. . . Rogue waves seem to occur in deep water or where a number of physical factors such as strong winds and fast currents converge. This may have a focusing effect, which can cause a number of waves to join together. Such conditions exist along Africa’s wild coast, where strong winds blowing from the north-west interact with the swift and narrow Agulhas current flowing down the coast to produce enormous waves. Dr Heller, who likes to sail, says there may be other mechanisms at work too, including an interference effect that causes different ocean swells, travelling at different speeds, to add up to produce a rogue, and a non-linear effect in which a small change in something like wind direction or speed causes a disproportionately large wave.This article reports the research of Eric Heller of Harvard University and Lev Kaplan of Tulane University using microwaves to create laboratory modeling which appears semi-plausible but has not received a lot of media attentions yet. Granted that other than actual measurements, freaque waves are impossible to model with any degree of conceivability. Heller at least did not purport to solve the case, only portend the production of some "anecdotal evidence." I applaud the works of Heller's group. I think they are doing research in the spirit of doing research, not eager to send snesational new releases for media attention!
To study the phenomenon the group created a platform measuring 26cm by 36cm on which they randomly placed around 60 small brass cones to mimic random eddies in ocean currents. When microwaves were beamed at the platform, the researchers found that hot spots (the microwave equivalent of rogue waves) appeared far more often than conventional wave theory would predict; they were between ten and 100 times more likely.
Dr Heller says the results tend to support anecdotal evidence from seamen that rogue waves are not as rare as once thought. He thinks the work could also be used to understand more about the formation of these dangerous waves, perhaps to the point where it would one day be possible to provide a warning in places where rogue waves may be prone to appear. Seafarers would be thankful for that.
Saturday, September 26, 2009
Laboratory model of freaque waves with microwaves
Over a week ago, the Economist magazine in its Science & Technology section published an article entitled "Monsters of the deep" that has these to say: