Swarm of slender pusher and puller swimmers at finite Reynolds numbers

The study of the flow field resulting from suspensions of swimmers at moderate Reynolds numbers, along with hydrodynamic interactions, has received little attention until now despite being of great interest to researchers in the fields of marine ecology, biology, and engineering. By means of direct numerical simulations, employing a state-of-the-art fully resolved immersed boundary method, the suspensions of inertial slender pusher and puller swimmers are investigated in dilute volume fractions and swimming Reynolds numbers ranging from 1 to 50 with the objective to identify the existence of correlated flow motions and scales when inertia plays a crucial role. The properties of the flow field resulting from the collective motion of the swimmers, as well as the characteristics of their orientation along with their temporal correlation, have been analyzed. Results show nontrivial flow motions as the Reynolds number changes along with a complex swimmer dynamics.