# how can i use multiple udfs

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 February 23, 2010, 02:35 how can i use multiple udfs #1 New Member   John Smith Join Date: Feb 2010 Posts: 13 Rep Power: 8 Hello every body as a amateur user of fluent i have a problem when i want to define multiple udf in my case file, my last defined udfs disappeared. How can use multiple udfs in one case file? thank you.

 February 23, 2010, 02:51 Re: how can i use multiple udfs #2 Member   Amol Ramteke Join Date: May 2009 Location: Kolkata Posts: 30 Rep Power: 9 Write all the udf inside same header file for e.g #include "udf.h" DEFINE_PROPERTY(prop, c, t) { } DEFINE_ON_DEMAND(ondemand) { } So on... mozkan26, rasoulb and Shalabh like this.

 February 23, 2010, 03:09 how #3 New Member   John Smith Join Date: Feb 2010 Posts: 13 Rep Power: 8 #include "udf.h" my udf is so: DEFINE_PROFILE(inlet, thread, position) { real pi = 3.1459 ; real P0 = 11208 ; face_t f; real t = CURRENT_TIME; begin_f_loop(f, thread) { t = t - floor(t) ; if ( t>=0.5 ) F_PROFILE(f, thread, position) = P0*sin(pi*t); else F_PROFILE(f, thread, position) = P0*(1.5 - 0.5*cos(2*pi(t-0.5))); } end_f_loop(f, thread) } should i change it ?

 February 23, 2010, 03:13 #4 Member   Amol Ramteke Join Date: May 2009 Location: Kolkata Posts: 30 Rep Power: 9 Could you explain what you want to do.

 February 23, 2010, 03:19 reply #5 New Member   John Smith Join Date: Feb 2010 Posts: 13 Rep Power: 8 I have a pipe that has one inlet and four outlet. the boundary condition for the inlet and outlet in transient pressure. my udf is this transient pressure. now when I interpret the pressure that is used for e.g. out 2 the last interpreted udfs has disappeared.

 February 23, 2010, 03:25 #6 Member   Amol Ramteke Join Date: May 2009 Location: Kolkata Posts: 30 Rep Power: 9 Correct me if im wrong, you would like to give profile to inlet and outlet too. then this udf will not work write separate udf. If not try to compile and hook.

 February 23, 2010, 03:34 explain. #7 New Member   John Smith Join Date: Feb 2010 Posts: 13 Rep Power: 8 let me explain more. I have 5 different udfs for five boundaries . when i define e.g the third one , the two last defined udfs disappeared . ( i mean when i want to specify the boundary condition of the boundaries instead of 5 different udf i just have one .)

 February 23, 2010, 04:39 #8 Member   Amol Ramteke Join Date: May 2009 Location: Kolkata Posts: 30 Rep Power: 9 Where are the five udf above only you are showing one? If you have five udf means write in same file.

 February 23, 2010, 04:45 reply #9 New Member   John Smith Join Date: Feb 2010 Posts: 13 Rep Power: 8 there are almost the same with a few differences in the formula of the pressure . I have written the first udf that is for inlet

 February 23, 2010, 04:47 #10 Member   Amol Ramteke Join Date: May 2009 Location: Kolkata Posts: 30 Rep Power: 9 Yes exactly, the whatever answer i have given first that is true. Put all udf in same file.c ok

 February 23, 2010, 04:51 #11 Member   Amol Ramteke Join Date: May 2009 Location: Kolkata Posts: 30 Rep Power: 9 For eg #include "udf.h" DEFINE_PROFILE(inlet1, thread, position) { your programe; } DEFINE_PROFILE(inlet2, thread, position) { your programe; } DEFINE_PROFILE(inlet3, thread, position) { your programe; } DEFINE_PROFILE(inlet4, thread, position) { your programe; } DEFINE_PROFILE(inlet5, thread, position) { your programe; } Save the file and interprete you will see all the profile and select respectively for the inlet. ok thanks I have work c u 87682111, mumtazcore and Gwench like this.

 February 23, 2010, 07:20 Thanks #12 New Member   John Smith Join Date: Feb 2010 Posts: 13 Rep Power: 8 Thank your lucky stars. Really thank you for your kind helps . c u later.

 June 5, 2016, 21:09 nested if statement in udf #13 New Member   mm Join Date: May 2016 Posts: 24 Rep Power: 2 Respected members I am using udf for defining transient temperature at inlet boundary of my model in fluent. I am writing nested if statement, but model keeps on using the same equation after 180 seconds, and does not move to the next if else statement. My udf is as follows: #include"udf.h" DEFINE_PROFILE(inlet_temperature,thread,position ) { face_t f; begin_f_loop(f,thread) { real t = RP_Get_Real("flow-time"); if ( t <= 100.0 ) F_PROFILE(f,thread,position) = 379.48 + 0.0004*t; else if (100.0 < t <= 180.0 ) F_PROFILE(f,thread,position) = 1.0624*t + 352.0; else if (180.0 < t <= 200.0 ) F_PROFILE(f,thread,position) = 0.2716*t + 494.4; else if (200.0 < t <= 400.0 ) F_PROFILE(f,thread,position) = 328.14*pow(t,0.097); else F_PROFILE(f,thread,position) = 727.82; } end_f_loop(f,thread) } sorry for my poor knowledge of programming. please help me on this error. Thanks.

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