The effects of wing twist in slow-speed flapping flight of birds: trading brute force against efficiency

Abstract

Effective angle of attack geo Geometric angle of attack in Inflow angle Circulation around the spanwise axis Kinematic viscosity Fluid density Angular velocity of the wing z Vorticity around the spanwise axis 2D Two-dimensional 3D Three-dimensional A Peak-to-peak amplitude of the wing AR Aspect ratio b Wing span c Chord length D Drag D ind Induced drag d 0 Drag at zero degrees angle of attack DOF Degree of freedom DPIV Digital particle image velocimetry DPSS Diode pumped solide state