Effect of Heave Amplitude on the Propulsive Performance of Tandem Flapping Foils

Abstract

The current study investigates the flow dynamics around rigid flapping NACA0015 foils in tandem configuration at low Reynolds number. The effect of the heave amplitude of the upstream foil on the propulsive performance of the downstream foil is studied for heave amplitudes of 0.2-1 times the downstream foil chord length. The tandem foils are modelled as rigid foils with prescribed sinusoidal motion and the flow is formulated numerically by variational stabilized Petrov-Galerkin finite element technique with the help of moving mesh arbitrary Lagrangian-Eulerian framework. The heave amplitude of the upstream foil is found to have significant impact on the propulsion of the downstream foil. The trend of the propulsive performance can be explained by the type of vortex interaction, which may be favourable or unfavourable for thrust generation.