Extended Data Fig. 9: Noise attenuation by trailing edge serrations.
From: Adaptations for stealth in the wing-like flippers of a large ichthyosaur
a, b, Vortex structures visualized using the Lambda2 method for flipper geometries (a) without and (b) with trailing edge serrations at 0° α. c, d, Details of a virtual model featuring chordwise ridges and trailing edge serrations (c, leading edge; d, trailing edge). e–g, Average velocity fluctuations observed across a serration-equipped hydrofoil at (e) 0, (f) 5 and (g) 10° α, respectively. h, Comparison of SPL 250 m upstream of flipper geometries with (solid lines) and without (dashed lines) trailing edge serrations at five α (0, 5, 10, 15, and 20°). i, Comparison of SPL at three locations (5, 50 and 250 m) upstream of flipper geometries with (solid lines) and without (dashed lines) trailing edge serrations at 0° α. Data were collected for 67.5 convection times. Spectra in h and i are based on 65,536 wide Hanning windows, 50% overlap and 33 samples.
