Unraveling Krill's Metachronal Symphony and Hydrodynamic Secrets

This research aims to investigate the causal flow dynamics associated with the metachronal swimming mode used by krill, along with its correlation to the force generation exhibited by these fascinating creatures. Krill, which possess five legs distributed along their body, propel themselves by coordinating the movement of their legs and body. Our study seeks to comprehend the synchronized paddling motion of these legs and its role in generating two primary types of hydrodynamic forces: kinematic forces resulting from the inertia of the flow and vortex-induced forces originating from vorticity produced by the legs. We will closely examine how the specific kinematic parameters of metachronal swimming influence the contribution of these two forces. Additionally, we will show the impact of the coordinated opening and closure of the interior legs during metachronal swimming in enhancing wake dynamics and better hydrodynamic force generation. Employing a combined immersed body method-boundary element method approach for simulations and flow analysis, the study uses a reciprocal theorem to unify various force partitioning methods and demonstrate its effectiveness in analyzing force contributions.