NSF Award
2410986
Numerous small organisms that swim, fly, smell, or feed in flows at scales in which inertial and viscous forces are nearly balanced rely on using branched, bristled, and hairy body structures. Such structures have significant biological implications. In coral, they determine the success rate of catching prey through particle capture, and there are many other organisms which similarly rely on the transition of their body structures from solid surfaces to leaky/porous “rakes.” Active particles (e.g. swimming plankton and microorganisms) can also enhance or reduce capture through their own behaviors. Although flows around such organisms have been studied before, the fluid dynamic mechanisms underlying the leaky-rake to solid-plate transition and how it affects particle capture remain unclear. The goal of this project is the development of open-source numerical software to elucidate the fluid dynamics of such biological and bioinspired filtering arrays, including how the individual and collective behavior of the active particles affects filtering outcomes. In addition, the Investigators will design software training materials and complementary classroom modules. The Investigators will engage in public outreach for all ages through targeted modalities for different age demographics such as participating in the Skype A Scientist program for younger children and coral reef conservation courses aimed at older retirees which will incorporate math and physics.<br/><br/>The natural world is replete with mesoscale filters that are significant to biological and biomedical applications. These are, however, challenging multiscale problems that require high accuracy to resolve the flow through complex structures that are sensitive to small perturbations. To understand these problems, the research team aims to 1) develop a Method of Regularized Oseenlets that can be employed as a gridless method to resolve flows through filtering structures for Reynolds numbers near unity, 2) develop and test force spreading operators that are independent of the grid size for the immersed boundary method, 3) develop and implement numerical techniques to efficiently describe the interactions of agents in flow with moving, complex 3D boundaries, and 4) implement tools from sensitivity analysis and uncertainty quantification to reveal which parameters are important for particle capture and to guide the development of more detailed agent and flow models. Upon doing so, the project will focus on the filter feeding of plankton by Cnidarians and will address the following (i) identifying small-scale flow patterns within rigid and flexible filtering structures at the leaky-to-solid transition, (ii) understanding how small-scale flow patterns affect the capture of Brownian swimmers, and (iii) determining the collective effect of fundamental behaviors in small organisms for capture and targeting in the presence of flow. The frameworks developed here can be broadly applied to other biological systems where mesoscale exchange occurs, e.g. the filtering structures of fish or the chemical sensors of insects and crabs.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
