Christiana Mavroyiakoumou

Modelling flying formations with state-dependent delays

Collective locomotion of flying animals is fascinating in terms of individual-level fluid mechanics and group-level structure and dynamics. In this talk, I will introduce a model of formation flight that views the collective as a material whose properties arise from the flow-mediated interactions among its members. It builds on an aerodynamic model that describes how flapping flyers produce vortex wakes and how they are influenced by the wakes of others. Long in-line arrays show that the group behaves as a soft “crystal” with regularly ordered member “atoms” whose positioning is susceptible to deformations and dynamical instabilities. Perturbing a member produces longitudinal waves that pass down the group while growing in amplitude; with these amplifications even causing collisions. The model explains the aerodynamic origin of the spacing between the flyers, the springiness of the interactions, and the tendency for disturbances to resonantly amplify. I will also talk about how neighbour spacing and phase relationships influence both stability and energetic cost, revealing “goldilocks zones” where formation flight is simultaneously stable and energetically efficient. Our findings show how aerodynamic interactions and stability constraints shape collective flight strategies and suggest broader connections between animal groups and material systems.