Structural Co-inhabitation Theory (SCT): A Complementary Framework to Navier-Stokes for Aerial Locomotion in Turbulent Fields This preprint introduces Structural Co-inhabitation Theory (SCT), a structural framework describing the relationship between locomoting systems and turbulent fluid fields — a layer of description that Navier-Stokes equations, by design, do not address. SCT derives three indices from standard fluid-dynamic parameters: the Turbulent Coexistence Index (TCI), phase cost (κ'), and stabilization density (ρ). Together these define a structural spin index Φ characterizing both the magnitude and directional orientation of a system's structural position relative to a theoretical gauge state of complete co-inhabitation. The framework is applied to three aerial systems — wandering albatross, golden eagle, and Boeing 737 NG — demonstrating that structurally distinct biological and engineered implementations converge on comparable Φ magnitudes through opposite structural orientations. This work is independent research with no institutional affiliation or external funding. Formal peer review submission is planned. Related updates may be available at: patreon.com/NMStructuralTheoryLab
Yugo Matsumoto (Sun,) studied this question.