Sea Monkeys Show Scientists How To Rewrite a Rule of Turbulence

In Lei Fang’s lab at the University of Pittsburgh, a brine shrimp swims through a two-dimensional turbulent system.

在匹兹堡大学雷方的实验室里，丰年虾在二维湍流系统中游动。

Xinyu Si/University of Pittsburgh

司新宇/匹兹堡大学

In the 1960s and ’70s, colorful comic book advertisements from the Transcience Corporation in New York City promised to mail anyone who sent cash, check, or money order a “bowlfull of happiness” — in reality, a small paper envelope of freeze-dried eggs.

在 20 世纪 60 年代和 70 年代，纽约市 Transscience Corporation 的彩色漫画广告承诺向任何寄出现金、支票或汇票的人寄出“满满一碗幸福”——实际上是一个装有冻干鸡蛋的小纸信封。

Dropped into salt water, the eggs would produce brine shrimp, also known as sea monkeys.

将卵放入盐水中，会产生丰年虾，也称为海猴。

Brine shrimp are about a centimeter long and swim upside down, beating their legs madly and trailing their elongated abdomens behind them like tails.

丰年虾长约一厘米，倒立游动，疯狂地拍打腿，细长的腹部像尾巴一样拖在身后。

As scientists recently learned, these tiny swimmers can do more than just move themselves.

正如科学家最近了解到的那样，这些微小的游泳者不仅仅可以自己移动。

Researchers have long thought that in a turbulent system like a current of water, energy flows in only one direction, from larger scales to smaller ones, or vice versa, depending on the system’s dimensions.

研究人员长期以来一直认为，在像水流这样的湍流系统中，能量仅沿一个方向流动，从较大尺度流向较小尺度，反之亦然，具体取决于系统的尺寸。

But in observing the humble brine shrimp, scientists at the University of Pittsburgh realized that — with just a tiny adjustment — the flow of energy could be reversed.

但在观察不起眼的丰年虾时，匹兹堡大学的科学家们意识到，只需进行微小的调整，能量的流动就可以逆转。

With a simple tweak, scientists can reverse the energy flow of turbulence in a 2D system.

通过简单的调整，科学家们就可以逆转二维系统中湍流的能量流。

The scientists discovered that they could direct the cascade of energy in a two-dimensional system by disrupting the system’s flow with a small obstacle, as long as it was angled just right.

科学家们发现，他们可以通过用一个小障碍物扰乱系统的流动来引导二维系统中的能量级联，只要它的角度恰到好处。

“The geometry matters,” said Lei Fang , the Pittsburgh engineer who led the new study.

“几何形状很重要，”领导这项新研究的匹兹堡工程师雷方说。

The discovery capitalized on a fundamental, if often unrecognized, mathematical description of how forces interact to push energy through a system, said Gregory Falkovich, a physicist at the Weizmann Institute of Science and a pioneer in the study of turbulent two-dimensional systems.

魏茨曼科学研究所的物理学家、湍流二维系统研究的先驱格雷戈里·法尔科维奇说，这一发现利用了一种基本的、尽管常常未被认识到的数学描述，即力如何相互作用，以推动能量通过系统。

“This is a beautiful and skillful experimental work.”

“这是一件美丽而巧妙的实验作品。”

These findings could extend to larger, more chaotic systems, including those in three dimensions.

这些发现可以扩展到更大、更混乱的系统，包括三维系统。

The work has implications for our understanding of fluid dynamics and may have applications in areas such as pollution control and drug design.

这项工作对我们对流体动力学的理解具有重要意义，并可能在污染控制和药物设计等领域得到应用。

Brine shrimp are tiny invertebrates that inhabit waters with high salt concentration.

丰年虾是微小的无脊椎动物，栖息在高盐浓度的水域中。

They grow to about 10 millimeters long, the width of a pencil eraser.

它们长到大约 10 毫米长，相当于铅笔橡皮的宽度。

Turbulence is hard to miss.

湍流很难被忽视。

It stirs the raucous foam at the base of a waterfall and shapes the crest of a breaking wave.

它搅动瀑布底部沙哑的泡沫，塑造破碎波浪的波峰。

It’s behind the bumpiness of a flight, the swirls of milk in a cup of coffee, and the roil of plasma on the surface of the sun.

它隐藏在飞行的颠簸、一杯咖啡中牛奶的漩涡以及太阳表面等离子体的翻滚之中。

“We observe turbulence generally everywhere in our lives, when we go to the beach or wash our hands,” said Francesca De Serio , a civil engineer and expert on hydrodynamics at the Polytechnic University of Bari in Italy.

意大利巴里理工大学土木工程师兼流体动力学专家弗朗西斯卡·德塞里奥（Francesca De Serio）表示：“当我们去海滩或洗手时，我们生活中到处都会观察到湍流。”

We observe turbulence generally everywhere in our lives, when we go to the beach or wash our hands.

当我们去海滩或洗手时，我们在生活中随处可见湍流。

Francesca De Serio, Polytechnic University of Bari

Francesca De Serio，巴里理工大学

A turbulent system is complicated, characterized by complex forces and inner turmoil.

湍流系统是复杂的，其特征是复杂的力和内部的动荡。

But it can start simply enough.

但它可以很简单地开始。

For example, turbulence arises when a flowing fluid encounters an obstacle that changes the velocity of part of the flow.

例如，当流动的流体遇到改变部分流动速度的障碍物时，就会产生湍流。

In a river, water slows down by the bank due to friction, and the velocity mismatches can produce vortices or eddies.

在河流中，水流由于摩擦而在河岸处减速，速度不匹配会产生漩涡或漩涡。

When a river divides to move around a rock, speeds change and voids form; water falls over itself and may start to rotate.

当河流分流绕过岩石时，速度会发生变化并形成空隙；水会自行落下并可能开始旋转。

Air, too, is a fluid, its turbulence produced by competing currents and changing temperatures.

空气也是一种流体，它的湍流是由竞争的水流和变化的温度产生的。

In such a system, energy moves between size scales.

在这样的系统中，能量在尺寸尺度之间移动。

English mathematician and physicist Lewis Fry Richardson, the founder of modern weather forecasting, discovered this when he studied the fluid systems formed by gases in the atmosphere.

现代天气预报的创始人、英国数学家和物理学家刘易斯·弗莱·理查森在研究大气中气体形成的流体系统时发现了这一点。

He found that the kinetic energy of a large eddy feeds into smaller and smaller eddies, until it reaches the scale where viscosity, which resists motion, takes over.

他发现，大涡流的动能会流入越来越小的涡流，直到达到阻碍运动的粘度接管的规模。

The energy is ultimately dissipated as heat.

能量最终以热量的形式耗散。

In 1922, Richardson captured the concept in verse:

1922 年，理查森用诗句表达了这个概念：

Big whorls have little whorls Which feed on their velocity, And little whorls have lesser whorls And so on to viscosity.

大螺纹有小螺纹，它们以速度为食，小螺纹有较小的螺纹，依此类推。

Starting in the early 1940s, the Soviet mathematician Andrey Kolmogorov provided a clear and rigorous mathematical foundation for the study of turbulence.

从 20 世纪 40 年代初开始，苏联数学家安德烈·柯尔莫哥洛夫 (Andrey Kolmogorov) 为湍流研究提供了清晰而严格的数学基础。

But his work, like Richardson’s, mainly focused on three-dimensional systems in which energy flows from large features to small ones.

但他的工作和理查森一样，主要集中在三维系统上，其中能量从大特征流向小特征。

In the late 1960s, the physicists Robert Kraichnan and George Batchelor extended the investigation to two-dimensional systems.

20 世纪 60 年代末，物理学家 Robert Kraichnan 和 George Batchelor 将研究范围扩展到了二维系统。

Two-dimensional turbulent systems include phenomena like Jupiter’s Great Red Spot, which swirls so violently that it overwhelms any motion farther down in the atmosphere.

二维湍流系统包括像木星大红斑这样的现象，它的旋转如此剧烈，以至于压倒了大气层中更深处的任何运动。

This type of two-dimensional turbulent system transfers energy from one scale to another, like a three-dimensional one, but with a twist: The energy of a two-dimensional turbulent system cascades in the opposite direction, moving from small eddies up to large ones.

这种类型的二维湍流系统将能量从一个尺度转移到另一个尺度，就像三维尺度一样，但有一个扭曲：二维湍流系统的能量以相反的方向级联，从小涡流移动到大涡流。

In Jupiter’s Great Red Spot, smaller eddies and vortices near the perimeter feed the giant maelstrom in the center.

在木星的大红斑中，周边附近的较小漩涡和旋涡为中心的巨大漩涡提供了能量。

In the decades after those pioneering studies reported an inverse flux in two-dimensional systems, physicists did not deeply interrogate whether those flows were fixed.

在这些开创性研究报告二维系统中存在逆流之后的几十年里，物理学家并没有深入探讨这些流是否是固定的。

The underlying energy mechanisms of two-dimensional turbulent systems certainly weren’t on the mind of Xinyu Si around 2021, when he started investigating brine shrimp as a student in Fang’s lab.

2021 年左右，当新宇还是方实验室的学生时，他开始研究丰年虾，当时他肯定没有想到二维湍流系统的潜在能量机制。

Fang’s lab focuses on “active matter,” a physics term describing things that move by themselves and inject energy into their environments.

方的实验室专注于“活性物质”，这是一个物理术语，描述自行移动并向环境注入能量的物体。

It’s a label broad enough to include networks of living things, like bacteria, and nonliving things, like tiny robots.

这是一个足够广泛的标签，可以包括细菌等生物网络和微型机器人等非生物网络。

In this project, Si and Fang were interested in investigating how biological swimmers mix materials in fluids where turbulence shows up.

在这个项目中，Si 和 Fang 有兴趣研究生物游泳者如何在出现湍流的流体中混合材料。

The researchers had hypothesized that, in the mixing of fluids in large natural systems, turbulence generated by tiny organisms plays an underappreciated role.

研究人员假设，在大型自然系统中的流体混合中，微小生物体产生的湍流发挥着未被充分认识的作用。

Billions of minuscule creatures, after all, agitate the waterways of the world.

毕竟，数十亿微小生物扰动着世界的水道。

Xinyu Si, now a postdoc at the University of Rochester, prepares a research tank.

斯新宇现在是罗切斯特大学的博士后，他正在准备一个研究池。

J.

J。

Adam Fenster/University of Rochester

亚当·芬斯特/罗切斯特大学

To closely study this in a simple model, Si poured a thin film of salt water over a glass surface in a tank and positioned magnets underneath.

为了在一个简单的模型中仔细研究这一点，Si 在水箱的玻璃表面上倒了一层盐水薄膜，并在下面放置了磁铁。

When he applied an electric current to the conductive fluid, it interacted with the magnets and created motion in the water, which flowed in one direction along one side of a channel and in the opposite direction along the other side.

当他向导电流体施加电流时，电流与磁铁相互作用并在水中产生运动，水沿着通道的一侧朝一个方向流动，沿着另一侧朝相反的方向流动。

This created a gradient of velocities across the center, to which Si added brine shrimp.

这在中心产生了速度梯度，Si 在其中添加了丰年虾。

When Si and Fang calculated how the shrimp’s flailing bodies disrupted the moving water, they saw “something very, very strange,” Fang said: The shrimp weren’t just contributing to the chaos of the system; they also seemed to be shifting the direction in which energy flowed.

当斯和方计算虾挥动的身体如何扰乱流动的水时，他们看到了“非常非常奇怪的事情”，方说：虾不仅造成了系统的混乱；它们还导致了系统的混乱。它们似乎也在改变能量流动的方向。

A turbulent system can be described in terms of how much it stretches and compresses the fluids within, due to the interactions of fluids flowing at different velocities.

由于以不同速度流动的流体的相互作用，湍流系统可以用其内部流体的拉伸和压缩程度来描述。

These dynamics show up, for example, when you pour confetti into a river and watch it organize into sweeping lines as it races on competing currents downstream.

例如，当你将五彩纸屑倒入河流中并观察它在下游竞争的水流中竞速时组织成横扫的线条时，这些动态就会显现出来。

Every experiment suggested the same conclusion: The orientation of a brine shrimp’s body seemed to change the turbulent system’s energy flux.

每个实验都得出相同的结论：丰年虾身体的方向似乎改变了湍流系统的能量通量。

Si and Fang ran the brine shrimp experiment repeatedly.

斯和方反复进行了丰年虾实验。

They found that when a solo shrimp swam at an angle of less than 45 degrees to the direction of maximum stretching, the energy flowed from smaller scales to larger ones, feeding the flow itself, as they’d predicted for a 2D system.

他们发现，当一只单独的虾以与最大拉伸方向小于 45 度的角度游动时，能量会从较小的鳞片流向较大的鳞片，从而为水流本身提供能量，正如他们对 2D 系统的预测一样。

But if the shrimp swam at an angle of more than 45 degrees to the direction of maximum stretching, the energy went in reverse, pulling from the larger scale of the flow to energize smaller perturbations.

但如果虾以与最大拉伸方向成 45 度以上的角度游动，能量就会反向流动，从较大规模的水流中拉动，以激发较小的扰动。

It appeared to be a clean about-face.

这看起来是一个干净的大转变。

Every experiment suggested the same conclusion: The orientation of a brine shrimp’s body seemed to change the turbulent system’s energy flux.

每个实验都得出相同的结论：丰年虾身体的方向似乎改变了湍流系统的能量通量。

The scientists found a way to interpret what they were seeing through a field of mathematics called tensor geometry, which has long been a workhorse for physicists studying turbulence.

科学家们找到了一种方法来解释他们通过称为张量几何的数学领域所看到的东西，该领域长期以来一直是物理学家研究湍流的主力。

A tensor is a mathematical tool that can help you measure something that changes in multiple ways at once.

张量是一种数学工具，可以帮助您测量同时以多种方式变化的事物。

For example, when you press down on a sponge, its sides bulge outward.

例如，当您按下海绵时，它的侧面会向外凸出。

A tensor can describe how stress — the weight of your hand — affects strain — the deformation of the sponge.

张量可以描述压力（手的重量）如何影响应变（海绵的变形）。

Tensors give fluid dynamics researchers a powerful way to model physical phenomena that can transform in terms of direction or strength.

张量为流体动力学研究人员提供了一种强大的方法来模拟可以在方向或强度方面发生变化的物理现象。

Fang and Si found that their brine-shrimp situation made sense if they looked at it as the interaction of two tensors in two dimensions.

Fang 和 Si 发现，如果将丰年虾的情况视为二维中两个张量的相互作用，那么他们的丰年虾情况就有意义了。

One tensor represented how shear — the large-scale movement of the water — affected energy flux.

一个张量代表剪切力（水的大规模运动）如何影响能量通量。

The other represented how the energy flux was shaped by small-scale movements from the swimmers.

另一个代表了游泳者的小规模运动如何塑造能量通量。

The orientation of the swimmer determined the alignment of the two tensors, and the alignment of the tensors determined how the energy flowed.

游泳者的方向决定了两个张量的对齐方式，而张量的对齐方式决定了能量如何流动。

As Fang and Si reported in 2024 , the angle between the brine shrimp’s body and the forces of the fluid could alter the direction of the energy flux.

正如 Fang 和 Si 在 2024 年报道的那样，丰年虾的身体和流体力之间的角度可能会改变能量流的方向。

Fang, an engineer at the University of Pittsburgh, is interested in the influence of biological swimmers in natural systems.

方是匹兹堡大学的工程师，他对生物游泳者对自然系统的影响感兴趣。

Si had been releasing brine shrimp into the tank, pointing a camera at them, and patiently waiting until one swam through the test area at just the right angle.

斯一直在将丰年虾放入水箱中，用相机对着它们，耐心地等待一只丰年虾以正确的角度游过测试区域。

In the next iteration of the experiment, Si and Fang replaced the brine shrimp with an array of centimeter-long rods, which proved easier to measure.

在下一次实验中，Si 和 Fang 用一系列厘米长的棒代替了丰年虾，事实证明这更容易测量。

They found that, by altering the orientation of the rods relative to the flow, they were able to control whether energy transferred to higher or lower scales.

他们发现，通过改变棒相对于流动的方向，他们能够控制能量是否转移到更高或更低的尺度。

The findings held even when Si and Fang invited the scrutiny of two other scientists: Filippo De Lillo and Guido Boffetta of the University of Turin in Italy, whom Fang met at a conference.

即使斯和方邀请另外两位科学家——意大利都灵大学的菲利波·德利洛（Filippo De Lillo）和吉多·博菲塔（Guido Boffetta）——方在一次会议上认识的两位科学家——进行仔细研究，研究结果仍然成立。

In the outside experts’ numerical simulations, the same effect clearly showed up.

在外部专家的数值模拟中，同样的效果也清晰地显现出来。

“That made me much more comfortable,” Fang said, “because it’s a very weird thing to manipulate energy flux.”

“这让我舒服多了，”方说，“因为操纵能量通量是一件非常奇怪的事情。”

With renewed confidence, the researchers reported their findings in 2025.

带着新的信心，研究人员于 2025 年报告了他们的发现。

“It was interesting because they were saying that with small, specific interventions in the flow we can …

“这很有趣，因为他们说，通过对流程进行小的、具体的干预，我们可以……

show a transfer of energy between scales,” De Serio said.

显示尺度之间的能量转移，”德塞里奥说。

They demonstrated that with minimal manipulation, the energy flux in a 2D system can be steered to act more like (but not exactly like) the flux in a 3D one, which suggests that physicists might be able to apply insights from one dimensional domain to the other.

他们证明，通过最少的操作，2D 系统中的能量通量可以被引导为更像（但不完全相同）3D 系统中的通量，这表明物理学家可能能够将一维领域的见解应用到另一维领域。

There are confounding issues to overcome.

有一些令人困惑的问题需要克服。

In their experiments, Si and Fang used a shallow pool of fluid whose friction made turbulence hard to initiate.

在他们的实验中，Si 和 Fang 使用了一个浅水池，其摩擦力使湍流难以引发。

And there are big differences between a weakly turbulent two-dimensional system like the one in their lab and the strongly turbulent three-dimensional ones more commonly found in nature.

他们实验室中的弱湍流二维系统与自然界中更常见的强湍流三维系统之间存在很大差异。

Mathematically, though, there’s no reason the scientists’ observations shouldn’t extend to such scenarios.

不过，从数学角度来看，科学家的观察没有理由不扩展到这种情况。

Si and Fang are investigating the possibility, testing ideas on tabletop tornadoes.

Si 和 Fang 正在研究这种可能性，并测试桌面龙卷风的想法。

They’re also exploring how to influence the “transport barrier,” the threshold between two fluids as they mix.

他们还在探索如何影响“传输屏障”，即两种液体混合时之间的阈值。

According to Fang’s theory, disrupting this boundary — which could be useful in controlling pollution or mixing fluids for drug development — would use less than 1% of the energy required to keep the boundary intact.

根据 Fang 的理论，破坏这个边界——这可能有助于控制污染或混合流体用于药物开发——所消耗的能量不到保持边界完整所需的能量的 1%。

Other scientists have also begun experimenting with manipulating energy flux.

其他科学家也开始尝试操纵能量通量。

De Serio, at the Polytechnic University of Bari, has been firing strong jets into large tanks of turbulent, rotating fluids with high viscosity.

巴里理工大学的德塞里奥一直在向装有高粘度湍流、旋转流体的大型储罐发射强力射流。

“I was attracted by this idea that these [manipulations] could be applied in a real context,” she said.

“我被这些[操纵]可以应用于真实环境的想法所吸引，”她说。

In March 2026, she reported results from experiments conducted on a large rotating vortex manipulated with small, horizontal jets firing into the middle.

2026 年 3 月，她报告了通过向中间喷射小型水平射流来操纵大型旋转涡流进行的实验结果。

She observed patches of inverse energy flux that started out as intermittent bursts but grew steady with increasing rotation.

她观察到反向能量通量的斑块最初是间歇性的爆发，但随着旋转的增加而稳定增长。

Those findings, she says, may point to practical strategies for controlling energy pathways in real-world situations.

她说，这些发现可能为现实世界中控制能量路径的实用策略指明了方向。

Si, now a postdoc at the University of Rochester, said that the current work introduces a new hypothesis that’s testable in any setting where turbulence plays a role, from a tiny “bowlfull of happiness” to the enormous scale of Earth’s atmosphere.

现为罗切斯特大学博士后的斯说，当前的工作引入了一种新假设，该假设可以在任何湍流发挥作用的环境中进行测试，从微小的“装满幸福的碗”到巨大的地球大气层。

Turbulent systems may be notoriously difficult to understand, but what dictates the flow of energy may be an issue of simple geometry.

众所周知，湍流系统可能很难理解，但决定能量流动的可能是一个简单的几何问题。

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辱骂、亵渎、自我推销、误导、语无伦次或偏离主题的评论将被拒绝。

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