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Air ventilation around a foil

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Old   June 6, 2013, 20:03
Default Air ventilation around a foil
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laurentL
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Dear Finemariners,
i'am trying to compute a water flow around a foil with a free surface with ventilation. No success yet. Air should go along the upper face of the foil. A little bit like this video
http://www.youtube.com/watch?v=KRvkRYZhejY
is anyone got advice to help me for setting the case
thanks be advance LL
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Old   June 9, 2013, 05:27
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Do you mean that you don't get the flow like what the video shows? or?
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Old   June 9, 2013, 06:16
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exactly, and i try since 2 weeks a lots of setting combination.big cells, fine mesh, AGR in free surface and pressure Hessian criterion, small time step, steady unsteady etc ...
i attach a picture of the free surface obtained in most of cases
actually i really don t know how to solve this problem...
thank you again for helping
best regards LL
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File Type: jpg f02_3dview_lowacc.jpg (90.5 KB, 36 views)
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Old   August 24, 2013, 02:15
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kris Ayres
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Actually I have tried it using this concept of AGR in free surface and pressure Hessian criterion and I didn't find that much problem. So, can you tell me from the beginning how you have tried it..??
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Old   August 25, 2013, 20:43
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hi Kris,
my main problem is the results validation. in real life with important angles we know that foil ventilate, but finemarine didn't show it... i didn't have experimental results of drag to compare ...
second problem is the representation of the free surface, there is some strange little waves along the foil side...
cheers LL
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Old   August 25, 2013, 21:46
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Quote:
Originally Posted by laurent98 View Post
hi Kris,
my main problem is the results validation. in real life with important angles we know that foil ventilate, but finemarine didn't show it... i didn't have experimental results of drag to compare ...
second problem is the representation of the free surface, there is some strange little waves along the foil side...
cheers LL
Any reference to your problem? what kind of hydrofoil etc?
There is a validation case from the wiki link: Free-Surface Piercing NACA 0024 Hydrofoil.
Does this issue still exist also if you tried to simulate it?
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Old   September 17, 2013, 19:23
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hi lava
sorry i don't have reference for this problem. it s about hydrofoil for little catamaran like F18 or C class.
interesting validation case thanks you, i will tried to simulate it as soon as possible!
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Old   January 8, 2014, 22:46
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hi Kris,
thank you for answered,
i'am back on this issue. i'am no able to predict ventilation yet!
i was not able to get a image of air going along the foil with finemarine like i did with openfoam.
did you?
could you play with sigma and contact angle in finemarine ?
here images of Openfoam Free surface
cheers LL
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File Type: jpg 330tstp.jpg (17.2 KB, 15 views)
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