An efficient medium-fidelity model of anguilliform locomotion: insights into collective swimming efficiency and deformation dynamics

We propose a reduced-order model for the inviscid flow past self-propelled flexi- ble bodies whose geometry features a wedged trailing-edge. The model leverages an unsteady panel method and its compact representation of vorticity in the free flow allows for computationally tractable simulations. It is strongly coupled to a multi-body system solver which computes the internal bending moments in a swimming system of deforming bodies. The model is assessed against commer- cial computational fluid dynamics and vortex-method predictions on the specific case of anguilliform locomotion. The verified tool is subsequently leveraged in a campaign of numerical experiments to shed light on the collective benefits drawn from swimming in formation. We find that fish initially at rest and engaged in collective swimming demonstrate superior cost efficiency during the initial phases of their motion. However, beyond a certain temporal threshold, these piscine cohorts begin to expend more energy per unit of distance traversed in comparison to their solitary counterparts.