UDF Help!

littlelz · July 2, 2013, 09:29

I am new on UDF. Just wonder if anybody can help me.

I have an velocity inlet boundary, and an outlet pressure boundary. I need to setup the outlet pressure is a fixed ratio to inlet pressure. As inlet pressure is calculated in running, and the outlet pressure will be varied with it. I am thinking to use UDF to achieve it. But how, I ahev no idea. Could anybody give me some clue. I know how to setup a varied inlet velocity by UDF. thanks

blackmask · July 2, 2013, 21:36

So you are solving the compressible flow problem?
Technically

Code:

DEFINE_EXECUTE_AT_END

along with

Code:

DEFINE_PROFILE

and a file scope variable could do the job, but you need be more concerned on the physical interpretation of the boundary condition as such.

littlelz · July 3, 2013, 05:42

many thanks, blackmask.

I am doing a compressible flow simulation. It is a single fan blade, the pressure ratio is 1.455. That's why I am considering a outlet pressure condition, which will be related to inlet pressure by 1.455. The inlet is velocity inlet boundary. am I right?

July 2, 2013, 09:29	UDF Help!	#1
littlelz New Member Join Date: Mar 2009 Posts: 24 Rep Power: 17	I am new on UDF. Just wonder if anybody can help me. I have an velocity inlet boundary, and an outlet pressure boundary. I need to setup the outlet pressure is a fixed ratio to inlet pressure. As inlet pressure is calculated in running, and the outlet pressure will be varied with it. I am thinking to use UDF to achieve it. But how, I ahev no idea. Could anybody give me some clue. I know how to setup a varied inlet velocity by UDF. thanks

July 2, 2013, 21:36		#2
blackmask Senior Member Join Date: Aug 2011 Posts: 421 Blog Entries: 1 Rep Power: 22	So you are solving the compressible flow problem? Technically Code: DEFINE_EXECUTE_AT_END along with Code: DEFINE_PROFILE and a file scope variable could do the job, but you need be more concerned on the physical interpretation of the boundary condition as such.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Dynamic Mesh UDF	Qureshi	FLUENT	7	March 23, 2017 08:37
Source Term UDF VS Porous Media Model	pchoopanya	Fluent UDF and Scheme Programming	1	August 28, 2013 07:12
UDF parallel error: chip-exec: function not found?????	shankara.2	Fluent UDF and Scheme Programming	1	January 16, 2012 23:14
How to add a UDF to a compiled UDF library	kim	FLUENT	3	October 26, 2011 22:38
UDF, UDF, UDF, UDF	Luc SEMINEL	Main CFD Forum	0	November 25, 2002 05:01

July 3, 2013, 05:42		#3
littlelz New Member Join Date: Mar 2009 Posts: 24 Rep Power: 17	many thanks, blackmask. I am doing a compressible flow simulation. It is a single fan blade, the pressure ratio is 1.455. That's why I am considering a outlet pressure condition, which will be related to inlet pressure by 1.455. The inlet is velocity inlet boundary. am I right?