Active fluid mixing generated by a robotic coral

Xeniid corals are unique among animals as they exhibit active motion for purposes other than locomotion. The corals use their tentacles to pulse the surrounding fluid, removing oxygen waste and enhancing the photosynthetic rate of their symbiotic algae. To understand the fluid dynamics involved, we developed a robotic coral that mimics the pulsing motion of the corals. We imaged the active flows generated by the robot and collected 3D particle tracking velocimetry (PTV) using a novel high-speed two-color scanning volumetric laser-induced fluorescence (H2C-SVLIF) imaging technique. We present flow visualizations and quantify the mixing metrics of the coral in intermediate Reynolds number regime.