# Air ventilation around a foil

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 June 6, 2013, 21:03 Air ventilation around a foil #1 Member   laurentL Join Date: Oct 2011 Location: new caledonia Posts: 73 Rep Power: 14 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

 June 9, 2013, 06:27 #2 Senior Member   KHB Join Date: Aug 2010 Location: Singapore Posts: 118 Rep Power: 15 Do you mean that you don't get the flow like what the video shows? or?

June 9, 2013, 07:16
#3
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laurentL
Join Date: Oct 2011
Location: new caledonia
Posts: 73
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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
Attached Images
 f02_3dview_lowacc.jpg (90.5 KB, 43 views)

 August 24, 2013, 03:15 #4 New Member   kris Ayres Join Date: Aug 2013 Posts: 1 Rep Power: 0 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..?? -------------- Get more details about this.

 August 25, 2013, 21:43 #5 Member   laurentL Join Date: Oct 2011 Location: new caledonia Posts: 73 Rep Power: 14 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

August 25, 2013, 22:46
#6
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KHB
Join Date: Aug 2010
Location: Singapore
Posts: 118
Rep Power: 15
Quote:
 Originally Posted by laurent98 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?

 September 17, 2013, 20:23 #7 Member   laurentL Join Date: Oct 2011 Location: new caledonia Posts: 73 Rep Power: 14 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!

January 8, 2014, 22:46
#8
Member

laurentL
Join Date: Oct 2011
Location: new caledonia
Posts: 73
Rep Power: 14
hi Kris,
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
Attached Images
 2500tstp.jpg (94.6 KB, 19 views) 330tstp.jpg (17.2 KB, 19 views)

 Tags foil, ventilation