For instance, it has been shown that mean lift ranges from 2.63 N at 100 m to 0.76 N at 4000 m. Numerical results indicate a strong correlation between the intensity of forces exerted on the wing and the flight altitude. In an attempt to reproduce the variations in the thermophysical parameters of air vs altitude, subroutines have been implemented in a finite-volume-based code. We sought to assess this hypothesis using a numerical model of the wing flapping kinematics of a migratory bird and an evaluation of the cyclic variation of aerodynamic forces as a function of altitude (100 to 4000 m). Numerous studies suggest that increased frequency would be an adaptive mechanism of flapping flight in hypodense and hypobaric air. Migratory birds have developed remarkable physiological and biomechanical adaptive capacities in order to fly at very high altitudes and benefit from favorable wind.
