Wave-current interactions over coral reef morphology

The exchange of nutrients and dissolved gasses between corals and the surrounding water, which in part dictates how effectively a coral can function, relies on sufficient turbulence-driven mixing. However, the interaction between waves and turbulence is not fully understood when the bottom boundary consists of rough and spatially inhomogeneous surfaces such as coral heads. We employ particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) concurrently in a wave-current laboratory flume to measure velocities and scalar concentrations. 3D-printed, scaled-down coral heads create complex roughness features on the bed of the flume. This allows us to calculate mean quantities such as vertical flux, bottom drag, and energy dissipation, as well as determine phase dependance through phase averaging. More broadly, our results can help with developing models for predicting drag and fluxes over coral reefs.