Effect of aspect ratio on the propulsive performance of tandem flapping foils

In this work, we describe the impact of aspect ratio ( $AR$ ) on performance optimally phased, identical flapping flippers in a tandem configuration. Three-dimensional simulations are performed for seven sets single and finite foils at moderate Reynolds number, with thrust producing, heave-to-pitch coupled kinematics. Increasing slenderness (or is found to improve coefficients augmentation but benefits level off towards higher values . However, propulsive efficiency shows no significant change increasing , while hind foil outperforms by small margin. Further analysis spanwise development propagation vortical structures allows us gain some insights into mechanisms these wake interactions provide valuable information design novel biomimetic propulsion systems.