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[waves2Foam] Calculating only the buoyancy force of a floating object moving in waves

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Old   February 5, 2016, 01:34
Default Calculating only the buoyancy force of a floating object moving in waves
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Hi Everyone,

Apologies in advance if my question may sound very simple but I cannot figure out the best way to do this. I am interested in calculating only the buoyancy force of a floating object moving in waves. I would like to emphasise I need to seperate the buoyancy from the total force (wave force+buoyancy force). I thought of two ways but none gives exactly what I want:

1) calculate it from the integral of volume fraction over the surface of the body. However, this would only give me the surface area of submerged body. For cylindrical geometries I can convert that into volume and force but not for bodies with complex geometries.

2) integrating the rho*g*h*alpha over the body. If I define gh as
Code:
volScalarField gh("gh", g & mesh.C());
then "h" is not measured from the instantaneous free-surface location and is only the coordinates of centre of the mesh.

I would highly appreciate any comments/ideas.

Many thanks in advance
Ashkan
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Old   February 14, 2016, 18:26
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Stefan
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@ashkan
Your first approach should be the right one. From divergence theorem you may argue that the ratio of the wetted surface area to the total surface area of your floating body equals displacement,
see i.e. equation 3-4 on page 12 here:
http://web.mit.edu/flowlab/pdf/Nonli...ve_Impulse.pdf
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Old   February 15, 2016, 04:37
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Quote:
Originally Posted by SD@TUB View Post
@ashkan
Your first approach should be the right one. From divergence theorem you may argue that the ratio of the wetted surface area to the total surface area of your floating body equals displacement,
see i.e. equation 3-4 on page 12 here:
http://web.mit.edu/flowlab/pdf/Nonli...ve_Impulse.pdf
Many thanks Stefan. I really appreciate your comments and the paper.
Kind regards
Ashkan
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