# inlet temp = outlet temp

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 March 6, 2011, 20:42 inlet temp = outlet temp #1 New Member   Join Date: Mar 2011 Posts: 13 Rep Power: 8 Hi, I have an urgent problem with my cfx setup. I am using Ansys 13 CFX Workbench. My problem is I want to set the inlet temperature as it is at the domains outlet, so it is like a circle. The fluid is being warmed up in that domain. I have read I have to use a DEFINE_PROFILE UDF in that case. But I never used UDFs before and I do not have enough time to search for a good tutorial. Please can someone help me how to set up my analysis to solve my problem. Inlet name: Oil Inlet Outlet name: Oil Outlet Or do you have a link to a turorial or another method how to solve this? Thanks, Romek

 March 7, 2011, 01:42 #2 New Member   Join Date: Mar 2011 Posts: 13 Rep Power: 8 Just figured out I can do it via Expressions. The Statement would be "Tin = areaAve(Oil.T)@Oil Outlet" Can someone confirm this?

 March 7, 2011, 19:54 #3 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,097 Rep Power: 109 Looks OK. Have you considered using a periodic boundary condition?

 March 7, 2011, 20:55 #4 New Member   Join Date: Mar 2011 Posts: 13 Rep Power: 8 whats is the difference of the periodic boundary condition? right now i have a static temperature at the inlet calculated by the expression above.

 March 7, 2011, 22:01 #5 New Member   Join Date: Mar 2011 Posts: 13 Rep Power: 8 i have an other problem. i am simulating the oil flow in an engine. So the pressure level in the galleries ishould be over 3 bar depending on the engine revs. But the pressure level in the oil pan should be atm. When I simulate it as one domain the pressure level in the galleries is ok, but in the oil pan region drops to -0.6 bar rel. pressure. Inlet/Outlet mass flow (which is the same) control the boundary conditions. The domain contains oil and air. What is the best way to set up these conditions? Split it up in 2 domains? Or create an opening for pressure control in the oil pan?

 March 9, 2011, 03:23 plz help #6 New Member   Join Date: Mar 2011 Posts: 6 Rep Power: 8 Hi, I think i have a similar problem to define my boundary conditions i have two narrow long pipes in contreflow configuration so in total i have 4 fluid boundaries to declare in CFX-pre (2 inlets and 2 outlets). well I know the inlet conditions of the first pipe (Temp, pressure and Mass flow rate) Tin1, Pin1, mRin1 As for the second tube inlet conditions i'd like to define them as similar to the first pipe's outlet (Temp, Pressure and mass flow rate) i.e: Tin2=Tout1, Pin2=Tout1, ... How i Can do that I'm quite new user of CFX and i don't know how to define this inlet conditions in CFX-pre. probably with expression right ? can you send me the right tutorial or defintion if possible thank you

 March 9, 2011, 21:10 #7 New Member   Join Date: Mar 2011 Posts: 13 Rep Power: 8 @ afrit: download "Ansys CFX Reference Guide" for that. You will find it in Chapters 14/15. Please can someone help me with my problem?

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