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

Twin-fluid mixing

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   April 16, 2002, 04:08
Default Twin-fluid mixing
  #1
Thomas
Guest
 
Posts: n/a
Hi I am mixing water and air in a mixing chamber. The angle between the inlets to the chamber is 52 degrees. The water is flowing with 7 m/s and the air with 140 m/s. I am using the k-e model in a transient simulation. When using the homogeneous approximation, I get much too high velocities and pressure.

Does anyone have experience with this kind of problem in CFX4?

Kind regards Thomas
  Reply With Quote

Old   April 16, 2002, 20:42
Default Re: Twin-fluid mixing
  #2
Mike
Guest
 
Posts: n/a
I'm not sure if the homogeneous model would be valid. I don't have any experience with CFX-4, but if the homogeneous model is solving for a single velocity field (check in the documentation) then it's not valid for a dispersed air phase in water (i.e. air bubbles in water). A multiphase model that solves for a single velocity field would be used, for example, in free surface flow where both fluids are continuous. A Particle model would be more appropriate for multiphase mixing applications.
  Reply With Quote

Old   April 17, 2002, 03:54
Default Re: Twin-fluid mixing
  #3
Thomas
Guest
 
Posts: n/a
The flow in the domain is with a film of water at the side walls and only a few drops in the centre, where the air is flowing. Therefore I figured that the homogeneous model, which only solves for one solution field, would be appropriate (2 continuous phases).

Is it possible that a solution is easier reached when using a mixture in the two inlets (99 vol% air and 1 vol% water in one inlet and vice versa in the other inlet) rather than using pure air and water ?
  Reply With Quote

Old   April 17, 2002, 20:34
Default Re: Twin-fluid mixing
  #4
Mike
Guest
 
Posts: n/a
I wouldn't have thought that would help since 1% water would be a dispersed phase. Not sure what else to suggest without seeing the geometry. How does the water form a thin film at the walls - is the domain spinning? I'm guessing you'd need a fine mesh to resolve the film - say at least 10 nodes across the thickness of the film.
  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
How to setup two mixing fluid (no reaction) Miner FLUENT 3 April 10, 2016 14:32
Fluid pairs fjalil Main CFD Forum 0 June 10, 2009 14:47
What is the total energy for incompressible fluid? Harry Dong Main CFD Forum 12 February 4, 2006 01:55
My Revised "Time Vs Energy" Article For Review Abhi Main CFD Forum 2 July 9, 2002 10:08
Terrible Mistake In Fluid Dynamics History Abhi Main CFD Forum 12 July 8, 2002 10:11


All times are GMT -4. The time now is 04:25.