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

Inlet, no Outlet

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

Like Tree1Likes
  • 1 Post By ghorrocks

Reply
 
LinkBack Thread Tools Display Modes
Old   March 30, 2012, 14:35
Default Inlet, no Outlet
  #1
Member
 
Join Date: Jan 2012
Location: Indiana, USA
Posts: 84
Rep Power: 5
Torque_Converter is on a distinguished road
Send a message via AIM to Torque_Converter
Hello All,

I am looking to see the time it takes, and the pressure created when a flow of oil is introduced to a previously air filled chamber. I am well versed in inlet/outlet flow and rotational closed domain flow, but this one stumps me.

Thanks
Torque_Converter is offline   Reply With Quote

Old   March 31, 2012, 07:17
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,646
Rep Power: 84
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Can you describe it a bit more completely? Do you have a chamber filled with air at time zero, and then you add some oil to it (how? under pressure or a defined flow rate?) and the pressure in the air chamber increases? Does the chamber have any inlets or outlets? Is it steady state or transient?
Torque_Converter likes this.
ghorrocks is offline   Reply With Quote

Old   March 31, 2012, 09:28
Default
  #3
Member
 
Join Date: Jan 2012
Location: Indiana, USA
Posts: 84
Rep Power: 5
Torque_Converter is on a distinguished road
Send a message via AIM to Torque_Converter
Yes, a chamber is filled with air at t=0s. This chamber has no outlet, only an inlet. At t=0s oil is introduced through this inlet at P=2 atm (just random numbers), consistently applied. The air would be displaced, and some diffusion into the oil but i'm not worried about that so much. I suppose it could be modeled as an empty chamber at t=0s and then oil added and it would still be accurate.
While the boundary conditions are steady state, I would say the problem is a transient one. The goal of the analysis is to determine how long this is taking since the fluid is VERY viscous and the inlet is rather small.
Torque_Converter is offline   Reply With Quote

Old   March 31, 2012, 16:18
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,646
Rep Power: 84
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
This sounds like something which can be worked out with elementary thermodynamics as a pen and paper calculation, not needing CFD at all. Why are you thinking of doing it using CFD?
ghorrocks is offline   Reply With Quote

Old   March 31, 2012, 16:28
Default
  #5
Member
 
Join Date: Jan 2012
Location: Indiana, USA
Posts: 84
Rep Power: 5
Torque_Converter is on a distinguished road
Send a message via AIM to Torque_Converter
I would agree to be honest, pressure drop, mass flow rate, etc. all easy enough to look into. But I am often asked to do things which produce "pretty pictures". Honestly, I may do the hand calculations and then force a simulation to match. But ultimately, yes, knowing the entry conditions, fluid properties, etc. it is an extremely elementary problem.
Torque_Converter is offline   Reply With Quote

Old   April 1, 2012, 06:48
Default
  #6
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,646
Rep Power: 84
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
The simulation you describe appears to be a straight forward transient compressible gas/oil free surface simulation. But to get a mesh fine enough to look "pretty" will require a fine mesh, and that means a long run time. So this model is going to take a while to develop and a while to run. If all you want is pretty pictures then I recommend photoshop
ghorrocks is offline   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
Help ASAP! pressure inlet & outlet engahmed FLUENT 0 June 13, 2010 15:33
Inlet but not outlet mireis FLUENT 1 June 10, 2010 10:56
ATTENTION! Reliability problems in CFX 5.7 Joseph CFX 14 April 20, 2010 15:45
Duct Flow with 90 degree inlet and outlet k FLUENT 3 August 19, 2007 14:30
inlet and outlet boundary condition of pump Thammasak CFX 0 February 9, 2004 14:02


All times are GMT -4. The time now is 16:37.