Pumping by oscillating plates viscous to inertial transitions in metachronal arrays

January 3 – Febuary 28, 2021

Meeting Abstract

S10-5  Thu Jan 7 14:00 – 14:30  Pumping by oscillating plates: viscous to inertial transitions in metachronal arrays Kiger, KT; University of Maryland kkiger@umd.edu

External transport and locomotion within biological systems has long recognized that there exists a natural divide between systems dominated by viscous flow and that dominated by inertia. In simple single or paired appendages, this typically takes the form of a either a rowing type of kinematics for viscous low Reynolds numbers conditions (Re << 1), with the forces generated in the direction of the stroke, whereas for inertially dominated high Reynolds number conditions (Re >> 1) a flapping type motion produces forces perpendicular to the stroke motion. Inherently, the transition is enabled by a symmetry breaking condition provided by the nonlinear nature of inertially dominated flows. In the viscous dominated flows, the asymmetry must be introduced by the kinematics explicitly, and in metachronal systems this can be introduced by the phasing of the adjacent appendages, as well as by temporal asymmetries in the power and recovery stroke of individual plates, and physical asymmetries due to conformal transformations of the appendage itself. In this work, we examine transitions inspired by the study of mayfly nymphs, which exhibit all of the above effects, as well as looking at similar related systems across different animal systems. This is done first through the study of a representative animal system (Centroptilum triangulifer), followed by mechanical and numerical simulations across a broader range of simplification and conditions to better understand how these transitions are enabled and benefit they might provide.

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