Tens tsunamis with sound waves under water

Underwater sound waves may be able to protect against tsunamis. By sending two sound waves on a tsunami, the energy of the huge water wave can be distributed differently, and it can weaken. Researchers in the field of applied mathematics have calculated this to Cardiff University. She write about it In the scientific journal Fluid Mechanics.

Acoustic waves move through the water by pressing it together and stretching, similar to how sound moves through the air. These waves move so much faster than the wave of the water surface (the movement that makes the water under the influence of wind and gravity), which for a long time not much was sought between the two types of waves. But there are all kinds of non-linear interactions between the different types of waves, lead researcher Usama Kadri have already discovered.

He showed almost ten years ago that two surface waves move against each other 95 percent of their energy lose And that that energy is converted into an acoustic wave. Kadri is also with the idea of ​​influencing tsunamis with sound waves longer.

The new research includes the non-linear interaction between two acoustic waves and one surface wave (the tsunami) in constant water depth. The researchers looked at the circumstances in which so-called resonant triade interaction is created. The three waves are then coordinated that energy transfer takes place. Whether this happens depends on, among other things, the amplitudes of the three waves and the wavelengths.

Counterproductive effect

The result of this resonance is that the amplitude (height) of the surface wave changes. If the tsunami weakens, the sound waves strengthen. The other way around it also works, that would have a counterproductive effect. The approach with two waves appears to be necessary, with one sound wave the surface wave can only be strengthened, the calculations showed.

An important conclusion is also that the efficiency of energy transfer is highly dependent on the water depth. More energy transfer takes place in shallow water than with deep water. This is a hopeful invention, because tsunamis are dangerous in shallow water.

The practical technology to tackle tsunamis with this idea should still be fully developed. Acoustic wave generators do exist for research applications, which should be scaled up enormously. It is more difficult that real-time information about the characteristics of the tsunami is also needed. The researchers are only now going to work with lobe extremiments.

Because the technology also works to increase waves, very different use of sound waves is also conceivable: generating energy with waves. Especially in deep water, such an approach has been difficult to get efficient so far, the use of sound waves can perhaps improve.

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