Abstract: The bio-inspired aerial–aquatic vehicle off ers attractive perspectives for future intelligent robotic systems. Cormorant’s 
webbed-feet support water-surface takeoff is a typical locomotion pattern of amphibious water birds, but its highly maneuverable and agile kinetic behaviors are inconvenient to measure directly and challenging to calculate convergently. This paper 
presents a numerical Computational Fluid Dynamic (CFD) technique to simulate and reproduce the cormorant's surface 
takeoff process by modeling the three-dimensional biomimetic cormorant. Quantitative numerical analysis of the fl uid fl ows 
and hydrodynamic forces around a cormorant’s webbed feet, body, and wings are conducted, which are consistent with 
experimental results and theoretical verifi cation. The results show that the webbed feet indeed produced a large majority of 
the takeoff power during the initial takeoff stage. Prior lift and greater angle of attack are generated to bring the body off the 
water as soon as possible. With the discussion of the mechanism of the cormorant’s water-surface takeoff and the relevant 
characteristics of biology, the impetus and attitude adjustment strategies of the aerial–aquatic vehicle in the takeoff process 
are illustrated.

Key words: Aerial–aquatic vehicle, Cormorant’s takeoff, Quantitative hydrodynamic analysis, Computational Fluid Dynamics (CFD), Multiphase flow, Bionic prototype verifi cation