E. aspergillum, also known as Venus’s flower basket due to its vase-like shape, is a fascinating deep-sea glass sponge that is of great interest to the research community for various reasons. Its glassy skeleton, for instance, is arranged in a unique lattice-like structure that, because of its high strength-to-weight ratio, can pave the way to provide stronger and, at the same time, lighter structures for the construction of buildings and bridges. In addition, its optical properties captivate fiber optics researchers: the natural glass fibers produced by the sponge have less optical loss and are mechanically more flexible than the ones we fabricate. However, little is known about how fluid flows around and through E. aspergillum: while this information can shed more light on its intricate behavior and potential applications, such a study requires elaborate multiscale simulations that are computationally expensive to be executed. Giacomo Falcucci and colleagues take on this task by making use of massive computing facilities to perform state-of-the-art numerical simulations, studying the fluid-dynamic performance of the sponge in its actual living conditions.
The simulations were performed using the lattice Boltzmann method, a scalable and versatile approach that mimics the dynamic behavior of fluid flows without directly solving the equations of continuum fluid mechanics. Different values of water speed and multiple simulation scales (from microscopic geometric details to the entire organism) were considered, and given the complexity of the biological model, their study required an impressive amount of resources. The authors used two different supercomputing facilities (one of them being one of the most powerful supercomputers in the world), using more than two million hours of processing time. The simulation results showed in detail how the organism’s cylindrical lattice suppresses velocity fluctuations and decreases drag, thus improving robustness when in the presence of strong flows. The study also suggests that there is a substantial reduction of the flow speed inside the body cavity thanks to helical ridges in its structure, which likely aids in the sponge’s selective filter feeding and in the encounter between gametes for efficient reproduction. Overall, the results not only improve our understanding of Venus’s flower basket, but can also be used to improve our engineering structures in the future (for instance, drag reduction and efficient particle filtering). As deep-sea organisms are often inaccessible to in vivo experimentation, this is also a remarkable achievement for the computational science community, and a clear example of how numerical simulations and in silico experiments can move a field of study forward.
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Chirigati, F. Fluid dynamic behavior of deep-sea sponges. Nat Comput Sci 1, 504 (2021). https://doi.org/10.1038/s43588-021-00120-0