Modeling flying formations as flow-mediated matter

Fuente: arXiv
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Autori principali: Mavroyiakoumou, Christiana, Wu, Jiajie, Ristroph, Leif
Natura: Preprint
Pubblicazione: 2025
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author Mavroyiakoumou, Christiana
Wu, Jiajie
Ristroph, Leif
author_facet Mavroyiakoumou, Christiana
Wu, Jiajie
Ristroph, Leif
contents Collective locomotion of swimming and flying animals is fascinating in terms of individual-level fluid mechanics and group-level structure and dynamics. Here we bridge and relate these scales through a model of formation flight that views the collective as a material whose properties arise from the flow-mediated interactions among its members. We build on and revise an aerodynamic model describing how flapping flyers produce vortex wakes and how they are forced by others' wakes. While simplistic, the model faithfully reproduces a series of physical experiments carried out over the last decade on pairwise interactions of flapping foils. By studying longer in-line arrays, we show that the group behaves as a soft "crystal" with regularly spaced member "atoms" whose positioning is, however, susceptible to deformations and dynamical instabilities. Poking or wiggling a member excites longitudinal waves (flow-mediated phonons, or "flonons") that pass down the group while growing in amplitude, and indeed the internal excitation from flapping is sufficient to trigger instabilities. Linear analysis of the model explains the aerodynamic origin of the lattice spacing, the springiness of the "bonds" between flyers, and the tendency for disturbances to resonantly amplify. Other properties such as the timescales for instability growth and wave propagation seem to involve the full nonlinear behavior. These findings suggest intriguing analogies with physical materials that could be generally useful for understanding and analyzing animal groups. Several properties displayed by our system seem particularly relevant to biological collectives, namely group cohesion and organization, sensitive detection of and response to perturbations, and transmission of information through traveling waves.
format Preprint
id arxiv_https___arxiv_org_abs_2506_14025
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Modeling flying formations as flow-mediated matter
Mavroyiakoumou, Christiana
Wu, Jiajie
Ristroph, Leif
Fluid Dynamics
Biological Physics
Collective locomotion of swimming and flying animals is fascinating in terms of individual-level fluid mechanics and group-level structure and dynamics. Here we bridge and relate these scales through a model of formation flight that views the collective as a material whose properties arise from the flow-mediated interactions among its members. We build on and revise an aerodynamic model describing how flapping flyers produce vortex wakes and how they are forced by others' wakes. While simplistic, the model faithfully reproduces a series of physical experiments carried out over the last decade on pairwise interactions of flapping foils. By studying longer in-line arrays, we show that the group behaves as a soft "crystal" with regularly spaced member "atoms" whose positioning is, however, susceptible to deformations and dynamical instabilities. Poking or wiggling a member excites longitudinal waves (flow-mediated phonons, or "flonons") that pass down the group while growing in amplitude, and indeed the internal excitation from flapping is sufficient to trigger instabilities. Linear analysis of the model explains the aerodynamic origin of the lattice spacing, the springiness of the "bonds" between flyers, and the tendency for disturbances to resonantly amplify. Other properties such as the timescales for instability growth and wave propagation seem to involve the full nonlinear behavior. These findings suggest intriguing analogies with physical materials that could be generally useful for understanding and analyzing animal groups. Several properties displayed by our system seem particularly relevant to biological collectives, namely group cohesion and organization, sensitive detection of and response to perturbations, and transmission of information through traveling waves.
title Modeling flying formations as flow-mediated matter
topic Fluid Dynamics
Biological Physics
url https://arxiv.org/abs/2506.14025