CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > CFX

Modelling Air Bubbles

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

LinkBack Thread Tools Search this Thread Display Modes
Old   May 25, 2017, 08:58
Question Modelling Air Bubbles
New Member
Join Date: May 2017
Posts: 1
Rep Power: 0
fluidflow5 is on a distinguished road

I am looking to model air bubbles rising in water. Particularly, I would like to see the coalescence and break up of the bubbles. My simulation has gas entering at a speed of 0.001 m/s at the bottom of a water column. The issue I am having is that one bubble forms initially, and then following it is simply a stream of air.

I am running a transient scheme with a timestep of 0.001 [s]. Air is set to a dispersed fluid with water as a continuous fluid. I have turned on the free surface model with an interface compression level of 2. My turbulence is homogeneous and modelled by k-Epsilon.

For the fluid pair, I have set a surface tension coefficient of 0.072 N/m and a continuum surface force with water as the primary fluid. Interphase transfer is set to Particle Model. I have also chosen appropriate drag and non-drag forces for the model.

From my settings, can anyone spot a reason as to why this may be occurring? Any help is appreciated!
fluidflow5 is offline   Reply With Quote

Old   May 25, 2017, 20:48
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,732
Rep Power: 143
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
You appear to be modelling this using the free surface model? This is the most expensive type of multiphase model, but does allow you to model the detailed dynamics of the interface. Is this what you intend? Or can you do this with a simpler Eularian model?

There are zillions of studies of bubbles rising in water in the literature. I recommend you read a range of them to find out what approaches they have used.

Before the simulation you need to ensure that the configuration you intend to model is correct where you expect bubbles to form and not a jet. Also determine whether you expect to be in the spherical, spherical cap, or other bubble regimes as well.

After you have done this background work you are ready to start simulating. I will get onto that in a future post.
ghorrocks is offline   Reply With Quote


air bubble, bubble, bubble column, water and air

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
Modelling room ventilation air flow todda7 Main CFD Forum 0 April 12, 2017 14:51
[DesignModeler] Environmental Air Modelling oozcan ANSYS Meshing & Geometry 2 August 14, 2016 18:52
Radiation interface hinca CFX 15 January 26, 2014 17:11
How simulate air bubbles into water turbine? farzola Main CFD Forum 0 April 8, 2010 09:35
Modelling BC for Air intake snorkel of automobile Piyush FLUENT 1 May 18, 2006 05:36

All times are GMT -4. The time now is 13:02.