Three-dimensional numerical simulation of a bird model in unsteady flight

In this paper, a type of numerical simulation of a three-dimensional (3D) bionic bird with flapping wings in a viscous flow is studied. The model is a self-propelled flying bird capable of free rotation and translation whose flying motion follows the laws of conservation of momentum and angular momentum. The bird is propelled and lifted through flapping and rotating wings and most of thrust force and lift force are exerted on both wings. Both the vortex structures and the flight characteristics are also presented. The relationship between both wings' movement and the vortex structures as well as that between both wings' movement and flight characteristics are also analyzed in this paper. The study uses a 3D computational fluid dynamics package that includes the combined immersed boundary method, volume of fluid method, adaptive multigrid finite volume method, and control strategy for swimming and flying.