27th ITTC Reports Available

Discussion in 'Hydrodynamics and Aerodynamics' started by Leo Lazauskas, Sep 3, 2014.

  1. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Reports from the 27th ITTC held last week in Copenhagen have just been made available for download.

    http://ittc.info/downloads/Proceedings/27th Conference/index.pdf

    Scroll down to the last page of the index and click on the reports you want.

    Unfortunately, Firefox doesn't work and Chrome might not.
    I had to use Internet Explorer, like a bloody animal.
     
  2. Ad Hoc
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    Ad Hoc Naval Architect

    Cheers Leo

    The file opens in GC ok, but yup...no 'links' to each report :(
     
  3. Leo Lazauskas
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    Leo Lazauskas Senior Member

    I'll be interested to hear your comments on the reports when you get them.
    I think the content is nowhere near as good as the 26th ITTC which was (apart from some minor cases) exceptionally good.
     
  4. Ad Hoc
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    Ad Hoc Naval Architect

    I can down load using IE on my laptop...but not not CG on either my desktop or laptop?
    When I get a few mins..i'll have a read. Bit snowed under right now!
     
  5. Leo Lazauskas
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    Leo Lazauskas Senior Member

    You might have IE somewhere on the desktop machine. You, like everyone else, probably used it to download CG or Firefox immediately after getting the machine :)
     
  6. Ad Hoc
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    Ad Hoc Naval Architect

    Had a read of the Resistance Committee Report, was a bit fluffy and non-committal and didn't really say much or anything of importance at all, sadly.

    They have really missed out in putting to bed once and for all on the world wide resistance reviews and blind tests spectacularly. What a major failure. Such a simple task, yet not able to implement it. The reasons they cite are somewhat lame.

    4/10
     
  7. Remmlinger
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    Remmlinger engineer

    Added resistance in waves

    I thought the diagrams on page 6 of the Resistance Committee Report looked interesting. I was curious because the influence of bow flare on added resistance is still under discussion in yacht design. The analysis was made numerically with OpenFoam. Hull no.5 does not follow the trend, looks like an outlier. The original paper gives no explanation for the deviation of hull no.5. It turns out, that the CFD analysis was conducted for a fixed Wigley hull at FN=0.2 without heaving and pitching and the added resistance was only 0.5% of the total resistance. The CFD-calm-water-resistance for the Wigley hull was not validated against tank data and the absolute numerical value of the resistance is not disclosed. The paper suffers from this epidemic plague that results are always divided by a "reference value".
    All in all a big disappointment and the citation in the Resistance Report is misleading.
    Uli
     
  8. Ad Hoc
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    Ad Hoc Naval Architect

    Uli

    There is a good reference paper "The effect of forebody section shape on ship behaviour in waves" by Moor, Parker & Pattiulo in RINA Transactions 1961. No ambiguity there...might be worth a read; despite it being on large vessels.
     
  9. Remmlinger
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    Remmlinger engineer

    Thanks a lot, I ordered the paper and from a first glance the results seem to be helpful indeed. The names of the authors are Swaan and Vossers from Wageningen. I just learned that modern CFD-results can not compete with tank tests that were conducted more than 50 years ago.
     
  10. jehardiman
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    jehardiman Senior Member

    I think it's more use the data that's available...one of the things I look for in papers is answer = (complicated equiation)*(imperical factor from data). Do that well and you can make Wigley hull data fit any hull form. I was once told in a meeting that one hull of two different hull forms was better than another because its Admiralty Coefficient was lower :rolleyes:
     
  11. Ad Hoc
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    Ad Hoc Naval Architect

    Doh!....should have said; I could have brushed off the dust and scanned it in for you. Its on my bookshelf behind me right now!

    :p:D:p
     
  12. cmckesson
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    cmckesson Naval Architect

    Exactly why I prefer to use Answer = simple formula extracted from data, with warning that it is only accurate to +/- x %.

    I find that we get bogged down calculating answers to six significant figures, while ignoring the fact that the entire calculation is based on a simplification to begin with.
     
  13. Leo Lazauskas
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    Leo Lazauskas Senior Member

    As any fule kno, the von Kármán constant (kappa) plays an important
    role in the analysis of wall-bounded turbulent flows. The current best
    estimate (kappa=0.39) is claimed to be within about +/-10%, based on high
    quality lab experiments a bit above Rn = 10^7.

    In recent work, it was estimated that to get to within +/-1% would
    require experiments at Rn = 10^300.

    Sometimes you just have to accept rough approximations :)
     
  14. tspeer
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    tspeer Senior Member

    I can't get the links to work in IE, Chrome or Firefox. Can someone post the links in html?
     

  15. Leo Lazauskas
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    Leo Lazauskas Senior Member

    http://www.ittc2014.dk/
     
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