# UDF temperature profile

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 October 10, 2011, 10:29 UDF temperature profile #1 New Member   Delmas Anthony Join Date: Oct 2011 Posts: 3 Rep Power: 7 Hello all, My question will maybe seem quite easy for some of you, but i've never used UDF before and i'm a little lost, especialy cause i don't know either how to code in this language. Anyway, to make short, i have the temperature values of a wall surface, obtained experimentatly. Now i would like to implement them in the simulation. I have for ex: x=0.1cm T=350K x=0.2cm T=367K x=0.3cm T=389K.... How can i put all these values in my simulation via UDF? Thanks all for your future helps.

 January 9, 2012, 06:11 #2 New Member   Join Date: Dec 2009 Location: Italy Posts: 23 Rep Power: 9 Hi Anthony, I also have to specify the temperature profile (fixed in time) at a wall and do not know how... how did you solve the problem? Might you copy the udf file you wrote to specify wall temperature? Thank you very much!! Serse

 January 9, 2012, 06:41 #3 Senior Member     Flavio Join Date: Sep 2011 Location: Brescia, Italy Posts: 181 Rep Power: 7 I would insert a Profile rather than an UDF. try it!

 January 9, 2012, 09:10 #4 New Member   Delmas Anthony Join Date: Oct 2011 Posts: 3 Rep Power: 7 I solved the problem by finding the polynomial equation feeting with my points. I found this equation with Matlab.

 January 13, 2012, 13:33 #5 New Member   Join Date: Dec 2009 Location: Italy Posts: 23 Rep Power: 9 I tried with the following profile file to simulate a linearly increasing temperature at a wall ((temperature line 2) (x -0.3955 0.682 ) (y 0.0795 0.0795 ) (temperature 1173.15 1923.15 ) ) The file simply contains locations of two nodes and temperature values at these nodes. Fluent reads it easily, but after initializing the solution there is not such temperature distribution at the wall. The temperature I get is the one from the fluid zone. Might you help me on this? For NeoGamaes - How did you include the polynomial function at a wall? Thank you very much!

 January 16, 2012, 04:10 #6 New Member   Delmas Anthony Join Date: Oct 2011 Posts: 3 Rep Power: 7 Exemple of Temperature profile: Code: ```/*************************************************************************/ /* temperature_profile2_100.c */ /* UDF for specifying a temperature profile boundary condition for the disk */ /*************************************************************************/ #include "udf.h" DEFINE_PROFILE(temperature100disk, thread, index) { real x[ND_ND]; /* this will hold the position vector */ real y; face_t f; begin_f_loop(f, thread) { F_CENTROID(x,f,thread); y = x[1]; F_PROFILE(f, thread, index) = (-3363080951743./1000000000)*y*y+(426743./10000)*y+(3710751./10000); } end_f_loop(f, thread) }``` If your wall is horizontal in Fluent, you just have to replace x by y. To find the polynomial function with Matlab, use the "polyfit" and "polyval" function.. it's really easy.

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