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

On the alpha Eqn of VOF method when using Immersed boundary method in OpenFOAM

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 1, 2013, 21:03
Default Alpha Eqn of VOF method when using Immersed boundary method in OpenFOAM
  #1
Member
 
David Long
Join Date: May 2012
Location: Germany
Posts: 64
Rep Power: 6
keepfit is on a distinguished road
Hi,

I am interested in the implementation of Immersed Boundary (IB) / fictitious-domain method in OpenFOAM, and also read some related papers/pretensions like:

1. Zeljko Tukovic, Hrvoje Jasak (2012). Immersed boundary method in OpenFOAM (7th OF workshop)

2. Oscar M. Curet, et al (2010). A versatile implicit iterative approach for fully resolved simulation of self-propulsion. Computer Methods in Applied Mechanics and Engineering


I thought it might not be so difficult to extend the use of IB method with volume of fluid (VOF) method, e.g an enhanced version of interFoamsolver which supports immersed rigid body in the fluid domain.

Look to the original alpha Eqn of VOF method in OF:



in IB method the solid phase is considered as "fluid" but with some constraint conditions to enforce the "fluid" moving as a rigid body. I wouldn't repeat the momentum and constraint equations here (one can see in the 2. paper) here.

However, there are some problems I am facing:

1. If the immersed solid body is moving in the fluid domain and has different density (e.g. rocks or steel), how do we account for the changes to the P Eqn while momentum Eqn remains the same?

2. Most importantly, if there are two fluid phases (e.g air and water) and we introduce VOF method along with IB method, how do we change the alpha Eqn so that we can capture the interface between air and water, as well as the interface between fluid and immersed solid body? Because within the solid body, both alpha1 and alpha2 (alpha2 = 1 - alpha1) should be set as Zero, if we see the solid phase is alpha3, and set its value alpha3 = 1 within the solid body and alpha3 = 1 outside, how can we modify the alpha Eqn account for the 3rd phase alpha3?

Any hints (especially related papers on VOF + IB in CFD) or recommendation will be highly appreciated.

Thanks for your attention.

Cheers,

David

Last edited by keepfit; October 4, 2013 at 22:55.
keepfit is offline   Reply With Quote

Old   January 29, 2014, 16:57
Default
  #2
New Member
 
Andrew Ho
Join Date: Jan 2014
Posts: 6
Rep Power: 4
everyday is on a distinguished road
Hi David,
Have you made any progress on this front? I'm also interested in creating a two phase VOF, moving immersed boundary simulation.
everyday is offline   Reply With Quote

Old   January 30, 2014, 05:59
Default General moving objects
  #3
Senior Member
 
Fabian Roesler
Join Date: Mar 2009
Location: Germany
Posts: 209
Rep Power: 10
fabian_roesler is on a distinguished road
Hi

for the third phase you have to add another phase fraction alpha3 so alpha, the sum of all phase fractions is still one. This is done in multiphaseInterFoam.
I once read some articles about immersed rigid body in fluid domains. Flow 3D has a certain technique called FAVOR to simulate general moving objects. They have some articles about their method published free. Maybe these articles can clarify some of your questions. I do not have access to my literature database so I can not give you any more details. Have a look to these links:

http://www.flow3d.com/pdfs/tp/genera...-flow-9-05.pdf

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.186.5829&rep=rep1&type=pdf

Cheers

Fabian
fabian_roesler is offline   Reply With Quote

Old   January 30, 2014, 06:41
Default
  #4
Senior Member
 
Pablo Higuera
Join Date: Jan 2011
Location: Singapore
Posts: 306
Rep Power: 8
Phicau is on a distinguished road
There is a very interesting and slightly more recent thread on the Fictitious Domain method:

Is Immersed Boundary Method already available in OF 2.1.x or 2.2.x
Phicau is offline   Reply With Quote

Old   January 31, 2014, 15:32
Default
  #5
New Member
 
Andrew Ho
Join Date: Jan 2014
Posts: 6
Rep Power: 4
everyday is on a distinguished road
Thanks guys for the responses, I will have a closer look at this fictitious domain method, since it might do the job. Fabian, I'll have a look at those papers as well.

cheers!
everyday is offline   Reply With Quote

Reply

Tags
ib method

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
Question about heat transfer coefficient setting for CFX Anna Tian CFX 1 June 16, 2013 06:28
Immersed boundary method, again... kekko OpenFOAM 4 February 22, 2011 12:39
Code for Immersed Boundary Method (ask for help) syq129 Main CFD Forum 2 November 23, 2010 04:16
[Other] Ansys Immersed Boundary Method Virtual-iCFD ANSYS Meshing & Geometry 1 July 15, 2010 20:46
immersed boundary method with unstructured mesh x.zhang Main CFD Forum 0 August 25, 2002 21:57


All times are GMT -4. The time now is 01:12.