The University of Oxford Has Created Conditions That Generate Freak Waves

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Fascinating stuff and maybe a hint for Ocean Sailors on when conditions could increase the probability of freak waves.

http://www.ox.ac.uk/news/2019-01-23-famous-freak-wave-recreated-lab-mirrors-hokusai’s-‘great-wave’

The researchers found it was only possible to reproduce the freak wave when the crossing angle between the two groups was approximately 120 degrees.

When waves are not crossing, wave breaking limits the height that a wave can achieve. However, when waves cross at large angles, wave breaking behaviour changes and no longer limits the height a wave can achieve in the same manner.........

........ Experiments were carried out in the FloWave Ocean Energy Research facility at the University Of Edinburgh.

Dr Sam Draycott at the University of Edinburgh said: ‘The FloWave Ocean Energy Research Facility is a circular combined wave-current basin with wavemakers fitted around the entire circumference. This unique capability enables waves to be generated from any direction, which has allowed us to experimentally recreate the complex directional wave conditions we believe to be associated with the Draupner wave event.’
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[video=youtube;QWWe9PMuVng]https://www.youtube.com/watch?time_continue=11&v=QWWe9PMuVng[/video]
 
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awol said:
Apart from the thread title what has Oxford got to do with it? Spokesman and tank are at UoE.
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Full paper is at https://www.cambridge.org/core/serv...and_the_role_of_breaking_in_crossing_seas.pdf , which lists Dr McAllister as a member of the Engineering Science dept at Oxford; in 2017, he published a paper on a similar topic, https://www.cambridge.org/core/serv..._and_crossing_surface_gravity_wave_groups.pdf.

Looking at the difference in authors, it would seem that McAllister has just moved his work to Oxford, working in collaboration with his existing partners there & at the University of Western Australia, hence the introduction of a new contact at Edinburgh. Having visited the Oxford Dept. of Engineering Sciences (a truly hideous building), I seem to recall they were very proud of their wave dynamics research, so suspect they have assisted with some of the theory or simulation but not had the experimental resources of Edinburgh to back it up.
 
weustace said:
Looking at the difference in authors, it would seem that McAllister has just moved his work to Oxford, working in collaboration with his existing partners there & at the University of Western Australia, hence the introduction of a new contact at Edinburgh. Having visited the Oxford Dept. of Engineering Sciences (a truly hideous building), I seem to recall they were very proud of their wave dynamics research, so suspect they have assisted with some of the theory or simulation but not had the experimental resources of Edinburgh to back it up.
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Unless things have changed radically, Oxford's experimental fluids stuff is almost all wind tunnels - they do a huge amount of research into gas turbine blades and particularly into cooling of them. Big wave tanks are very expensive, and scientists tend to share toys like that.
 
Scientists bah what would they know fiddling around adding up a few numbers and splashing about in a pond any idiot can see that the sea is bumpy for goodness sake there are people on this forum that could do all that without getting off their arses and not even knowing the slightest thing about it.

I blame Brexit, lawyers, Margaret thatcher and global warming.
 
awol said:
Apart from the thread title what has Oxford got to do with it? Spokesman and tank are at UoE.
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If you read the short article it explains all. However, the research was carried out by the University of Oxford, they used a tank in Edinburgh that can generate waves from multiple directions, which is a rare thing, apparently.
 
Flying into Edinburgh, you get a very close view of the sea and shore line. There is along sea wall at Port Seaton / Cockenzie and when the wind is in the NW it is a lee shore. The wave pattern of the reflected and refracted waves is very obvious and what surprised me was the distance back upwind and outwards that was disturbed by the reflected and refracted waves. I estimate that it was at least 3 miles. The wave construct / destruct wave pattern was very noticeable compared to the linear waves blowing down to the wall from the Kirkcaldy side. The water was also much darker suggesting a rougher sea state.
 
Thanks. Leaving aside the maths which is beyond me, is this particular mechanism in essence like oblique/partial clapotis but with independent wave trains meeting at 120 degrees, rather than a wave train meeting its reflection and forming a standing wave?

(I have so far just skimmed the paper, and not checked if the 120 degree angle of train incidence is a real point of maximum interaction or just the largest angle they investigated, such that yet bigger effects might be found at even larger angles.)
 
Mustn't it be true that, for every big freak wave there must be a corresponding freakishly small wave?

I've always understood it that freak waves are inevitable, given at least two superimposed wave trains which interfere with each other. Sometimes the crests occur in the same place at the same time, so doubling the height.
Sometimes a trough must meet a crest, resulting in a calm spot.
Very interesting film though.
 
Ladybirdgaffcutter said:
Mustn't it be true that, for every big freak wave there must be a corresponding freakishly small wave?.
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I think what they are interested is not just the freakishly big - which is simple statistics - but the freakishly big and breaking. Normally waves only break when they smell the bottom - wave speed increases as the water gets deeper, so when a wave gets to water of a similar depth to its own amplitude, the crest travels faster than the trough and the wave breaks.

Something which breaks without that is interesting because it means another mechanism is at work.
 
savageseadog said:
The last time I saw something relating to freak waves it was suggested that Schrodinger's wave equation provided a mathematical model for waves in the sea. I've studied quantum physics so understand the wave equation but the Oxford work doesn't seem to mention it.
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It seems a bit far-fetched (ha-ha). Schrödingers wave equation describes the probability density of a single particle being somewhere, not the possibility of a super-large particle appearing from nowhere. I suspect that someone has seen "probability" and "waves" together and jumped to a conclusion.

Mind you, it would save a lot in canal fees if we could tunnel from Ardrishaig to Crinan ...
 
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