CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLUENT

about pressure outlet

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   May 21, 2002, 21:42
Default about pressure outlet
  #1
cwflying
Guest
 
Posts: n/a
In my case,a model is built up with one inlet and two outlets.Before applying pressure outlet conditions at the two outlets. I used "outflow" to carry out some iterations, while the split division ratio (under outlet/up outlet) is resulted from an experience formula, which is to some degree in agreement to the real data in my case. Then I changed it to pressure outlet condition, continuing calculation. Again some iterations, I find the split division ratio is reduced because always there is reversed flow at the under outlet, and the calculation result does not agree well with experiment data. Could anyone give me some advice?
  Reply With Quote

Old   May 22, 2002, 04:19
Default Re: about pressure outlet
  #2
Alammar
Guest
 
Posts: n/a
Is this water? Air? Compressible? How far are the two outlets apart? How far is the inlet?
  Reply With Quote

Old   May 22, 2002, 20:31
Default Re: about pressure outlet
  #3
cwflying
Guest
 
Posts: n/a
water,incompressible. the two outlets are 0.4m apart,inlet and up outlet is about 0.04m apart, distance between under outlet and inlet is over 0.4m. inlet velocity is vertical to the two outlets. Thanks!
  Reply With Quote

Old   May 23, 2002, 06:23
Default Re: about pressure outlet
  #4
Alammar
Guest
 
Posts: n/a
Assuming viscous case, I suspect that reverse flow is near the wall. There is a finite static pressure at the outlet corner, which may be lower than the specified outlet pressure. Make sure your gravity vector is pointed correctly. I suppose your outlet pressure is well known; i.e, 1 atm!
  Reply With Quote

Old   May 23, 2002, 18:52
Default Re: about pressure outlet
  #5
cwflying
Guest
 
Posts: n/a
Yes, I set the operation pressure to be zero, and at the pressure outlet boundary conditions, I let the pressure to be 1 atm at both outlets. And the result static is negative somewhere.
  Reply With Quote

Old   May 24, 2002, 14:36
Default Re: about pressure outlet
  #6
Alammar
Guest
 
Posts: n/a
With regard to the negative pressures, I would make sure I'm using the correct atmosheric pressure for the given input mass flow. I'm sure you know you don't need to run the case again. Simply subtract and add! Assuming you have the right solution!
  Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Problems in pressure when using mass flow rate outlet rafiktharwat CFX 11 January 2, 2014 18:21
pressure oscillation near pressure outlet boundary kino Main CFD Forum 5 April 13, 2011 11:03
Pressure Outlet setting CoG STAR-CCM+ 4 June 9, 2010 21:47
what actually is the 'zero pressure outlet b. c.' hwe001 CFX 4 June 7, 2010 15:22
Backflow occuring at a pressure outlet? Dave FLUENT 1 August 12, 2004 17:39


All times are GMT -4. The time now is 04:30.