Validating CFD results

Discussion in 'Sailboats' started by m_liddell, Feb 1, 2005.

  1. m_liddell
    Joined: Feb 2005
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    Location: Southampton UK

    m_liddell Junior Member

    I'm at Southampton university in the UK currently doing CFD analysis on the 29er main and mast while sailing upwind. The streamline images and vector plots look very close to wind tunnel images with the k-omega SST turbulance model, but I need a better way to validate the results. Is there any performance data for high performance sailing dinghy sails availible or on the net?

    Any help would really be appreciated.
    --
    Mark
     
  2. MikeJohns
    Joined: Aug 2004
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    Location: Australia

    MikeJohns Senior Member

    There was some data published from the Australian Maritime college I can't find the paper I had but they would be worth a try when the academic year resumes. Some of your staff at Southampton will have contacts there.

    Good luck
     
  3. nico
    Joined: Jan 2003
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    nico Senior Member

    What about the comparaison of lift drag for CFD and Wind tunnel? Are they similar?
     
  4. m_liddell
    Joined: Feb 2005
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    Location: Southampton UK

    m_liddell Junior Member

    I have a really limited time frame and resources for this project so unfortunately I can’t do any wind tunnel work. If there is any published data on wind tunnel tests for high performance dinghy sails that would be useful too.

    A friend of mine has a contact with North sails in the US so I might try them, although I suspect they will be reluctant to divulge any of their data.

    MikeJohns: I’ll get in contact with AMC as soon as their academic years starts, thanks for the info.
     

  5. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    I've not seen any published data on sails of the quality you'd need to validate a NS CFD model.

    You might try validating against the key flow features you'd find on a sail. Especially important would be separation bubbles of all kinds, both laminar bubbles leading to transition and the large regions of turbulent separation behind the mast and reattachment farther back on the sail. There are academic problems of this kind, like the classic backward facing step.

    Another big factor is a sail is inherently an aeroelastic problem, so just knowing what the actual sail shape is in a real test is a problem.

    You might contact Mikko Brummer @ WB Sails (Mikko@wb-sails.fi). They've done vortex-lattice CFD and run some wind tunnel tests. A small firm like that may be more interested in a cooperative R&D effort.
     
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