Water droplet, VOF

mirabella · September 15, 2011, 15:09

Hello everybody,

i'm pretty new with Fluent and Multiphase flows. i aim to simulate the interaction between droplet and wall film in a bearing chamber of gas turbine.
i have some problems by defining sharp interfaces for the liquid film and the droplet. i used the sequence Mark/adapt until the message "0 cells for refinement.." appears, but the interface seems to be staggered.
have anyone idea what to do there?

i've another problem by seperating cells into two zones. I get the error message :"Hanging node.."
It would be very kind, when you share here your experience.

regards,
Mira

lapin_tout_fou · September 16, 2011, 11:42

Hi,

For someone who is new in FLUENT, your problem seems really difficult.
Especially the wall film which is not yet possible in FLUENT.
I know developpers are working on it ant that it will probably commercialized in the next version of the software, but today it seems hard to achieve what you're planning, except of course if you realized your own UDF.
For your problem you should contact the support.

m2montazari · September 18, 2011, 15:33

hi,
I think you can solve this problem but it is somewhat hard! in VOF the interface is sharpest among other models available in fluent. it is said that 3-cell interface is a good interface capturing in VOF. my suggestions are: create a grid that has a very high resolution near the film and the about the locations of the interaction. prefer quadrilateral cells. then reduce timestep to very small size(about 1e-5 sec) and choose a good discritization for parameters(it is probably the hardest step!) and iterate. as the multiphase flows are very sensitive timestep in fluent, I put an emphasise to the timestep size.
I dont know it help or not, but I hope...
yours,
mohammad

September 15, 2011, 15:09	Water droplet, VOF	#1
mirabella New Member mira Join Date: Jun 2011 Posts: 6 Rep Power: 14	Hello everybody, i'm pretty new with Fluent and Multiphase flows. i aim to simulate the interaction between droplet and wall film in a bearing chamber of gas turbine. i have some problems by defining sharp interfaces for the liquid film and the droplet. i used the sequence Mark/adapt until the message "0 cells for refinement.." appears, but the interface seems to be staggered. have anyone idea what to do there? i've another problem by seperating cells into two zones. I get the error message :"Hanging node.." It would be very kind, when you share here your experience. regards, Mira

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September 16, 2011, 11:42		#2
lapin_tout_fou New Member Thomas Join Date: Aug 2009 Location: France Posts: 12 Rep Power: 16	Hi, For someone who is new in FLUENT, your problem seems really difficult. Especially the wall film which is not yet possible in FLUENT. I know developpers are working on it ant that it will probably commercialized in the next version of the software, but today it seems hard to achieve what you're planning, except of course if you realized your own UDF. For your problem you should contact the support.

September 18, 2011, 15:33		#3
m2montazari Senior Member Mohammad Join Date: Feb 2010 Location: Shiraz, Iran Posts: 108 Rep Power: 16	hi, I think you can solve this problem but it is somewhat hard! in VOF the interface is sharpest among other models available in fluent. it is said that 3-cell interface is a good interface capturing in VOF. my suggestions are: create a grid that has a very high resolution near the film and the about the locations of the interaction. prefer quadrilateral cells. then reduce timestep to very small size(about 1e-5 sec) and choose a good discritization for parameters(it is probably the hardest step!) and iterate. as the multiphase flows are very sensitive timestep in fluent, I put an emphasise to the timestep size. I dont know it help or not, but I hope... yours, mohammad