The deep-sea sponge Euplectella aspergillum, additionally referred to as Venus’s flower basket is well known for its intricate glass skeleton. The sponge’s body is covered in pores, through which water is constantly drawn into and out of its central body cavity to filter food particles and exchange gases. This shape gives fantastic mechanical aid and has influenced a slew of robust, lightweight bridges and skyscrapers.
The skeleton of E. aspergillum consists of a typical square frame that is diagonally fortified and forms the scaffolding for the sponge’s hollow cylindrical body. In addition, extrinsic corrugations spiral around the main body and are superimposed on the frame. To dissect the effect of each skeletal component on the fluid flows, Falcucci and colleagues generated several idealized models of the sponge for observation. These models included a plain solid cylinder, a hollow cylindrical lattice, a solid cylinder with helical rims, and a hollow cylindrical lattice with helical rims.
Ascertaining the fluid flows for these different models required hyper-accurate fluid-dynamics simulations. These can concurrently conclude a level of detail from the microscopic flows around the skeleton up to the bulk flows around the entire organism. To make these in silico procedures viable, Falcucci et al. numerically solved the equations that dictate such flows using a method that fits in with parallel computing on GPUs.
It is properly chronicled that, in water flows of 1–10 cm/s or more, solid cylinders approximating to the size of E. aspergillum go through vortex shedding — a procedure in which repeating patterns of twirling maelstroms form on the postliminary side of an object. This phenomenon results in voluminous velocity variations in the wake of the cylinder and fluctuating and elevated hydrodynamic drag. Falcucci et al.’s in silico experimentation showed that a hollow cylindrical frame acts as a permeable object that curbs such velocity variations and curtails drag. Given that hydrodynamic forces can be powerful enough to dislocate a sea sponge, reduced drag improves the organism’s durability in the presence of strong flows.
These in-silico examinations have greatly advanced knowledge about fluid flow through E. aspergillum, but there is still much that is not understood. For example, Falcucci et al. were able to show that the sponge’s external helical ridges prolong the inhabitancy of particles in the central cavity but failed to quantify how this helps the organism absorb food particles and exchange gases.
A New Horizon in Fluid Dynamics
This work provides a striking example of how modern numerical simulations can be used to explore problems in areas such as biomechanics, bioinspired design, and fundamental fluid dynamics. Falcucci et al.’s results propose that many of the convoluted structures seen in marine invertebrates and other organisms have unpredictable ramifications for fluid dynamics. Such multiscale flow simulations may be used to understand the hydrodynamics of gas exchange via coral reefs or the aerodynamics of pollen capture.
Moreover, this study of Venus’s flower basket divulges how convoluted designs can influence fluid flow for numerous functions, including drag decrement, mechanical support, and particle filtering. The lessons learnt from this organism could inspire augmented multifaceted engineering structures, such as sampling and filtering devices.