The hydrodynamics of ribbon-fin propulsion during impulsive motion.

摘要: Weakly electric fish are extraordinarily maneuverable swimmers, able to swim as easily forward backward and rapidly switch direction, among other maneuvers. The primary propulsor of gymnotid is an elongated ribbon-like anal fin. To understand the mechanical basis their maneuverability, we examine hydrodynamics a non-translating ribbon fin in stationary water using computational fluid dynamics digital particle image velocimetry (DPIV) flow fields around robotic Computed forces compared with drag measurements from towing cast thrust estimates for measured swim-direction reversals. We idealize movement traveling sinusoidal wave, derive scaling relationships how varies wavelength, frequency, amplitude wave height. compare these prior theoretical work. mechanism production generation streamwise central jet associated attached vortex rings. Under certain regimes, also generates heave force, which pushes body up body-fixed frame. In one such regime, show that number waves along decreases approximately two-thirds, force surpasses surge force. This undulatory parallel oscillatory normal may be important understanding orientation median fins vary length them. Our results will useful neural control weakly knifefish well engineering bio-inspired vehicles thrusters.