Figure 5
From: An inertial mechanism behind dynamic station holding by fish swinging in a vortex street
Phase-averaged trajectory of an individual fish in the space of cross-stream/streamwise accelerations in different swimming modes: blue—regular swimming outside the wake in the uniform flow field, red—swinging in the wake, green—swimming regimes which can not be uniquely identified. The non-averaged trajectory in the swinging regime is shown by the pale red line. Observe the well-defined figure of eight in swinging mode, when the fish ’pushes off’ the cross-stream flow to produce positive streamwise acceleration. The figure shows phase trajectory of fish #1 recorded for 22 s. The foil oscillation frequency is 2 Hz.
