Why do ducklings swim in a straight line?

As the old saying goes: a person's name reflects his character. People whose names contain the character "鱼" (fish) will also have a strong preference for fish. For example, a professor named Frank Fish said that he also likes fish.

However, this "Fish Professor" Frank Fish not only loves fish, but also ducks in the water. As a biology professor, his main research direction is the dynamics of animal movement . In 1994, Professor Frank published an article on duck swimming, studying the energy consumption of ducks when swimming in formation.

But the research on duck-duck swimming is not over yet. In 2021, Dr. Zhiming Yuan's research team published a new duck-duck swimming paper. These two studies jointly won this year's Ig Nobel Prize in Physics.

Dr. Yuan Zhiming introduces the Duck Parade in the Ig Nobel Prize丨Ig Nobel Prize

Ducks swimming, what is the fascinating magic that makes researchers "obsessed" with it?

One Duck One Duck Tour丨Satya Prakash Karan/Youtube

Duck riding the waves

In the talent show, each team's stage performance is very particular about the positioning of the team, and the "water performance stage" of YaYa is no exception. The "one" shape is simply the standard formation of the YaYa team.

Follow the tour丨Vicki Jauron/Babylon and Beyond Photography

The reason why ducks like to "line up" is still under study, but the benefits of this formation are gradually emerging: saving effort. It can be said that "it is not because of saving effort that people line up, but because of lining up that they save effort."

Wild ducks in an experimental setup, researchers measure oxygen consumption to calculate metabolic rate | Reference [2]

Frank "trained" several one-day-old wild ducks in the study so that they could swim with female ducks in the experimental device. Then, they conducted experimental measurements on ducks grown to 3 days, 7 days and 14 days. Metabolic measurements of the ducks showed that as the number of ducklings in the row increased, the energy consumption of each duckling decreased. This experiment proved the hypothesis of energy consumption in the procession movement from a metabolic perspective .

The reason behind saving effort is because of “waves”.

Dr. Yuan Zhiming and others observed the ducks for seven years and established a related mathematical model, discovering the wave secrets of the ducks' swimming.

Force diagram of a duck in still water with the same wavelength but different phases. (The green curve represents the water surface, the blue curve represents the pressure on the duckling’s body surface, and the arrow represents the direction of the force) | Reference [3]

In the "line formation", when the duckling is in the most appropriate position behind the mother duck, the wave resistance at this time will become "positive" - ​​the direction of the resistance becomes the same direction as the duckling, and the phase of the wave at this time is as shown in Figure d above. In other words, the resistance at this time actually becomes a thrust from the back to the front, "pushing" the duckling to ride the wind and waves. More subtly, this situation can be maintained by the ducklings in the formation. The first and second ducklings behind the big duck are both pushed, so that they can move forward with less effort. From the third duckling to the end, the force on the individual will gradually approach zero, thus achieving a dynamic balance.

Marching in a procession | Martin Diebel/Discovery

There is no such thing as a peaceful life, it's just that there is a duck carrying the burden for you. This wave-riding and wave-passing mechanism allows the ducklings swimming with the big duck to swim smoothly.

Ducks save energy, boats save fuel

There are not only ducks swimming in the water, but also boats. Since ducks are so smart, humans must also inject some wisdom into boats.

The research team of Wuhan University of Technology analyzed different ship formation configurations and found that the total resistance coefficient of the tandem fleet formation was effectively reduced, which means it is more energy-efficient.

Thinking further ahead, is it possible that there will be an entire sea train in the future... Dr. Yuan Zhiming's team is actually studying related concepts, hoping to improve the efficiency of maritime transportation.

Who doesn’t look forward to the sea train in “One Piece” becoming a reality?

Smoky Tom Sea Train丨One Piece Wiki

References

[1] Fish, Fish, Fish - Improbable Research. https://improbable.com/airchives/paperair/volume12/v12i3/Fish-v12i3.pdf

[2]Fish, Frank E. "Energy conservation by formation swimming: metabolic evidence from ducklings." Mechanics and physiology of animal swimming (1994): 193-204.

[3]Yuan, Zhi-Ming, et al. "Wave-riding and wave-passing by ducklings in formation swimming." Journal of Fluid Mechanics 928 (2021).

[4] Why do ducks form a straight line when crossing a river? Intellectuals. http://zhishifenzi.blog.caixin.com/archives/250888

[5] He, Yangying, et al. "Will sailing in formation reduce energy consumption? Numerical prediction of resistance for ships in different formation configurations." Applied Energy 312 (2022): 118695.

Author: Owl

Edit: Window knocking rain

Title image: Robyn Beck/Discovery

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