CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

Floating body: explosions in the sky

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   October 9, 2013, 05:29
Default Floating body: explosions in the sky
  #1
Senior Member
 
Pablo Higuera
Join Date: Jan 2011
Location: Auckland
Posts: 627
Rep Power: 19
Phicau is on a distinguished road
Hi all,

I am playing around with the floating body capabilities of interDyMFoam. So far I have carried out the floating body tutorial and it runs flawlessly, I then added some waves and eventually it crashed due to the drifting of the body making the mesh horribly distorted, as expected.

I now decided to go for a more complex geometry and created something that represents an offshore platform in a *very* simplified way. The mesh is structured and orthogonal and has hex cells only. Other than that, the BCs, schemes and tolerances are the very same from the floating body tutorial, with updated mass, CoM and inertias.

The case blows up due to non-physical velocities around the edges located in the air area, check the image:




For the record, I know this change is not correct at all but the same case with zeroGradient instead of movingWallVelocity in U BC for the structure is running. Watching the video makes you see that the results are unphysical because water presents a weird behaviour, but it runs...

I have tried other options, none of which works:
- Having additional refinement levels around the structure
- Creating a mesh with cell aspect ratio = 1
- Changing the div(rho*phi,U) scheme to Gauss limitedLinearV 1 and others, known to be more robust
- Selecting very conservative Co numbers or smaller initial deltaT
- Selectively relaxing large air velocities

Any further recommendations?

Thanks!

Pablo
Phicau is offline   Reply With Quote

Old   February 4, 2014, 05:37
Default
  #2
Senior Member
 
Pablo Higuera
Join Date: Jan 2011
Location: Auckland
Posts: 627
Rep Power: 19
Phicau is on a distinguished road
Some news:

I have managed to take care of the well-known pressure fluctuations adapting some techniques from the shipFoam (OF 1.6-ext) solver and others. Finally the case runs, but I feel that OpenFOAM is not the model to simulate floating bodies out of the box at this stage. Anyway, this is not my field and I was just playing...

You can check the results here:

http://www.youtube.com/watch?v=OnjGPbCNF7g

Best,

Pablo
Phicau is offline   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
Floating Body Woody Lee FLOW-3D 1 July 3, 2023 10:50
Waves and a floating body... in CFX? salvooch ANSYS 19 March 25, 2017 15:58
6DOF with floating body bounce back. paka FLUENT 4 June 6, 2013 12:32
Waves and a floating body... in CFX? salvooch CFX 9 January 20, 2011 05:03
Floating body. paka FLUENT 2 June 10, 2010 01:52


All times are GMT -4. The time now is 18:54.