# Why is the pressure larger than the total pressure

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 November 9, 2012, 04:41 Why is the pressure larger than the total pressure #1 New Member   Join Date: Apr 2011 Posts: 8 Rep Power: 8 I am simulating a gas flow through a rotating multi-channels with CFX, both the inlet and outlet are the Opening boundary condition. While the inlet has a reletive pressure of 4atm, and the outlet of 2atm, rotation speed is 10000r/min. When I look the result of my computation, at the inlet plane, the pressure is larger than the total pressure, how could this happened?

 November 9, 2012, 05:30 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,319 Rep Power: 110 Can you show some images of what you are seeing?

 November 9, 2012, 06:07 #3 New Member   Join Date: Apr 2011 Posts: 8 Rep Power: 8 [IMG] These are the inlets, the range of the contour is local, from the picture we can see that the pressure is larger than the total pressure in the inlets plane, I don't know why. Last edited by greatwall; November 9, 2012 at 06:12. Reason: the pictures didnot show well

 November 9, 2012, 06:09 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,319 Rep Power: 110 Sorry, I do not download files from other websites. Please post them as attachments to this post (using "Go Advanced").

 November 9, 2012, 06:12 #5 New Member   Join Date: Apr 2011 Posts: 8 Rep Power: 8 [IMG]http://b323.photo.store.qq.com/psb?/V13rxVKa3rhjqK/dwmy9NgB8guQ2FZrPtVmGUFOOzoOhbMyE*ps3QsggBA!/b/dGl*isCnAAAA&bo=hAOAAQAAAAADACM![/IMG]

 November 9, 2012, 06:24 #6 New Member   Join Date: Apr 2011 Posts: 8 Rep Power: 8

 November 9, 2012, 06:36 #7 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,319 Rep Power: 110 We will need to see a bit more of the geometry to make any sense of it. Can you post an image which shows what the flow is actually doing? Also, is this boundary on a rotating frame of reference? Multiphase? Does it have reverse flow?

 November 9, 2012, 06:51 #8 New Member   Join Date: Apr 2011 Posts: 8 Rep Power: 8 This boundary is on a rotating frame of reference, no multiphase. The geometry is a turbine blade internal cooling channel, in the computation, the trailing edges did have reverse flow. 3.jpg

 November 9, 2012, 16:22 #9 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,319 Rep Power: 110 Where is the axis of rotation for the domain?

 November 9, 2012, 21:36 #10 New Member   Join Date: Apr 2011 Posts: 8 Rep Power: 8 The axis of the rotation is on the negative y direction

 November 11, 2012, 06:10 #11 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 14,319 Rep Power: 110 I see. I cannot explain what you are seeing. What does the total pressure in the stationary frame of reference look like?

 November 12, 2012, 21:49 #12 New Member   Join Date: Apr 2011 Posts: 8 Rep Power: 8 The problem has been solved. Thank you! When I put the total pressure in the stationary frame of reference, the result is correct.

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