STIMULATION OF BIOLUMINESCENCE BY TURBULENT PIPE-FLOW

The response of in situ luminous marine organisms is studied over a wide range of flow agitation associated with laminar and turbulent pipe flow. Because a fully developed pipe flow is hydrodynamically well characterized, it is particularly suited for studying bioluminescence stimulation. Results show a dramatic increase in bioluminescent activity when transition occurs from laminar to turbulent flow. Above transition, as the flow rate (and turbulence) increases, an accompanying rise in bioluminescence is observed that results primarily from more organisms being stimulated. The hydrodynamic parameters for the 6.35 mm diameter pipe, where significant bioluminescent stimulation began, are: wall shear stress = 22-27 dyn cm-2, wall strain rate = 1915-2350s-1, and an average shear stress throughout the pipe of 11-13.5 dyn cm-2. The smallest turbulent length scale at bioluminescent onset is on the order of 33 μm. © 1990.