Decoding dangerous rogue waves that threaten offshore ships

American scientists have decoded the mystery of rogue waves - violent, sudden waves that can endanger ships and offshore structures.

A team of scientists from the Georgia Institute of Technology, USA, have studied rogue waves and discovered that they are formed naturally when waves follow each other and amplify each other. They used data from the North Sea to conclude that rogue waves do not arise from strange forces and are developing a model that can predict this dangerous wave in the future. Photo: Shutterstock.

On New Year’s Day 1995, a giant 24.4m rogue wave crashed onto the Draupner oil platform in the North Sea. The massive wall of water collapsed steel railings and tossed heavy equipment on deck. It was the first time researchers had measured the height of a rogue wave offshore. Photo: SciTechDaily.com.

“This confirms what sailors have been describing for centuries. They always talked about waves that appeared suddenly and were very large. But for a long time, we thought it was just a myth,” said Francesco Fedele, associate professor of civil and environmental engineering at the Georgia Institute of Technology. Photo: Professor Alessandro Toffoli.

Associate Professor Fedele led an international team to investigate the origins of rogue waves. They analysed 27,500 rogue wave records collected over 18 years in the North Sea – the most comprehensive dataset of its kind. Photo: REB Images/Tetra Images/Getty Images.

Each record detailed the rogue wave activity for 30 minutes, including height, frequency, and direction. The team's conclusions challenge the long-held assumption that the mechanism for rogue wave generation is a phenomenon called "modulation instability." Photo: Personnel of NOAA ship 'Delaware II,' Flickr // CC BY 2.0.

“Modular instability” is a process where small changes in the timing and spacing of waves cause energy to be concentrated in a single wave. Instead of being evenly distributed, the wave pattern changes, causing one wave to suddenly become much larger than the others. Photo: Guy Edwardes/naturepl.com.

Associate Professor Fedele points out that modulation instability “is mainly true when waves are confined in channels that cause energy to flow in only one direction. However, in the open sea, energy can spread in many directions.” Photo: Alexander Izmaylov/iStock/Getty Images Plus.

When Associate Professor Fedele and colleagues analyzed data from the North Sea, they found no evidence of modulated instability in rogue waves. Instead, they discovered that the largest waves appeared to be the product of two simpler effects. Photo: Ryan Janssens/Shutterstock | The Daily Galaxy --Great Discoveries Channel.

The first effect, called translational convergence, occurs when waves traveling at different speeds and directions happen to align at the same time and place. They stack up, creating a wave crest that is much higher than normal. The second effect, called quadratic constraint non-translation, naturally stretches the shape of the wave, making the crest 15-20% higher. Photo: passporthealthusa.

Associate Professor Fedele explained that when the two effects occur together, a wave is much larger. This discovery has many implications for developing models to predict the threat of rogue waves to ships and offshore structures. In the future, scientists will be able to predict when and where rogue waves are likely to strike and have solutions to deal with them. Photo: SciTechDaily.com.

Readers are invited to watch the video : Behind the success of scientists. Source: VTV24.

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