Figure 2.

Experimental trajectories and computationally calculated velocities in horizontal (XY) plane beside horizontal and vertical shear stresses on the flap surface. a) Trajectories of particles visualized in four snapshots of the oscillatory cycle taken with an exposure time of 2 ms. Scale bar 5 mm. b) A snapshot of flow velocities from CFD simulations (see also Movie S4, Supporting Information). CFD analysis of shear stress tangential to the flap's curved surface in horizontal and vertical directions on the c) backside and d) frontside, respectively. The left sides of the rectangles are in contact with the dish wall and the right sides are pointing towards the center of dish (see also Movies S5–S8, Supporting Information).