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Draw on the wisdom of nature - tuna and ship paint

draw on the wisdom of nature - tuna and ship paint

May 31, 2012

[China paint information] it is said that large tuna can swim at a speed of 80km/h in the ocean (Figure 1). Tuna is indeed a streamline shape with fast swimming speed, but in addition, there should be other tricks that can reduce the frictional resistance of water. One product came out of this idea. That is the antifouling bottom coating "LF sea" developed by Nippon marine coatings (Headquarters: Kobe)

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Figure 1: Tuna swimming in the sea

the speed of tuna is said to be as high as 80km/h. And the body surface is covered with mucous membrane instead of fish scales

the secret lies in the mucous membrane on the surface

the tuna that keeps swimming at high speed has no scales, and its body surface is covered with sticky mucous membrane. Although the details are still unknown, it is believed that the friction resistance of the turbulent boundary layer will be weakened under the action of this kind of mucosa. In fact, the retention rate of better mechanical properties and the melt viscosity are low (compared with the traditional nylon 66). Studies have shown that after adding a very small amount of polymer to the liquid, the turbulent liquid friction resistance will weaken. The stiffness of our anechoic hood will be increased by 4 times and 6 times at room temperature and the working temperature of the rear muffler respectively. Note that (Thomas effect), it may also belong to the same phenomenon on the body surface of tuna

"because I am engaged in the development of ship bottom paint, I often think about whether I can get the inspiration of developing products from fish and marine organisms", Naoki Yamamori, executive director of Nippon marine paint technology headquarters, has his eyes on tuna. When the ship is sailing, the friction of the bottom surface contacting the sea water accounts for 50 ~ 80% of the total resistance. According to shansheng's idea, if the ship can realize the liquid-liquid contact between the mucous membrane and the sea water, rather than the direct contact between the solid (bottom of the ship) and the sea water, it should be able to reduce the resistance

for this reason, shansheng adopted the method of adding high hydrophilic and viscous hydrogel into the bottom coating to reduce the friction with water. The bridged polymer in hydrogel can form three-dimensional eyes early enough to store water in the eyes. In daily life, kelp soup and agar also belong to this category

in this way, lf sea, which not only does not damage the fundamental purpose of the bottom coating to prevent the attachment of barnacles and other aquatic organisms, but also reduces the friction resistance of seawater, came into being. It is confirmed that the ferry with this coating can save about 3.4% fuel consumption (Figure 2). Although it is only 3.4%, it can save about 10million to 20million yen in fuel cost. Therefore, since it was put into operation in 2008, it has been used by more than 00 ships mainly in building materials, automobile industry, packaging and transportation of goods, decoration materials and daily necessities *1

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Figure 2: the car carrier and sample steel plate sprayed with LF sea

the red part is coated with bottom paint (a). From the sprayed sample, it can be seen that there are bumps (b) on the surface