the solver for the UDF purposes? Does any macro exist to compute temperature gradient on a face?
my aim i to extract heat flux on a face!
Thank you
If your face is a wall boundary, then use WALL_HEAT_FLUX(face_t f,Thread*tf) to directly report the heat flux
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Old   March 11, 2010, 08:35
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Thanks, but i don't need of a heat flux, i want to know dt/dn i.e. gradient.
Bye.
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Old   March 12, 2010, 01:08
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Quote:
Originally Posted by qwerty753 View Post
How to obtain a temperature gradient directly from the solver for the UDF purposes? Does any macro exist to compute temperature gradient on a face?
my aim i to extract heat flux on a face!
Thank you
You can define a UDS. loop over all the cells and let its UDS value equal to the temperature gradient , C_UDSI(c,t,0)=C_T_G(c,t).
Then use the UDS gradient on cell, distance vector to compute the temperature gradient on face.

#include "udf.h"
DEFINE_ON_DEMAND(test)
{
face_t f;
cell_t c0;
Thread *tf,*t0;
Domain*domain=Get_Domain(1);
real NV_VEC(dist_vector);
real f_centoid[ND_ND],c_centroid[ND_ND];
real face_value,cell_value;
thread_loop_f(tf, domain)/* loops over all face threads in a domain*/
{
begin_f_loop(f, tf) /* loops over faces in a face thread */
{
F_CENTROID(f_centoid,f,tf); //centroid of a face
c0=F_C0(f,tf);
t0=THREAD_T0(tf);
C_CENTROID(c_centroid,c0,t0); //centroid of the neighbour cell
NV_DD(dist_vector,=,f_centoid[0],f_centoid[1],0,-,c_centroid[0],c_centroid[1],0);
face_value=C_UDSI(c0,t0,0)+NV_DOT(C_UDSI_G(c0,t0,0 ),dist_vector);
cell_value=C_UDSI(c0,t0,0);
Message0("x coord.=%g,face value=%g,cell value=%g\n",f_centoid[0],face_value,cell_value);
}
end_f_loop(f, f_thread)
}
}
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Old   June 16, 2010, 03:38
Default convective boundary condition
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after writing a similar face gradient, i have to give a mass convection boundary condition with the face and air, but i couldn't manage to put the cell (for air) and face (for solid face) together. can you help me?
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Old   March 12, 2013, 08:20
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I am solving a 2D problem. I want to calculate temperature gradient (and also write it) on the surface(line) whose end points I know. Can anyone tell me how to do it
Thank you
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