Glass sponges reveal important properties for the design of ships, skyscrapers and planes of the future

The remarkable structural properties of the Venus Flower Basket Sponge (E. aspergillum) may appear remote from human-designed structures. However, information on how the organism’s network of holes and ridges influences the hydrodynamics of nearby seawater could lead to advanced designs for buildings, bridges, marine vehicles, and airplanes. , and anything that must respond safely to the forces imposed by air flow or water.

While previous research has studied the structure of the sponge, there have been few studies on the hydrodynamic fields surrounding and penetrating the organism, and whether, in addition to improving its mechanical properties, the skeletal patterns of E. Aspergillum underpin the optimization of the physics of flow into and beyond its body cavity.

A collaboration on three continents at the frontiers of physics, biology and engineering led by Giacomo Falcucci (from Tor Vergata University in Rome and Harvard University), in collaboration with Sauro Succi (Italian Institute of Technology ) and Maurizio Porfiri (Tandon School of Engineering, New York University) applied super computational muscle and special software to better understand these interactions, creating a very first simulation of the deep sea sponge and how it reacts and influence the flow of water nearby.

The book “Extreme flow simulations Reveal skeletal adaptations of deep-sea sponges”, published in the journal Nature, revealed a deep connection between the structure and function of the sponge, highlighting both the basket sponge’s ability to withstand the dynamic forces of the surrounding ocean and its ability to create a vortex rich in nutrients in the body cavity “basket”.

“This organism has been studied a lot from a mechanical point of view because of its amazing ability to deform considerably despite its fragile and crystalline structure,” said first author Giacomo Falcucci of the University of Tor Vergata in Rome and the ‘Harvard University. “We were able to study aspects of hydrodynamics to understand how the geometry of the sponge provides a functional response to the fluid, to produce something special regarding the interaction with water.”

“By exploring the flow of fluid in and out of the sponge’s body cavity, we uncovered the imprints of an expected adaptation to the environment. Not only does the sponge’s structure contribute to reduce drag, but it also facilitates the creation of low-speed vortices in the body cavity that are used for feeding and reproduction, ”added Porfiri, co-author of the study.

The structure of E. Aspergillum, reproduced by co-author Pierluigi Fanelli, of the University of Tuscia, Italy, resembles a delicate glass vase in the form of a thin-walled cylindrical tube with a large central atrium, siliceous spicules – thus their commonly used name, “glass sponges”. The spicules are composed of three perpendicular rays, giving them six points. The microscopic spicules “weave” together to form a very fine mesh, which gives the body of the sponge a rigidity not found in other species of sponges and allows it to survive at great depths in the sea. the water column.

To understand how the Venus Flower Basket sponges achieve this, the team made extensive use of the exascale Marconi100 class computer from CINECA’s high performance computing center in Italy, which is capable of creating full simulations using billion three-dimensional dynamic and temporo-spatial data points. .

The researchers also used special software developed by study co-author Giorgio Amati, of SCAI (Super Computing Applications and Innovation) at CINECA, Italy. The software enabled super computer simulations based on Lattice Boltzmann’s methods, a class of computational fluid dynamics methods for complex systems that represent the fluid as a set of particles and track the behavior of each one.

The in-silico experiments, featuring approximately 100 billion virtual particles, reproduced the hydrodynamic conditions of the deep seabed where E. Aspergillum lives. The results processed by Vesselin K. Krastev at Tor Vergata University in Rome allowed the team to explore how the organization of holes and ridges in the sponge improves its ability to reduce the forces applied by water. moving sea (a mechanical engineering question formulated by Falcucci and Succi), and how its structure affects the dynamics of flow in the body cavity of the sponge to optimize selective filter feeding and gamete encounter for the sexual reproduction (a biological question formulated by Porfiri and an expert biologist on ecological adaptations in aquatic creatures, co-author Giovanni Polverino of the Center for Evolutionary Biology at the University of Western Australia, Perth).

“This work is an exemplary application of discrete fluid dynamics in general and the Lattice Boltzmann method in particular,” said co-author Sauro Succi of the Italian Institute of Technology and Harvard University. Sauro Succi is internationally recognized as one of the fathers of the Lattice Boltzmann method. “The precision of the method, combined with access to one of the best supercomputers in the world, allowed us to perform levels of computation never attempted before, which shed light on the role of fluid flows in the process. adaptation of living organisms in the abyss. ”

“Our investigation of the role of sponge geometry on its response to fluid flow has many implications for the design of high-rise buildings or, really, any mechanical structure, from skyscrapers to new structures. low drag for ships, or aircraft fuselages, “Falcucci said.” For example, will there be less aerodynamic drag on tall buildings constructed with a similar lattice of ridges and holes? Will this optimize the distribution of applied forces? Answering these same questions is a key objective of the team.