inlet temp = outlet temp

Romek · March 6, 2011, 19:42

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

Romek · March 7, 2011, 00:42

Just figured out I can do it via Expressions.

The Statement would be "Tin = areaAve(Oil.T)@Oil Outlet"

Can someone confirm this?

ghorrocks · March 7, 2011, 18:54

Looks OK. Have you considered using a periodic boundary condition?

Romek · March 7, 2011, 19:55

whats is the difference of the periodic boundary condition?

right now i have a static temperature at the inlet calculated by the expression above.

Romek · March 7, 2011, 21:01

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?

afrit · March 9, 2011, 02:23

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

Romek · March 9, 2011, 20:10

@ afrit: download "Ansys CFX Reference Guide" for that. You will find it in Chapters 14/15.

Please can someone help me with my problem?

March 6, 2011, 19:42	inlet temp = outlet temp	#1
Romek New Member Join Date: Mar 2011 Posts: 13 Rep Power: 15	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 9, 2011, 02:23	plz help	#6
afrit New Member Join Date: Mar 2011 Posts: 6 Rep Power: 15	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

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Mapping outlet patch to inlet patch of new case	val46	OpenFOAM	0	February 18, 2011 11:22
Boundary conditions: inlet and outlet	aline	OpenFOAM	7	June 29, 2010 03:45
ATTENTION! Reliability problems in CFX 5.7	Joseph	CFX	14	April 20, 2010 15:45
Inlet & Outlet Boundaries causing low surface temp	Ted Crilly	Siemens	2	November 19, 2004 08:58
how to set inlet and outlet?	green	Phoenics	5	May 18, 2004 23:52

March 7, 2011, 00:42		#2
Romek New Member Join Date: Mar 2011 Posts: 13 Rep Power: 15	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, 18:54		#3
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,696 Rep Power: 143	Looks OK. Have you considered using a periodic boundary condition?

March 7, 2011, 19:55		#4
Romek New Member Join Date: Mar 2011 Posts: 13 Rep Power: 15	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, 21:01		#5
Romek New Member Join Date: Mar 2011 Posts: 13 Rep Power: 15	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, 20:10		#7
Romek New Member Join Date: Mar 2011 Posts: 13 Rep Power: 15	@ afrit: download "Ansys CFX Reference Guide" for that. You will find it in Chapters 14/15. Please can someone help me with my problem?