Stability and energetics of schooling fish: insights from direct numerical simulations

Since the early 1970's it has been hypothesized that fish gain considerable hydrodynamic benefits by swimming in schools. Studies have shown that schooling fish can, in certain formations, obtain higher swimming efficiencies compared to their isolated counterparts. However, many of the beneficial formations predicted by studies may be unstable and fish may have to expend additional energy in order to maintain their position within the group. Thus, schooling formations may arise from a compromise between energy savings and stability. In the current study, we employ 3D direct numerical simulations (DNS) coupled with body-dynamics to explore the stability and energetics of freely-swimming fish in various schooling formations. The model allows for multiple degrees-of-freedom in the motion of the fish and the simulations provide insights into the stability of various schooling formations.