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

Pressure Outlet

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

Like Tree1Likes
  • 1 Post By CeesH

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 26, 2015, 02:48
Default Pressure Outlet
  #1
New Member
 
Jonathan Koh
Join Date: Nov 2014
Posts: 7
Rep Power: 11
jonathankxx is on a distinguished road
Hi! I have a question on using Pressure outlet as a boundary condition.

My model involves a closed-end room( one end is open, the other is closed). It behaves like a close-end pipe.

My question is, by setting the open end as pressure outlet, would there be any air mass flow in/out through this open end. This is because the room is subjected to temperature changes, and the internal air within the room experiences temperature variances.

And if so, is this condition regarded as a ventilated room?

Thanks!
jonathankxx is offline   Reply With Quote

Old   March 26, 2015, 04:19
Default
  #2
Senior Member
 
Cees Haringa
Join Date: May 2013
Location: Delft
Posts: 607
Rep Power: 0
CeesH is on a distinguished road
Hi Jonathan,

A pressure outlet works both as inlet and outlet - you set the pressure on the outside of the boundary, and based on the pressure difference flow will occur. If the inside pressure is lower, flow will be inward (you will see a "reversed flow in ... faces" notification)

Although I have no experience with modelling free convection in rooms, I'd say it's a suitable boundary condition.

Cheers,
Cees
jonathankxx likes this.
CeesH is offline   Reply With Quote

Old   March 26, 2015, 08:30
Default
  #3
New Member
 
Jonathan Koh
Join Date: Nov 2014
Posts: 7
Rep Power: 11
jonathankxx is on a distinguished road
hi Cees,

oh wow! thanks for the clarification! one more question though. if the inner pressure is higher, this will cause an outflow of air. however, without any inflow of air on the other side, wouldn't the mass equilibrium not being fulfilled?

Thanks,
Jonathan
jonathankxx is offline   Reply With Quote

Old   March 26, 2015, 10:38
Default
  #4
Senior Member
 
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,654
Rep Power: 65
LuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura about
Just wanted to point out, steady flow mass balance applies only to equilibria (i.e. steady state). In transient problems you can have mass flow in an open-ended pipe (like the emptying of a tank). Is your problem stationary or transient?

For steady state case, there would have to be reverse flow to satisfy mass conservation (steady flow mass balance). For transient, there is no such condition (because the flow is not necessarily steady).
LuckyTran is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Issues on the simulation of high-speed compressible flow within turbomachinery dowlee OpenFOAM Running, Solving & CFD 11 August 6, 2021 07:40
static vs. total pressure auf dem feld FLUENT 17 February 26, 2016 14:04
Pressure outlet BC help! eishinsnsayshin FLUENT 7 December 4, 2012 00:36
Unsteady pressure differential between inlet and outlet of the pipe for single phase joshi20h FLUENT 0 September 26, 2012 13:41
Pressure Outlet setting CoG STAR-CCM+ 4 June 9, 2010 22:47


All times are GMT -4. The time now is 05:16.