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Old   December 9, 2002, 18:47
Default Free surface
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I am wondering how accurately the commercial cfd codes can simulate the free surface flow around a ship. This problem is generally very difficult especially if you want to compare different hull shapes. Also the methods for free surface calculation are various even for VOF, and I want to know which method and what accuracy(numerical order) are applied. If you know anything about this topic that would be very interesting, maybe about Star-CD, Fluent and Phoenix.

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Old   December 11, 2002, 08:30
Default Re: Free surface
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CFX has undertaken the implementation of a FS model (different from VOF) paid for by the Navy as far as I know.

Since then it has been used for the Americas's Cup by by the NZ defender, Kingfisher, SVA Postdam (Germany) and Qinetiq (UK MOD?) for submarine periscopes (I have seen this in the latest CFX magazine I have received) and this I know only from the CFX magazine. So it seems quite popular and used for ship hull resistance, spray etc... At the last conference I have attended they have presented FSI development work that allows the motion of the hull using the fluid information.

Personally I have only used the code for environmental purposes (river, weir and pump flows with FS). What you track is the fluid (or air) volume fraction (not a scalar) using a homogeneous model (you could also use true multiphase at a higher cost). Once you have started to converge you can switch on mesh adaption to refine the definition of the FS which is usually defined across three elements. You can use first and second order scheme.

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