Researchers in Japan have studied how artists like Akiko Nakayama take advantage of fluid mechanics to create their art.
Japanese artist Akiko Nakayama manipulates alcohol and inks to create tree-like dendritic patterns … [+]
Akiko Nakayama creates dynamic art live on stage. She calls her method Alive Painting, and it consists of close-up photographs of different liquids and other materials interacting. One of the techniques he uses is to pour ink mixed with alcohol onto a layer of paint, which immediately spreads creating unique fractal shapes. Nakayama knows what she's doing, but she still doesn't have full control over everything that happens on the surface. The art forms itself, and now researchers have studied it more closely to learn more about the physics behind the art.
“Painters have often used fluid mechanics to create unique compositions,” said Eliot Fried at the Okinawa Institute of Science and Technology (OIST). “We've seen it with David Alfaro Siqueiros, Jackson Pollock and Naoko Tosa, just to name a few.”
Fried heads the Mechanics and Materials Unit at OIST and is one of the researchers who studied Nakayama's art, along with physicist Chan San To. “In our lab we reproduce and study artistic techniques, to understand how the characteristics of the fluids influence the final result,” says Fried.
Chan has been studying the fractal formation of acrylic paint for a few years. In 2021, the American Physical Association shared a video of Chan and colleagues demonstrating that alcohol and a diluted paint base coat are necessary for the ink to form fractals.
But what is the physics behind this phenomenon? In a research paper published in PNAS Nexus earlier this year, Chan and Fried explore different factors that affect how paint spreads. One of them is the Marangoni effect, and it describes the tendency of the fluid to move towards areas of higher surface tension. It's the same effect that creates “legs” in a wine glass when you swirl or tilt the glass, but in this case it's pulling the ink towards the edge of the ink bubble and into the thinned paint layer.
Researchers now have a better understanding of how this dendritic art is formed.
But why would the ink form fractal shapes and not slowly diffuse into the paint below? The researchers also found an answer to this question: it has to do with the viscosity of the underlying paint layer. This viscosity must change when the liquid is disturbed, like ketchup that becomes easier to pour when you shake the bottle.
“In dendritic painting, the expanding drop of ink cuts through the underlying layer of acrylic paint. It's not as strong as shaking a ketchup bottle, but it's still a form of shear stress,” says Chan. “Like ketchup, the more stress there is, the easier it is for the ink droplets to flow.”
By experimenting with the paint layer using different dilutions or different amounts of paint, it is possible to have some control over the eventual fractal pattern created by the ink droplets, although much of the final pattern is still left to chance because each dendritic paint be unique .
Understanding how dendritic paint works could have other applications or reveal insights useful for other fluid mechanics applications, but Chan and Fried only pursued this project because they are interested in the scientific processes behind the art.
“Why should we limit science only to technological progress?” Chan asks. “I also like to explore its potential to drive artistic innovation.”
