Buoyancy?

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 March 2, 2007, 09:14 Buoyancy? #1 jon Guest   Posts: n/a Hi all, I want to model a boat with mesh deformation and buoyancy. Obvously a boats buoyancy depends on the amount of water it displaces. so to determin where a boat lies in the water I need to calculate the amount of water it is displacing. Anyone know of a way this could be calculated in CFX? Thanks

 March 2, 2007, 09:47 Re: Buoyancy? #2 Patrick Guest   Posts: n/a I don't think that CFD is the right technology to determine that. If you know the weight of your ship you can determine the water displacement with your CAD. If you want to calculate the waves too you come closer to CFX. Regards Patrick

 March 2, 2007, 09:56 Re: Buoyancy? #3 Johnny Guest   Posts: n/a In CFX you would need to use CCL expressions or user Fortran to calculate the z height of the boat. The forces on the hull in the z direction should equal the mass of the boat * gravity.

 March 2, 2007, 10:02 Re: Buoyancy? #4 jon Guest   Posts: n/a The end goal is to try and model planing vessels. Obviously advanced I know but that is the goal. So I have to use CFX to calculate displacement.

 March 2, 2007, 12:08 Re: Buoyancy? #5 opaque Guest   Posts: n/a Dear jon, Can ANSYS CFX do that? Yes it can, and there are a few CFX users already modeling boats floating near piers, interaction of waves between two boats, etc.. You must use a homogeneous multiphase flow model (in 11.0 the coupled volume fraction approach will work wonders on this type of flow), with moving mesh (the hull of your boat is a moving boundary) and you must write your own dynamics for the boat.. The tutorial for moving mesh explains how to simple cases by using CEL expressions, but for more complex dynamics you may need a 6 degrees of freedom solution algorithm as well. You should contact your CFX representative and ask directly how the can help you start your simulation, and/or if they have any information that they could share with you. There may be skeleton User Fortran for the boundary motion, etc.. Opaque.

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