Meeting Abstract
To investigate the interaction between flow and coral morphology, laboratory measurements of boundary layer hydrodynamics were obtained over 3-D printed artificial models of Scleractinian corals using a recirculating water flume. Measurements were collected using particle image velocimetry (PIV), and two-dimensional velocity fields were calculated upstream, above, and downstream of four idealized coral models. The models represented a range of surface rugosity values, from a smooth hemisphere to a highly convoluted natural coral skeleton, and flow conditions ranged from 2.5 – 15 cm/s. Estimates of Reynolds stress, turbulent kinetic energy (TKE), and vorticity were derived from the velocity measurements, and conditional analyses determined the degree of anisotropy in the flow. Results found that coral surface rugosity delays flow separation on the downstream edge of the models, allowing for a greater surface area to be exposed to turbulent mixing and mass exchange processes. Larger rugosity values also enhanced TKE values directly above and downstream of the corals, which enhanced rates of turbulent production and dissipation. The measurements suggest that increased rugosity in coral morphology can accelerate turbulent eddy formation and enhance scalar mass mixing. Increases in turbulent mixing, along with greater surface area contact with the turbulent boundary layer, should serve to promote nutrient and dissolved chemical flux at the coral-water interface and benefit coral health.
