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

Gravity in vertical pipe

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

Reply
 
LinkBack Thread Tools Display Modes
Old   January 19, 2012, 15:08
Default Gravity in vertical pipe
  #1
jpo
Member
 
Join Date: Apr 2009
Posts: 93
Rep Power: 8
jpo is on a distinguished road
Hello,

does someone know how to run Fluent simulation of a vertical pipe with gravity on?

I don't see any difference in the flow when gravity is enabled...


Many thanks
jpo is offline   Reply With Quote

Old   January 20, 2012, 01:57
Default
  #2
Senior Member
 
Join Date: Mar 2009
Location: Indiana, US
Posts: 185
Rep Power: 8
delaneyluke is on a distinguished road
Could you provide more details, like your BC's and fluid used, single or multi phase.
delaneyluke is offline   Reply With Quote

Old   January 20, 2012, 04:07
Default
  #3
Senior Member
 
Amir's Avatar
 
Amir
Join Date: May 2009
Location: Shiraz, Iran
Posts: 739
Blog Entries: 1
Rep Power: 14
Amir is on a distinguished road
Quote:
Originally Posted by jpo View Post
Hello,

does someone know how to run Fluent simulation of a vertical pipe with gravity on?

I don't see any difference in the flow when gravity is enabled...


Many thanks
Dear friend,

If you don't have pressure BC in incompressible flow fields, including gravity doesn't change the flow field; because you can introduce new pressure variable numerically which includes the gravity term. Obviously, you can find the original pressure field by excluding the added field.

Bests,
__________________
Amir
Amir is offline   Reply With Quote

Old   January 20, 2012, 04:45
Default
  #4
Member
 
Join Date: Nov 2011
Location: Czech Republic
Posts: 95
Rep Power: 5
Sixkillers is on a distinguished road
If you want to see effect of hydrostatic pressure, which depends on gravity, in a pressure field try set the operating density to zero (Cell zone conditions -> Operating conditions -> Specified operating density).
Sixkillers is offline   Reply With Quote

Old   January 20, 2012, 14:42
Default
  #5
jpo
Member
 
Join Date: Apr 2009
Posts: 93
Rep Power: 8
jpo is on a distinguished road
Thank you for the suggestion to set the operating density to zero; it seems to work well now

Thank you for your replies
jpo is offline   Reply With Quote

Old   January 20, 2012, 15:01
Default
  #6
Senior Member
 
Real Name :)
Join Date: Jan 2010
Location: United States
Posts: 180
Rep Power: 7
ComputerGuy is on a distinguished road
(Please delete my message -- wrong post)

Quote:
Originally Posted by jpo View Post
Hello,

does someone know how to run Fluent simulation of a vertical pipe with gravity on?

I don't see any difference in the flow when gravity is enabled...


Many thanks
ComputerGuy is offline   Reply With Quote

Old   January 20, 2012, 15:04
Default
  #7
jpo
Member
 
Join Date: Apr 2009
Posts: 93
Rep Power: 8
jpo is on a distinguished road
It is single phase; just trying to see if the "gravity" option makes a difference in the pressures in a pipe

As a next step I am contemplating to write a UDF to try and modify the gravity vector. Would someone know how to to this?
jpo is offline   Reply With Quote

Old   January 20, 2012, 15:15
Default
  #8
Senior Member
 
Real Name :)
Join Date: Jan 2010
Location: United States
Posts: 180
Rep Power: 7
ComputerGuy is on a distinguished road
Are you talking about modifying the gravity vector as the simulation proceeds, or modification to be something other than -9.81 m/s^2 in the "down" direction? If you're looking at simply modifying it from -9.81, this is what you're specifying in the X, Y, and Z components of gravity when you turn it "on." Instead of -9.81 in the Z direction, if you make it -9.81 in the Y direction, gravity will now be "sideways" instead of "down" as in your previous case.

ComputerGuy

Quote:
Originally Posted by jpo View Post
It is air only; just trying to see if the "gravity" option makes a difference in the pressures in a pipe

As a next step I am contemplating to write a UDF to try and modify the gravity vector. Would someone know how to to this?
ComputerGuy is offline   Reply With Quote

Old   January 20, 2012, 15:19
Default
  #9
jpo
Member
 
Join Date: Apr 2009
Posts: 93
Rep Power: 8
jpo is on a distinguished road
Gravity will be rigidly defined for the entire simulation, but want to make it vary with altitude
jpo 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
energy conservation in vertical pipe Atit Koonsrisuk CFX 1 March 30, 2005 11:41
My Revised "Time Vs Energy" Article For Review Abhi Main CFD Forum 2 July 9, 2002 09:08
Terrible Mistake In Fluid Dynamics History Abhi Main CFD Forum 12 July 8, 2002 09:11
vertical pipe flow sanjib das sharma CFX 2 July 30, 2001 06:17
Effects of gravity in pipe - pressure distribution Anthony Wachs FLUENT 2 July 25, 2001 07:07


All times are GMT -4. The time now is 20:54.