How can I impose variable boundary conditions?

behrang2009 · December 18, 2009, 16:53

Hi Guys!
How can I define variable boundary conditions such as variable temperature on a wall? I believe that I should use UDF. Which parts of the UDF Manual help me most. Any hint?
Thanks
Good luck

dahu007 · December 18, 2009, 20:43

That's right you have ti write an UDF :
I used to do it with the velocity but it should be the same with the temperature. This is an example of a UDF of an unsteady velocity (you can find it in the UDF user guide of Fluent) (in the part boundary counditions and details UDF examples)

/************************************************** ********************
unsteady.c
UDF for specifying a transient velocity profile boundary condition
************************************************** *********************/
#include "udf.h"
DEFINE_PROFILE(unsteady_velocity, thread, position)
{
face_t f;
real t = CURRENT_TIME;
begin_f_loop(f, thread)
{
F_PROFILE(f, thread, position) = 20. + 5.0*sin(10.*t);
}
end_f_loop(f, thread)

}

When your UDF is written you have just to interpret it in Fluent !!!

behrang2009 · December 20, 2009, 21:26

Thanks man.
I have started reading UDF Manual

December 18, 2009, 16:53	How can I impose variable boundary conditions?	#1
behrang2009 Member Behrang Asgharian Join Date: Oct 2009 Posts: 38 Rep Power: 17	Hi Guys! How can I define variable boundary conditions such as variable temperature on a wall? I believe that I should use UDF. Which parts of the UDF Manual help me most. Any hint? Thanks Good luck

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December 18, 2009, 20:43		#2
dahu007 New Member matth Join Date: Aug 2009 Posts: 8 Rep Power: 17	That's right you have ti write an UDF : I used to do it with the velocity but it should be the same with the temperature. This is an example of a UDF of an unsteady velocity (you can find it in the UDF user guide of Fluent) (in the part boundary counditions and details UDF examples) /************************************************ **************** unsteady.c UDF for specifying a transient velocity profile boundary condition ********************************************** ******************/ #include "udf.h" DEFINE_PROFILE(unsteady_velocity, thread, position) { face_t f; real t = CURRENT_TIME; begin_f_loop(f, thread) { F_PROFILE(f, thread, position) = 20. + 5.0sin(10.*t); } end_f_loop(f, thread) } When your UDF is written you have just to interpret it in Fluent !!!

December 20, 2009, 21:26		#3
behrang2009 Member Behrang Asgharian Join Date: Oct 2009 Posts: 38 Rep Power: 17	Thanks man. I have started reading UDF Manual