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Old   August 5, 2008, 07:05
Default planning hulls
  #1
Ciro Cannavacciuolo
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Hi! I'm a cfx user and i'm trying to simulate the flow field around a planning hull. There is a big problem: i note the formation of a air film between the hull and the freesurface. Is there someone that studied this kind of simulation?

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Old   August 7, 2008, 22:44
Default Re: planning hulls
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troy
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we do a lot of planing hull studies and we've seen the same problem. the amount of this "air film" depends entirly on the inflated boundary mesh settings (y+ value), velocity, and immersion. the software developers are well aware of the problem and we're told that they are currently trying to resolve it.
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Old   August 8, 2008, 05:24
Default Re: planning hulls
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Ciro Cannavacciuolo
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ok, thank you!

I noticed that, even if the "air film" is present, the lift calculated is not so different from the experimental data ( about 10% of error ).

Do you have some data about this?

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Old   August 13, 2008, 05:02
Default Re: planning hulls
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Charles
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You get this in other VOF codes too. Try to reduce timestep.
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Old   August 15, 2008, 05:04
Default Re: planning hulls
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cannavacciuolociro ciro
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ok, thank you!

I did simulation with k epsilon turbulent model but i think that k omega is the best.

Don't you think so?

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Old   August 15, 2008, 05:35
Default Re: planning hulls
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Charles
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mmmm. Don't expect it to make too much of a difference for this kind of flow. Anyway, what happens to the turbulence at the air / water interface is another interesting question by itself.

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Old   August 15, 2008, 12:14
Default Re: planning hulls
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cannavacciuolociro ciro
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the k omega model calculate RANS until the wall, without any wall functions. Maybe the problem of the "air film" between the hull and the surface is due to the effect of this wall functions. About the turbolence at the air/water interface i have never studied it. Cuold you tell me something about that? Thank you
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Old   August 9, 2013, 16:12
Default air phase being formed on the bottom of the hull
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Deepak Bansal
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hey buddy i am also facing same problem in planing craft that air phase being formed on the bottom of the hull.................how did u solve this problem.................reply as soon as possible...............
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