# Changing boundary condition at pressure outlet using udf

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 November 5, 2014, 00:59 Changing boundary condition at pressure outlet using udf #1 New Member   AJK Join Date: Nov 2014 Posts: 6 Rep Power: 2 Hi, i am doing MTech project in cfd analysis and in need of urgent help. I am using fluent to solve this problem. Following is my problem: 1. A simple assemby with 1 inlet and 2 outlets. With a fan near to the inlet. 2. I need to find pressure acting on the blade of the fan, in case one of the outlet is closed. 3. My issue over here is to close and open the output with respect to time. 4. I wanted to know could it be done by UDF. 5. Or any other method which could be used. I want the change to take place with respect to time. It would be very kind of you if you could help me out. Thanks and regards....

 November 5, 2014, 07:20 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 10,823 Rep Power: 85 Yes it can be done by a UDF. But try the Fluent forum if you want to find out how.

 November 5, 2014, 08:07 #3 New Member   AJK Join Date: Nov 2014 Posts: 6 Rep Power: 2 Could you provide me with link. I am new to UDF.

 November 5, 2014, 16:03 #4 New Member   AJK Join Date: Nov 2014 Posts: 6 Rep Power: 2 #include "udf.h" DEFINE_PROFILE(unsteady_pressure, thread, position) { face_t f; real t = CURRENT_TIME; if((t>=5 && t<=10)) { begin_f_loop(f, thread) { F_PROFILE(f, thread, position) = 0; } end_f_loop(f, thread) } } Following was the UDF I used but it doesn't seem to affect the fluid flow as pressure outlet is zero. Please anybody could help out.

November 6, 2014, 01:59
#5
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Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,823
Rep Power: 85
Quote:
 But try the Fluent forum if you want to find out how.
http://www.cfd-online.com/Forums/fluent/

 November 7, 2014, 05:14 #6 New Member   AJK Join Date: Nov 2014 Posts: 6 Rep Power: 2 Thank you for the help

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