CFD study of biologically inspired flapping/oscillating foils in forward motion
by
Joel Guerrero
University of Genova

Nature relies on reciprocating motions for locomotion and propulsion on land, in the air and the sea; legs for walking, flapping wings for flying and oscillating fins for swimming. These refined and optimized forms and motions used by nature, may serve engineers and scientists as an inspiration model, with the hope of finding a way to provide better and greater propulsive efficiencies and manoeuvrability than propellers and rotors at low Reynolds numbers in human built vehicles, such as; MAVs (micro aerial vehicles) and AUVs (autonomous underwater vehicles). The fluid dynamics of many swimming and flying animals involves the generation and shedding of vortices into the wake. In the present paper, we use an overlapping grids based incompressible flow solver to numerically study the unsteady dynamics of these vortices shed by two-dimensional flapping/oscillating foils that models an animal wing, fin or tail in forward motion. The study is done for several shapes and harmonic and non-harmonic kinematics, at a corresponding Reynolds number of the order of 1000 (such values are relevant for typical swimming and flying animals). Some numerical aspects of the overlapping grids method and preliminary three-dimensional results are also presented.

Date received: March 11, 2008