# Will it float?

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 October 5, 2006, 12:52 Will it float? #1 Dave Letterman Guest   Posts: n/a Hello, We have seen some free surface flows and DOF animations from cd-adapco. But how do they know the final mass of the floating object (boat, platform, slohing tank). The mass certainly has an infulence on the free surface response(?). Can you calculate the mass and center of gravity from the CAD data? Do we have to perform various runs assuming various mass/load as a parameter? In this case How do you do find the starting flotation line? Some may say vof simulation are useless for engineering purposes if the assumed mass and center of gravity do not correspond to the actual ones of the boat or floating object. Does that make sense to you? Any suggestion? Thank you, Dave

 October 6, 2006, 15:20 Re: Will it float? #2 Paul Schaefer Guest   Posts: n/a Dave, I see why you have trouble beating me at this game. I would argue the CFD VOF approach doesn't need to know the mass of the floating object. As far as the VOF calculations are concerned the object's mass is irrelevant. It is the shape of the displaced fluid volume which matters. However if you want to do a time marching coupled fluid structure problem & compute the structure's motion, that's another matter. Yes you can get CG & mass from CAD data - assuming the geometry & density distribution are accurate. I would compute my starting flotation line using my CAD package. Use the hull shape to generate the displaced volume. Then compute the CG & mass of the displaced volume. Update the displaced volume's position until you get static equilibrium. Then I use the VOF results to get the dynamic part. People say a lot of things that are wrong. "The purpose of computing is insight, not numbers." - Hamming - 1973. Paul

 October 8, 2006, 12:25 Re: Will it float? #3 Alan Carter Guest   Posts: n/a Well pointed out : Hamming was obviously a weak one. May be he was the kind of guy unable to ever get acurate enough numerical results but proficient do a lot of blahblah instead. Is he cooking beeeaaans? Is zorro on? Alan

 October 12, 2006, 15:43 Re: Will it float? #4 Larry David Guest   Posts: n/a It sounds like cd-adapco "greatests moment in presidential speeches". However you have forgotten "WHAT TAAAAAAIME IS IT?" And don't forget to curb your enthousiasm with the star-cad series. Larry

 December 8, 2006, 23:38 Re: Will it float? #5 Patrick Bailcaro Guest   Posts: n/a Much more to the point: When is Dave going to resume "Will It Float?" They haven't done it in WEEKS! "Fun Facts" are good; "Know Your Current Events" is a colossal waste of time. Bring back Will It Float!"

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