Soltys, Michael听1听;听Crimaldi, John P听2
1听University of Colorado
2听University of Colorado
Turbulent fluid flow plays an important role in many physical and biological mixing processes. 听This is exemplified by broadcast spawning, the reproductive strategy used by corals and many other marine invertebrates. 听When spawning, male and female invertebrates release their gametes into a flow and then rely on the physics of turbulence to bring eggs and sperm close enough to promote fertilization. 听Current biological models predict that the efficiency of broadcast spawning is vastly insufficient to sustain coral populations (Denny, 1988), but the existence of these animals suggests otherwise. 听It is likely that the role of instantaneous turbulent stirring, missing from current models, is responsible for the under-prediction of spawning efficiency. 听In order for broadcast spawning to be successful it is necessary that the sperm and the eggs be brought together in high concentrations. 听It has been shown that over short time scales structured filaments of high concentration form in turbulent flow before being dispersed to low concentrations at longer times (Crimaldi and Koseff, 2006). 听It is hypothesized that when two scalars (e.g., sperm and eggs) are released into turbulent flow, coherent velocity structures will initially bring high-concentration filaments of these two scalars together. 听This Hypothesis is听studied听using a specially developed two-channel planar laser-induced听fluorescence听system which tracks two dyes as听surrogates听for coral sperm and egg. 听Preliminary results confirm the importance of coherent structures and their effects on mixing.