concentration gradient
 

hello
i enter mass transfer equation by using uds
and at inlet boundary condition i want concentration gradient that i enter it with a udf
but when i see concentration gradient at inlet in graphics its not correct
for example top of it must be red color but its green
what should i do

Your UDF is not doing what you expect. You have two possibilities:

1. Change your expectations.
2. Change your UDF.

Can you say me the udf that i should use

Can you give me the UDF that you used, then maybe I can explain why it is not doing what you expect.

#include "udf.h"


DEFINE_PROFILE(inlet_concentration, face_thread, i)
{
face_t face;
real r[ND_ND];



begin_f_loop(face,face_thread)
{
F_CENTROID(r, face, face_thread);
F_PROFILE(face, face_thread, i) = 3.3*100000*r[1]+5;
}
end_f_loop(face,face_thread)

}

Is it just a simply interpolation and graphical bug? In your UDF you specify face values, but you selected node values in the graphics. Your UDF doesn't specify the values at the other boundaries, the other walls?

first question:yes
once i didnt select node values but the result was not ok
second question: no

And how do you apply this UDF? Exactly which property is set to this UDF in Fluent?

To speed things up: what do you want your gradient to be?

If you want it to be 3.3*100000, you are doing it the wrong way...