Difference between revisions of "Waves"
(→Describing Waves) |
(→Rogue Waves) |
||
| (10 intermediate revisions by the same user not shown) | |||
| Line 27: | Line 27: | ||
==Rogue Waves== | ==Rogue Waves== | ||
| + | |||
| + | [https://en.wikipedia.org/wiki/Rogue_wave Rogue waves] are unusually tall waves that appear spontaneously on the open ocean. Their source remains somewhat of a mystery, but rogue waves are a topic of significant scientific and mathematical study due to the damage they cause to ships, platforms, etc. Rogue waves are capable of sinking, and have sunken even very large ships. | ||
| + | |||
| + | Recent research finds new ways to model and possibly predict them as described in a Quanta Magazine article from February 2020 titled [https://www.quantamagazine.org/the-grand-unified-theory-of-rogue-waves-20200205/ "The Grand Unified Theory of Rogue Waves"]. The article summarizes both Linear Addition and Nonlinear Focusing theories and describes a new way to combine both into a new theory. | ||
| + | |||
| + | The Dashews describe a Linear Addition theory: | ||
"There really is no such thing as a rogue wave. These larger than normal seas are the result of two wave trains coinciding at just the right moment for their energy to combine. When this happens the higher-than-normal crest is exposed to more wind force and absorbs additional energy. And if the wave happens to be unstable and breaks - because the rotating particles within the wave can no longer make it over the top - there will be a large mass of water falling downhill." | "There really is no such thing as a rogue wave. These larger than normal seas are the result of two wave trains coinciding at just the right moment for their energy to combine. When this happens the higher-than-normal crest is exposed to more wind force and absorbs additional energy. And if the wave happens to be unstable and breaks - because the rotating particles within the wave can no longer make it over the top - there will be a large mass of water falling downhill." | ||
Latest revision as of 06:29, 9 January 2021
- Excellent resource: WikiWaves
- Some background on ocean surface waves and also waves for oceanographers
- More background here.
- A lot of math on breakwaters at artificialreefs.org.
- Floating breakwaters by WhisprWave.
- Clickets
- Opening and closing tubes
- A moored device (Patent)
- A lot more patents at FreePatentsOnline (free registration required to see pictures)
- Wikipedia Sea state - standard classifications for wave state
- Beaufort scale - scale for wind and waves
Describing Waves
During the service life of an offshore structure, it will experience a huge number of waves, from very small wavelets to possibly giant waves. A practical way to describe these unceasingly changing waves
is to divide them into various categories (sea states), and use short-term wave statistics to depict each sea state and long-term wave statistics, usually in the form of a wave scatter diagram and rosette, to delineate the rate at which a sea state occurs.
In a similar way, there are two levels in the description of wave directionality, i.e., wave directional spectrum or wave spreading for short-term, and wave rosette for long-term, respectively.
See Section 3 of ABS GUIDANCE NOTES ON SPECTRAL-BASED FATIGUE ANALYSIS FOR FLOATING OFFSHORE STRUCTURES . 2005 for further discussion of Wave measurement.
Map of wave heights: https://static1.squarespace.com/static/57070436f699bbcfa154423d/t/583b353b725e257a97db2cfe/1480275484044/?format=750w
Rogue Waves
Rogue waves are unusually tall waves that appear spontaneously on the open ocean. Their source remains somewhat of a mystery, but rogue waves are a topic of significant scientific and mathematical study due to the damage they cause to ships, platforms, etc. Rogue waves are capable of sinking, and have sunken even very large ships.
Recent research finds new ways to model and possibly predict them as described in a Quanta Magazine article from February 2020 titled "The Grand Unified Theory of Rogue Waves". The article summarizes both Linear Addition and Nonlinear Focusing theories and describes a new way to combine both into a new theory.
The Dashews describe a Linear Addition theory:
"There really is no such thing as a rogue wave. These larger than normal seas are the result of two wave trains coinciding at just the right moment for their energy to combine. When this happens the higher-than-normal crest is exposed to more wind force and absorbs additional energy. And if the wave happens to be unstable and breaks - because the rotating particles within the wave can no longer make it over the top - there will be a large mass of water falling downhill."
From "Surviving the Storm" by Steve & Linda Dashew, page 241.
See also
- Rogue waves
| Ocean Environment |
|---|
| General · Waves · Sea state · Currents · Wind · Politics · Piracy · Biofouling |
