# Multiphase analysis

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 April 11, 2010, 09:42 Multiphase analysis #1 New Member   Join Date: Apr 2010 Posts: 6 Rep Power: 9 Sponsored Links I am trying to learn the CFX capability for performing multiphase (air + water) analysis. When I get results, I get two heat transfer coefficients viz "Air. Heat Transfer Coefficient" and "Water. Heat Transfer Coefficient". How do I interpret the results to find the effective heat transfer coefficient?

 April 11, 2010, 20:23 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,735 Rep Power: 106 This is all discussed in the documentation, see under solver modelling/multiphase/boundary conditions/wall boundaries

 April 12, 2010, 11:59 #3 New Member   Join Date: Apr 2010 Posts: 6 Rep Power: 9 Dear Mr. Horrocks, Thanks a lot. I could get the documentation. When I run some of the cases (flow inside the pipe) I get the following message. Can you indicate the type and extent of inaccuracy in analysis due to the same? ****** Notice ****** A wall has been placed at portion(s) of an OUTLET boundary condition (at 1.4% of the faces, 2.4% of the area) to prevent fluid from flowing into the domain. The boundary condition name is: Outlet. The fluid name is: Air at 25 C. If this situation persists, consider switching to an Opening type boundary condition instead. With best regards, Dev325

 April 12, 2010, 18:27 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 13,735 Rep Power: 106 This question has been asked thousands of times. Do a search on the forum for comments on this issue.

 April 13, 2010, 19:33 #5 Member   Ali Torbaty Join Date: Jul 2009 Location: Sydney, Australia Posts: 72 Rep Power: 10 Change your Outlet BC into an Open BC and use hydrostatic pressure through CEL.

 April 13, 2010, 22:17 #6 New Member   Join Date: Apr 2010 Posts: 6 Rep Power: 9 I would go through the posts more carefully and thoroughly. Thanks.

April 14, 2010, 06:09
#7
Super Moderator

Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 13,735
Rep Power: 106
Quote:
 Change your Outlet BC into an Open BC and use hydrostatic pressure through CEL.
This is one approach and there are many others. Sometimes this approach is not a good choice - but again this issue has been discussed thousands of times so search the forum for a complete discussion.

 Tags multi phase, water and air

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