Flow interaction of three-dimensional self-propelled flexible plates in tandem

Tandem configurations of two self-propelled flexible flappers finite span are explored by means numerical simulations. The same sinusoidal vertical motion is imposed on the leading edge both flappers, but with a phase shift ( $\phi$ ). In addition, offset, $H$ , prescribed between flappers. that emerge characterized in terms their hydrodynamic performance and topology. reach stable configuration constant mean propulsive speed equilibrium horizontal distance. Depending different tandem observed, namely compact regular configurations. upstream flapper (i.e. leader) virtually equal to an isolated flapper, except configuration, where close interaction downstream follower) results higher power requirements than flapper. Conversely, follower's significantly affected wake leader analysis flow shows influenced jet induced vortex rings shed leader. This can be beneficial or detrimental for performance, depending alignment velocity motion. Finally, qualitative prediction hypothetical follower presented. model semi-empirical, it uses field