Complex Emergent Dynamics in Fish Schools - Insights from a Flow-Physics-Informed Model of Collective Swimming in Fish

Complex collective behavior emerges in fish schools due to a combination of behavioral imperatives (such as safety from predators, improved foraging, etc.) propulsive forces, and the hydrodynamic forces induced by the complex flow field encountered by fish swimming in a school. Hydrodynamics also plays a key role in enabling a fish to sense the position/velocity of neighbors and to control its own velocity and heading. Finally, hydrodynamic interactions can be exploited by fish in schools to improve swimming performance. In the current study, we employ a new model of collective swimming of fish that has three key features: (a) the model is based on the balance of forces and moments on the fish; (b) the model includes interaction with the vortex wakes of fish; (c) the model is parametrized via data from direct numerical simulations (DNS) of a swimming fish. The model is used to examine emergent topologies and dynamical behavior of fish schools, as well as the effect of key parameters on swimming efficiency, and visual and lateral line sensing in fish schools.