Flow Physics and Vortex-Induced Acoustics in Bio-Inspired Collective Locomotion

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Schooling phenomenon is ubiquitous in nature. Its prominent examples include swarms of fish, flight of birds in specific formations, and collective locomotion of small-scale biological objects, such as sperms. Such configurations help the members significantly reduce the energetic cost of propulsion as well as enhance their thrust and efficiency. In these natural dynamical systems, highly unsteady three-dimensional vortices emerge due to undulatory kinematics of each member of the school. It becomes more complex due to the interaction of coherent structures with the bodies moving in their vicinity. Furthermore, these activities generate pressure disturbances in the surrounding fluid, causing the spread of acoustic signals in water. This preamble provides the foundation of my plan to build and grow my research career in the fields of computational fluid-structure-acoustic interaction (FSAI) and bio-inspired robotics, which supports my long-term research objective of developing next-generation high-speed, efficient, and stealth nature-inspired robots. The presently proposed research focusses on the development of a novel computational solver through the sharp-interface immersed-boundary method to handle intense fluid-structure interactions, involving multiple oscillating bodies. Moreover, this solver facilitates the extraction and analysis of coherent flow structures to identify their roles for producing unsteady forces. The methodology will substantially contribute towards developing accurate theoretical and computational models of different natural swimmers and their schooling configurations. It is also particularly relevant to understand the mechanisms adopted by fish to communicate through pressure signals in surrounding flows, which allows them to feel the presence of other moving objects and acts as a tool for navigation. For this purpose, I will develop modules to compute acoustic signatures in the numerical solver to understand how vortex-body interactions impact the emission of pressure disturbances in flow fields.  This work is important to establish principles for designing autonomous fish-like robots capable of swimming silently without causing disruptions in natural habitats. Besides bio-inspired robots and energy harvesters, applications of the fundamental knowledge gained through this research and novel computational tools developed in this program are cross-disciplinary. These include the examination of various FSAI-related biological mechanisms, dynamics of different bodies in environmental flows, and the acoustic emissions in the environment from engineered systems. Along with training HQPs in multidisciplinary areas, this project will also address the development of educational modules on fluid dynamics for students in high school physics and introduce various outreach activities for young women and indigenous people to inspire them about STEM.