Award: OCE-1260232

Laminar flow into a pipe, a very basic problem in fluid flow, was widely regarded to have been solved in the late 1800s. The classic solution appears in nearly every engineering hydraulics text. The proposal for this grant pointed out that a boundary condition assumed in that solution, i.e., uniform velocity across the entire pipe opening, cannot be correct. What the flow rates and patterns are just outside, at, and just inside a pipe entrance are central to engineered flows as well as to many aquatic organisms that feed on suspended material in the oceans and fresh waters. Active suspension feeding by pumping water into a tube-like structure is common among bivalves, ascidians, bryozoans, polychaete worms, and burrowing and tube-dwelling crustaceans. Flow rates and patterns into these structures determine not only where the food comes from but also delineate the region from which the animals can obtain chemical sensory information and determine the costs of pumping. A three-part approach integrated engineering analysis and experiments with biological oceanographic applications to expedite a replacement solution?s progress from fluid engineering research and applications to biological applications. Engineers at the University of Colorado and biological oceanographers at the University of Maine jointly applied finite-element modeling approaches to inhalant laminar flows. The engineers used the models to design and evaluate inanimate laboratory model systems to test the numerical model?s predictions and provide a replacement for the current descriptions of pipe entry in engineering texts. The biological oceanographers in turn used both the models and the engineering results to optimize flow measurements of inhalant flows produced by bivalves and tunicates. Results allow applications such as the determination of the spacing between bivalves at which their feeding volumes begin to interact. A central result is that flows outside the siphon are more unidirectional, paralleling the pipe flow at lower Reynolds numbers, and tending toward omnidirectional convergence at higher Reynolds numbers. Anticipated applications include microfluidics, design of water-sampling devices, and assessment of carrying capacity of waters for bivalve aquaculture. Last Modified: 06/02/2017 Submitted by: Peter A Jumars