The work is inspired by the mayfly nymph, which is an aquatic insect that uses array of 7 external plate pairs to pump fresh oxygenated water over its body, allowing it to enhance its respiration in regions of locally reduced oxygen concentration. The interesting aspect of the mayfly is that as it grows through its life-cycle, it moves from a regime where the pumping is dominated by viscous frictional forces to one where it is dominated by inertia. Traditionally, flows have been studied at the extreme ends of these operating conditions, and study of this model will allow us to improve how we design efficient micropumps for sensor or micro-reactor applications.
The objective of the proposed work is to map out the role of various kinematics (motion of the gill plates) on the efficiency of the mass transport to the surface of the appendages. This will allow us to answer questions such as, How can one optimally pump a fluid stream to maximally sample it? We will use a combination of experimental measurement conducted on a scaled robotic oscillating plate array, as well as advanced Fluid-Solid Interaction Direct Numerical Simulation (FSI-DNS) to study the problem across a range of parametric space relevant to both mayflies and many micro-chemical sensors.
Intellectual Merit: Two fundamental fluid mechanics problems will be addressed by asking (1) What mechanisms can an array of oscillating elements effectively maximize either the volume flowrate of a pumped current or the species mass flux to the array surface, as the array transitions between a viscous-dominated and an inertia-dominated regime? 2) How is the performance of an oscillating appendage pump (or more generally any flapping locomotor) affected by structural flexibility and the coupled response dictated by the fluid-structure interaction?
Broader Impact: The successful completion of the proposed work will provide computational tools, design constraints and guidelines for producing a pumped current with a oscillating array of plates with a minimal amount of energy expenditure. These tools and observations will be of direct benefit to applications of pumping in micro-systems, such autonomous chemical sensors of micro lab-on-achip chemical analysis devices, and indirect benefit to other flapping systems such as micro-aerial vehicles or miniature aquatic robots.
