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-   -   Air ventilation around a foil (http://www.cfd-online.com/Forums/numeca/118936-air-ventilation-around-foil.html)

laurent98 June 6, 2013 20:03

Air ventilation around a foil
 
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

lava12005 June 9, 2013 05:27

Do you mean that you don't get the flow like what the video shows? or?

laurent98 June 9, 2013 06:16

1 Attachment(s)
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

Krisayres August 24, 2013 02:15

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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Get more details about this.

laurent98 August 25, 2013 20:43

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

lava12005 August 25, 2013 21:46

Quote:

Originally Posted by laurent98 (Post 447975)
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?

laurent98 September 17, 2013 19:23

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!

laurent98 January 8, 2014 22:46

2 Attachment(s)
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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