Tag Archives: fluid dynamics

Say ain’t so! van Gogh’s ‘The Starry Night’ is not a masterpiece when it comes to flow physics according to researchers

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Researchers at Virginia Commonwealth University (VCU; US) have challenged the findings in recent research that was highlighted here in a December 16, 2024 posting “van Gogh’s sky is alive with real-world physics.”

An April 1, 2025 news item (not an April Fool’s joke) on phys.org announces a conclusion that contradicts the original findings,

The Dutch master Vincent van Gogh may have painted one of Western history’s most enduring works, but “The Starry Night” is not a masterpiece of flow physics—despite recent attention to its captivating swirls, according to researchers from Virginia Commonwealth University and the University of Washington [state not district].

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Credit: Pixabay/CC0 Public Domain [downloaded from https://phys.org/news/2025-04-vincent-van-gogh-starry-night.html].

An April 1, 2025 Virginia Commonwealth University (VCU) news release (also on EurekAlert) by Leila Ugincius, which originated the news item, goes on to further refute the claim about Starry Night and flow physics, Note: Links have been removed,

The post-Impressionist artist painted the work (often referred to simply as “Starry Night”) in June 1889, and its depiction of a pre-sunrise sky and village was inspired in part by the view from van Gogh’s asylum room in southern France. The painting is part of the permanent collection of the Museum of Modern Art in New York City.

Last year, a paper published in the September issue of Physics of Fluids – “Hidden Turbulence in van Gogh’s ‘The Starry Night’” – received considerable notice by positing that the eddies, or swirls, painted by van Gogh adhere to Kolmogorov’s theory of turbulent flow, which explains how air and water swirls move in a somewhat chaotic pattern. “[van Gogh] was able to reproduce not only the size of whirls/eddies, but also their relative distance and intensity in his painting,” the paper read.

However, those conclusions are unfounded, according to Mohamed Gad-el-Hak, Ph.D., the Inez Caudill Eminent Professor in VCU’s Department of Mechanical and Nuclear Engineering, and James J. Riley, Ph.D., the inaugural Paccar Professor of Mechanical Engineering at the University of Washington. Their report –  “Is There Hidden Turbulence in Vincent van Gogh’s ‘The Starry Night’?” – appears in the latest issue of Journal of Turbulence.

Here’s a link to and a citation for the paper,

Is there hidden turbulence in Vincent van Gogh’s The Starry Night? by James J. Riley
& Mohamed Gad-el-Hak. Journal of Turbulence Pages 1–2. DOI: https://doi.org/10.1080/14685248.2025.2477244 Published online: 18 Mar 2025

This paper is behind a paywall.

van Gogh’s sky is alive with real-world physics

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Caption: The authors measured the relative scale and spacing of the whirling brush strokes in van Gogh’s “The Starry Night,” along with variances in luminance of the paint, to see if the laws that apply in the physics of real skies apply in the artist’s depiction. The results suggest van Gogh had an innate understanding of atmospheric dynamics. He captured multiple dimensions of atmospheric physics with surprising accuracy. Credit: Yinxiang Ma

A September 17, 2024 American Institute of Physics news release (also on EurekAlert) reveals how researchers in the fields of marine sciences and fluid dynamics have revealed the ‘hidden turbulence’ in van Gogh’s The Starry Night,

Vincent van Gogh’s painting “The Starry Night” depicts a swirling blue sky with yellow moon and stars. The sky is an explosion of colors and shapes, each star encapsulated in ripples of yellow, gleaming with light like reflections on water. 

Van Gogh’s brushstrokes create an illusion of sky movement so convincing it led atmospheric scientists to wonder how closely it aligns with the physics of real skies. While the atmospheric motion in the painting cannot be measured, the brushstrokes can.

In an article published this week in Physics of Fluids, by AIP Publishing, researchers specializing in marine sciences and fluid dynamics in China and France analyzed van Gogh’s painting to uncover what they call the hidden turbulence in the painter’s depiction of the sky.

“The scale of the paint strokes played a crucial role,” author Yongxiang Huang said. “With a high-resolution digital picture, we were able to measure precisely the typical size of the brushstrokes and compare these to the scales expected from turbulence theories.”

To reveal hidden turbulence, the authors used brushstrokes in the painting like leaves swirling in a funnel of wind to examine the shape, energy, and scaling of atmospheric characteristics of the otherwise invisible atmosphere. They used the relative brightness, or luminance, of the varying paint colors as a stand-in for the kinetic energy of physical movement.

“It reveals a deep and intuitive understanding of natural phenomena,” Huang said. “Van Gogh’s precise representation of turbulence might be from studying the movement of clouds and the atmosphere or an innate sense of how to capture the dynamism of the sky.”

Their study examined the spatial scale of the painting’s 14 main whirling shapes to find out if they align with the cascading energy theory that describes the kinetic energy transfer from large- to small-scale turbulent flows in the atmosphere.

They discovered the overall picture aligns with Kolmogorov’s law, which predicts atmospheric movement and scale according to measured inertial energy. Drilling down to the microcosm within the paint strokes themselves, where relative brightness is diffused throughout the canvas, the researchers discovered an alignment with Batchelor’s scaling, which describes energy laws in small-scale, passive scalar turbulence following atmospheric movement.

Finding both scalings in one atmospheric system is rare, and it was a big driver for their research.

“Turbulence is believed to be one of the intrinsic properties of high Reynolds flows dominated by inertia, but recently, turbulence-like phenomena have been reported for different types of flow systems at a wide range of spatial scales, with low Reynolds numbers where viscosity is more dominant,” Huang said.

“It seems it is time to propose a new definition of turbulence to embrace more situations.”

Matthew Rozsa provides a more accessible description of the research in a September 20, 2024 article for Salon.com, Note: Links have been removed,

… one can look at “The Starry Night” and see a scientifically accurate representation of turbulent, cascading waters — a visual that may have directly inspired van Gogh before he transposed those dynamics into his iconic starry sky while painting in his mental asylum room in the French town of Saint-Rémy-de-Provence.

“Imagine you are standing on a bridge, and you watch the river flow. You will see swirls on the surface, and these swirls are not random.” Yongxiang Huang, lead author of the study, told CNN. “They arrange themselves in specific patterns, and these kinds of patterns can be predicted by physical laws.”

Scientists fascinated by van Gogh’s art are not limited to physicists. When researchers discovered a gecko that reminded them of the paintings of van Gogh, they gave it the scientific name Cnemaspis vangoghi. As a common terms, the authors suggested “van Gogh’s starry dwarf gecko.”

Here’s a link to and a citation for the paper,

Hidden turbulence in van Gogh’s The Starry Night by Yinxiang Ma (马寅翔), Wanting Cheng (程婉婷), Shidi Huang (黄仕迪), François G. Schmitt, Xin Lin (林昕), Yongxiang Huang (黄永祥). Physics of Fluids Volume 36, Issue 9 September 2024 DOI: https://doi.org/10.1063/5.0213627

This article is behind a paywall.

The physics of Jackson Pollock’s painting technique

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I long ago stumbled across the fascination that Jackson Pollock’s art work exerts over physicists but this work from Brown University adds some colours to the picture (wordplay intended).

One: Number 31, 1950. Jackson Pollock (American, 1912–1956). 1950. Oil and enamel paint on canvas, 8′ 10″ x 17′ 5 5/8″ (269.5 x 530.8 cm) Courtesy: Museum of Modern Art (MOMA) [downloaded from: https://www.moma.org/learn/moma_learning/jackson-pollock-one-number-31-1950-1950/]

From an October 30, 2019 Brown University news release (also on EurekAlert),

The celebrated painter Jackson Pollock created his most iconic works not with a brush, but by pouring paint onto the canvas from above, weaving sinuous filaments of color into abstract masterpieces. A team of researchers analyzing the physics of Pollock’s technique has shown that the artist had a keen understanding of a classic phenomenon in fluid dynamics — whether he was aware of it or not.

In a paper published in the journal PLOS ONE, the researchers show that Pollock’s technique seems to intentionally avoid what’s known as coiling instability — the tendency of a viscous fluid to form curls and coils when poured on a surface.

“Like most painters, Jackson Pollock went through a long process of experimentation in order to perfect his technique,” said Roberto Zenit, a professor in Brown’s School of Engineering and senior author on the paper. “What we were trying to do with this research is figure out what conclusions Pollock reached in order to execute his paintings the way he wanted. Our main finding in this paper was that Pollock’s movements and the properties of his paints were such he avoided this coiling instability.”

Pollock’s technique typically involved pouring paint straight from a can or along a stick onto a canvas lying horizontally on the floor. It’s often referred to as the “drip technique,” but that’s a bit of a misnomer in the parlance of fluid mechanics, Zenit says. In fluid mechanics, “dripping” would be dispensing the fluid in a way that makes discrete droplets on the canvas. Pollock largely avoided droplets, in favor of unbroken filaments of paint stretching across the canvas.

In order to understand exactly how the technique worked, Zenit and colleagues from the Universidad Nacional Autonoma de Mexico analyzed extensive video of Pollock at work, taking careful measure of how fast he moved and how far from the canvas he poured his paints. Having gathered data on how Pollock worked, the researchers used an experimental setup to recreate his technique. Using the setup, the researchers could deposit paint using a syringe mounted at varying heights onto a canvas moving at varying speeds. The experiments helped to zero in on the most important aspects of what Pollock was doing.

“We can vary one thing at a time so we can decipher the key elements of the technique,” Zenit said. “For example, we could vary the height from which the paint is poured and keep the speed constant to see how that changes things.”

The researchers found that the combination of Pollock’s hand speed, the distance he maintained from the canvas and the viscosity of his paint seem to be aimed at avoiding coiling instability. Anyone who’s ever poured a viscous fluid — perhaps some honey on toast — has likely seen some coiling instability. When a small amount of a viscous fluid is poured, it tends to stack up like a coil of rope before oozing across the surface.

In the context of Pollock’s technique, the instability can result in paint filaments making pigtail-like curls when poured from the can. Some prior research had concluded that that the curved lines in Pollock’s paintings were a result of this instability, but this latest research shows the opposite.

“What we found is that he moved his hand at a sufficiently high speed and a sufficiently short height such that this coiling would not occur,” Zenit said.

Zenit says the findings could be useful in authenticating Pollock’s works. Too many tight curls might suggest that a drip-style painting is not a Pollock. The work could also inform other settings in which viscous fluids are stretched into filaments, such as the manufacture of fiber optics. But Zenit says his main interest in the work is that it’s simply a fascinating way to explore interesting questions in fluid mechanics.

“I consider myself to be a fluid mechanics messenger,” he said. “This is my excuse to talk science. It’s fascinating to see that painters are really fluid mechanicians, even though they may not know it.”

Here’s a link to and a citation for the paper,

Pollock avoided hydrodynamic instabilities to paint with his dripping technique by Bernardo Palacios, Alfonso Rosario, Monica M. Wilhelmus, Sandra Zetina, Roberto Zenit. PLOS ONE DOI: https://doi.org/10.1371/journal.pone.0223706 Published: October 30, 2019

This paper is open access.

I could not find any videos related to this research that I know how to embed but Palacios, Zetina, and Zenit have investigated Polock’s ‘physics’ before,

If you want to see Pollock dripping his painting in action, there’s a 10 min. 13 secs. film made in 1950 (Note: Links have been removed from text; link to 10 min. film is below),

In the summer of 1950, Hans Namuth approached Jackson Pollock and asked the abstract expressionist painter if he could photograph him in his studio, working with his “drip” technique of painting. When Namuth arrived, he found:

“A dripping wet canvas covered the entire floor. Blinding shafts of sunlight hit the wet canvas, making its surface hard to see. There was complete silence…. Pollock looked at the painting. Then unexpectedly, he picked up can and paintbrush and started to move around the canvas. It was as if he suddenly realized the painting was not finished. His movements, slow at first, gradually became faster and more dancelike as he flung black, white and rust-colored paint onto the canvas.”

The images from this shoot “helped transform Pollock from a talented, cranky loner into the first media-driven superstar of American contemporary art, the jeans-clad, chain-smoking poster boy of abstract expressionism,” one critic later wrote in The Washington Post.

You can find the film and accompanying Open Culture text intact with links here.

Ooblek (non-Newtonian goo) and bras from Reebok

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I have taken a liberty in the title for this piece, strictly speaking the non-Newtonian goo in the bra isn’t the stuff (ooblek) made of cornstarch and water from your childhood science experiments but it has many of the same qualities. The material in the Reebok bra, PureMove, is called Shear Thickening Fluid and was developed at the University of Delaware in 2005 and subsequently employed by NASA (US National Aeronautics and Space Administration) for use in the suits used by astronauts as noted in an August 6, 2018 article by Elizabeth Secgran for Fast Company who explains how it came be used for the latest sports bra,

While the activewear industry floods the market with hundreds of different sports bras every season, research shows that most female consumers are unsatisfied with their sports bra options, and 1 in 5 women avoid exercise altogether because they don’t have a sports bra that fits them properly.

Reebok wants to make that experience a thing of the past. Today, it launches a new bra, the PureMove, that adapts to your movements, tightening up when you’re moving fast and relaxing when you’re not. …

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When I visited Reebok’s Boston headquarters, Witek [Danielle Witek, Reebok designer who spearheaded the R&D making the bra possible] handed me a jar of the fluid with a stick in it. When I moved the stick quickly, it seemed to turn into a solid, and when I moved it slowly, it had the texture of honey. Witek and the scientists have incorporated this fluid into a fabric that Reebok dubs “Motion Sense Technology.” The fluid is woven into the textile, so that on the surface, it looks and feels like the synthetic material you might find in any sports bra. But what you can’t see is that the fabric adapts to the body’s shape, the velocity of the breast tissue in motion, and the type and force of movement. It stretches less with high-impact movements and then stretches more during rest and lower intensity activities.

I tested an early version of the PureMove bra a few months ago, before it had even gone into production. I did a high-intensity workout that involved doing jumping jacks and sprints, followed by a cool-down session. The best thing about the bra was that I didn’t notice it at all. I didn’t feel stifled when I was just strolling around the gym, and I didn’t feel like I was unsupported when I was running around. Ultimately, the best bras are the ones that you don’t have to think about so you can focus on getting on with your life.

Since this technology is so new, Reebok had to do a lot of testing to make sure the bra would actually do what it advertised. The company set up a breast biomechanics testing center with the help of the University of Delaware, with 54 separate motion sensors tracking and measuring various parts of a tester’s chest area. This is a far more rigorous approach than most testing facilities in the industry that typically only use between two to four sensors. Over the course of a year, the facility gathered the data required for the scientists and Reebok product designers to develop the PureMove bra.

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… If it’s well-received, the logical next step would be to incorporate the Motion Sense Technology into other products, like running tights or swimsuits, since transitioning between compression and looseness is something that we want in all of our sportswear. ..

According to the Reebok PureMove bra webpage, it was available from August 16, 2018,

Credit: Reebok

It’s $60 (I imagine those are US dollars).

For anyone interested in the science of non-Newtonian goo, shear thickening fluid, and NASA, there’s a November 24, 2015 article by Lydia Chain for Popular Science (Note: Links have been removed),

There’s an experiment you may have done in high school: When you mix cornstarch with water—a concoction colloquially called oobleck—and give it a stir, it acts like a liquid. But scrape it quickly or hit it hard, and it stiffens up into a solid. If you set the right pace, you can even run on top of a pool of the stuff. This phenomenon is called shear force thickening, and scientists have been trying to understand how it happens for decades.

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There are two main theories, and figuring out which is right could affect the way we make things like cement, body armor, concussion preventing helmets, and even spacesuits.

The prevailing theory is that it’s all about the fluid dynamics (the nature of how fluids move) of the liquid and the particles in a solution. As the particles are pushed closer and closer together, it becomes harder to squeeze the liquid out from between them. Eventually, it’s too hard to squeeze out any more fluid and the particles lock up into hydrodynamic clusters, still separated by a thin film of fluid. They then move together, thickening the mixture and forming a solid.

The other idea is that contact forces like friction keep the particles locked together. Under this theory, when force is applied, the particles actually touch. The shearing force and friction keep them pressed together, which makes the solution more solid.

“The debate has been raging, and we’ve been wracking our brains to think of a method to conclusively go one way or the other,” says Itai Cohen, a physicist at Cornell University. He and his team recently ran a new experiment that seems to point to friction as the driving cause of shear thickening.

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Norman Wagner, a chemical engineer at the University of Delaware, says that research into frictional interactions like this is important, but notes that he isn’t completely convinced as Cohen’s team didn’t measure friction directly (they inferred it was friction from their modeling however they didn’t find the exact measurement of the friction between the particles). He also says that there’s a lot of data in the field already that strongly indicates hydrodynamic clusters as the cause for shear thickening.

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Wagner and his team are working on a NASA funded project to improve space suits so that micrometeorites or other debris can’t puncture them. They have also bent their technology to make padding for helmets and shin guards that would do a better job protecting athletes from harmful impacts. They are even making puncture resistant gloves that would give healthcare workers the same dexterity as current ones but with extra protection against accidental needle sticks.

“It’s a very exciting area,” says Wagner. He’s very interested in designing materials that automatically protect someone, without robotics or power. …

I guess that in 2015 Wagner didn’t realize his work would also end up in a 2018 sports bra.

Jackson Pollock’s physics

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Take a mathematician (L. Mahadevan), a physicist (Andrzej Herczynski), and an art historian (Claude Cernuschi) and you’re liable to get a different perspective on Jackson Pollock*, a major figure in abstract expressionism, art. (I’m pretty sure there’s a joke in there of the: “There was mathematician and a physicist in a bar when an art historian came in …” ilk. I just can’t come up with it. If you can, please do leave it in the comments.)

Let’s start with a picture (image downloaded from the Wikipedia essay about Jackson Pollock’s No. 5, 1948),

No. 5, 1948 (Jackson Pollock, downloaded from Wikipedia essay about No. 5, 1948)

In a recent paper published in Physics Today (Painting with drops, jets, and sheets, which is behind a paywall), Mahadevan, Herczynski, and Cernuschi speculate about Pollock’s intuitive understanding of physics, in this case, fluid dynamics. From the June 28, 2011 news item on physorg.com,

A quantitative analysis of Pollock’s streams, drips, and coils, by Harvard mathematician L. Mahadevan and collaborators at Boston College, reveals, however, that the artist had to be slow—he had to be deliberate—to exploit fluid dynamics in the way that he did.

The finding, published in Physics Today, represents a rare collision between mathematics, physics, and art history, providing new insight into the artist’s method and techniques—as well as his appreciation for the beauty of natural phenomena.

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“My own interest,” says Mahadevan, “is in the tension between the medium—the dynamics of the fluid, and the way it is applied (written, brushed, poured…)—and the message. While the latter will eventually transcend the former, the medium can be sometimes limiting and sometimes liberating.”

Pollock’s signature style involved laying a canvas on the floor and pouring paint onto it in continuous, curving streams. Rather than pouring straight from the can, he applied paint from a stick or a trowel, waving his hand back and forth above the canvas and adjusting the height and angle of the trowel to make the stream of paint wider or thinner.

Simultaneously restricted and inspired by the laws of nature, Pollock took on the role of experimentalist, ceding a certain amount of control to physics in order to create new aesthetic effects.

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The artist, of course, must have discovered the effects he could create through experimentation with various motions and types of paint, and perhaps some intuition and luck. But that, says Mahadevan, is the essence of science: “We are all students of nature, and so was Pollock. Often, artists and artisans are far ahead, as they push boundaries in ways that are quite similar to, and yet different from, how scientists and engineers do the same.”

There’s more about this study on the physorg.com site including a video illustrating fluid dynamics. You can also find a June 29, 2011 news item on Science Daily and a June 29, 2011 article in Harvard Magazine about the study. From the Harvard news article,

MODERN ART WAS NEVER more famously lampooned than when Tom Stoppard [playwright and screenwriter] said, “Skill without imagination is craftsmanship and gives us many useful objects such as wickerwork picnic baskets. Imagination without skill gives us modern art.”

The article by expanding on Mahadevan’s research gives the lie to Stoppard’s quote. (I wonder if Stoppard will write a play about physics and art in the light of this new thinking about Pollock’s work?)

This all brought to mind, Richard Jackson’s work which was featured in 2010 at the Rennie Collection in Vancouver (my most substantive comments about Jackson’s work are in my May 11, 2010 posting). Trained as both an artist and an engineer, he too works with paint and its vicosity. I still remember the piece in the gallery basement that featured three (as I recall) cans of paint apparently caught in the act of being poured. In retrospect, one of the things I liked best about the show is that a lot of Jackson’s work is very much about the physical act of painting and the physicality of the materials.

One final note, the L. in Mahadevan’s name stands for Lakshinarayan.

*’Pollock’s’ corrected to Pollock on April 27, 2017.