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At the bottom of the Pacific Ocean, cylindrical clumps of the glass sponge Euplectella aspergillum protrude like skyscrapers in the deep sea. some house tiny shrimpAccording to whom, an 11-inch sponge is actually high-rise. And the sponge’s glass skeleton is definitely an architectural feat, consisting of a geometric lattice that gives the sponge the impression of being wrapped in lace. Yet it is enduringly tough, able to take root on the seafloor and in air currents without breaking or splintering.
Such structural superpowers leave many scientists eager to unravel the secrets contained in this crystal sponge. The answers can solve engineering problems like how to design a tall building that won’t collapse in strong winds. A study published Wednesday Journal of the Royal Society Interface reveals how protrusions in the sponge’s skeleton suppress a devastating phenomenon called eddy shedding, which can cause catastrophic damage to structures such as chimneys and chimneys.
“These studies support the idea that the fluid dynamic properties of glass sponges may be no less remarkable than their structural properties,” said Giacomo Falcucci, a mechanical engineer at the University of Rome Tor Vergata and not involved in the research. email.
Beneath the soft tissue of the glass sponge, a tubular skeleton protects and supports the animal. The core skeleton consists of bundles of needed forms, called spicules, oriented vertically, horizontally, and diagonally and fused together in a lattice structure somewhat resembling a checkerboard. Surrounding this cage are clockwise and counterclockwise spiral protrusions, resembling a series of fire escapes that wrap around the tubular sponge and underneath its tissue. All together, the ridges look like a maze.
“It’s a very dense, highly consolidated system,” said James Weaver, a senior scientist in Harvard University’s school of engineering and applied sciences and author of the new paper. The study was also led by researchers Katia Bertoldi and Matheus Fernandes from the same school.
Dr. Weaver began studying Euplectella aspergillum in the early 2000s. He first focused on sponge skeletons, investigating their various structures and mechanical properties.
For this article, the researchers examined the sponge from a hydrodynamic perspective: how fluids move and act on its skeleton.
They pursued this problem after noticing that the ridges of sponges bear an uncanny resemblance to ridge-like protrusions, spiral rows, often used to maintain the structural integrity of towers and other cylinders. When a fluid, such as air, moves around a flat cylinder, eddies alternately scatter from side to side on the downwind side of the cylinder. These alternating eddies can cause the cylinder to vibrate, causing noise and safety concerns. In human architecture, spiral rows suppress the eddies, disrupting the flow around the structure.
To understand whether the outer protrusions of the glass sponge provide a similar hydrodynamic benefit, the researchers built a series of mechanical and computational models to visualize how the sponge’s anatomy affects the flow of surrounding fluids.
Their model showed that the sponge’s dorsal labyrinth completely eliminated eddy shedding. “What we found in the sponge structure is that it can suppress it completely instead of just delaying it or reducing it,” said Mr. Fernandes. An obvious application of the new research would be to design sponge-inspired spiral rows.
The authors hypothesize that this highly complex skeleton helps fix the sponge in the soft sediments of the seafloor that could be excavated by the swirling eddies. Dr. “The sponge can be supported,” Weaver said.
“This sponge skeleton fascinates materials scientists,” wrote Sally Leys, an invertebrate zoologist at the University of Alberta who was not involved in the research. “However – one big thing – they always neglect the animal’s tissues.”
Unlike past research that only looked at the sponge’s skeleton, the new paper includes several models that attempt to reconstruct the soft, porous texture of a living sponge.
Dr. In Leys’ eyes, some new paper models that flow through a porous sponge are unrealistic. Dr. “Water doesn’t move passively through a glass sponge,” Leys said. “They control the flow.”
Dr. Leys explained that ocean sponges use an internal pump to channel water into nanometer-sized openings where food and oxygen are exchanged and waste is expelled, and then the water exits through other pores and eventually leaves the top of the sponge.
Dr. Leys also found the amount of flow the researchers chose to simulate around the sponge “wildly realistic” because it was much larger than the peak flow a living Euplectella could experience, Leys said.
The researchers acknowledged that not all of their models were designed to reflect a sponge living in the wild. Instead, they simulated high flow levels to demonstrate the potential utility of the sponge structure for engineering.
Dr. Leys worries that the models may be misleading. “The actual biology of these exotic animals needs much more consideration by materials scientists,” he said.
While the vortex-suppressing properties of living glass sponges remain a mystery, the researchers’ results illuminate the use of the endoskeleton as a surrogate for man-made structures.
“It is important to understand the power of being inspired by nature,” said Mr. Fernandes.
In such a future, our terrestrial chimneys may begin to look more like a bustling shrimp metropolis in the deep sea.
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