Rapid ships may be on the horizon after developing a slippery surface inspired by fish and seaweed to reduce the stretch of the hull in the water
- Resistance to water can be reduced in small lubricated cavities on the hull of a ship
- Long-haul cargo ships fight massive amounts of fuel ‘fluid friction’.
- Slippery fish and seaweed inspired design can help cut through water faster
Scientists say that the coating of mucus produced by fish and seaweed may reduce water resistance on ships.
Korean researchers designed a lubricant-infected surface intended to cover the hull of a ship, covered with small cavities.
As the cavities are constantly lubricated, a layer is formed on the surface which helps in easy slipping of water.
Computer simulations have shown that the coating can cut ‘fluid friction’ by about a fifth, experts say.
Slippery coatings would mean that ships would require less power during long-distance travel, which would mean less fuel to burn.
An X-ray image of a loach mucus storage system, and a schematic diagram showing how lubrication is secreted in the authors’ setup
“Our investigation of the hydrodynamics of a lubricating layer with a slippery surface in a basic configuration has provided important information,” a researcher quoted the researchers in his paper. ”
‘Further research on layers of mucus is expected to encourage improvements in energy-saving technology.’
Long-haul cargo ships lose propulsion power due to fluid friction, which is due to their large thin surfaces exposed to seawater.
However, the hydrodynamics of lubricant-affected surfaces is ‘not yet fully understood’, the team says.
The group looked at the average speed of a cargo ship with realistic material properties and simulated how it behaved under different lubrication setups
Experts at the Korea Advanced Institute of Science and Technology and Pohang University of Science and Technology looked at the average speed of a cargo ship with realistic material properties, such as density and surface tension.
They then investigated how the size of the cavities in the particular material and the thickness of their ‘lids’ affected the amount of drag on the ship.
They found that for large open areas, the lubricant is more diffuse than small open areas, leading to a more slippery surface.
On the other hand, the thickness of the lid was not found to have much effect on resistance, although a thicker lid formed a thicker lubricant build-up layer.
Researchers believe that the breakdown of the physics of various types of cavities will help in the implementation of real-life marine vehicles.
The study’s author Hyung Jin Sung said, “The drag reduction rate will increase substantially if current design criteria are adopted.”
Because drag increases with speed, the faster the ship moves, the more fuel the resulting resistance must withstand.
Therefore the physics behind the technology will help save the planet by affecting how much fuel the ship needs.
This can help reduce the emission of potentially harmful sulfur compounds and CO2 resulting from the exhaust of the power propeller.
The study has been published in Physics of Fluids.
Why are fish and seeded?
Fish secrete a type of mucus from their skin.
This mud coating is important because it provides protection from parasites and diseases, covers wounds to prevent infection and helps fish move faster through water.
Some species release toxins in their sludge that release the attacking organisms, while others use their sludge to feed their children.
The mechanism of fish mucus drag reduction is one of several adaptations to facilitate movement.
Seaweed also feels thin to the touch due to its jelly-like layer on its surface.
This keeps the plants suppressed and protects the seaweed from being damaged by the waves.
Researchers have taken inspiration from marine life to overcome water resistance to man-made objects.
Source: Marine Scotland