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-   -   Problem with VOF and rotating disc in Fluent (http://www.cfd-online.com/Forums/fluent/109462-problem-vof-rotating-disc-fluent.html)

Ludvig November 18, 2012 16:24

Problem with VOF and rotating disc in Fluent
 
Hi all,

I have set up a model with a rotating disc inside a horizontal cylinder that is quarter full of water and the rest is air. I am using the VOF method for multiphase and a rotating wall boundary condition for rotation of the disc.

I patch a region with water and run the solution.

However strange things are happening,

For my steady state solution I have convergence problems and the more iterations i do the less water is left in the cylinder. (seen by volume average) also with increasing number of iterations and once converged, the solution is nonsense (3000 iterations).whereas with only 10-100 iterations the solution seems to be working correctly.

I decided to try and run transient instead and the problem of disappearing water ceases. However now nothing is happening what so ever to the water in the cylinder.

My questions is:

Has someone had some similar experience?

Are there any known problems using VOF with rotating parts?
or with VOF in general that i should be aware of?

Just to clarify:

I am certain the disc is spinning because i can see it on the contour of velocity. I have specified a no slip condition for the wall shears. I have tried disc speeds ranging from 3.14-125rad/s all with similar results for both transient and steady state solutions.

I hope I have mentioned everything of concern if not please ask. (I can also send pictures)
To anyone who has any idea of what could be happening I am very grateful.

Thanks,
Ludvig

bhanu March 13, 2014 20:57

hello Ludvig,
it looks like your model is same like the model i am working on. if you can send me the pictures of your model and how does it look after patch, i might can help you with that. and one more thing does your simulation is time dependent??


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