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Old   January 12, 2009, 01:08
Default Free-surface modeling
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Sam
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Hi,

I am currently undertaking a final year thesis which involves the calculation of the wavemaking ressitance of a submarine.

As a result I have to generate a 3D model with a freesurface.

I have done all the tutes in CFX Pre aswell as the tutorials form ANSYS training manuals however I have not really found any particularly helpful for defining the geometry and meshing this kind of problem.

Does anyone know of any tutorials/literature that will aid me in modeling this problem?

I just want to do something basic at first to get the general idea before prgressing.

I was thinking of creating a large rectangle with a small cylinder inside it mkaing them seperate bodies. Then doing a volume mesh in the rectangle and a surface mesh over the cylinder. Then proceeding to set up the boundary conditions simialr to that in tutorial 7 "Free surface flow over a bump"

Is this a valid approach or is it way off? I know the mesh has to be very fine etc. but I just wanted a very simplistic model to start with.

Regards,

Sam
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Old   January 17, 2009, 17:13
Default Re: Free-surface modeling
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Chebeba
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Someone else might disagree, but AFAIAC you'll never be able to do it using CFX meshing. You have way too little control of the boundary layer, the mesher is too fragile and you can't get a good resolution at the free surface without going to structural meshing.

You'll want to run the ICEM Wing Body Tutorial to get the basic meshing knowledge.

It's in something like C:\Program Files\ANSYS Inc\v110\icemcfd\docu\Tutorials\CFD_Tutorial_Files \WingBody (The files)

And then look in the Tutorial Help for instructions.

Imagine that the symmetry plane is the water surface in this case, and extend your model on the other side too.

/C
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