A non‐reciprocal architected porous medium

Abstract

In several fluid flow, energy-dumping, and energy-harvesting applications, a dominant flow direction or dominant resistance direction is desirable. In this study, we propose a simple modular geometry that doubles flow resistance in one direction relative to the opposite direction, while maintaining laminar viscous flow. We analyze planar two-component Particle Image Velocimetry results to investigate flow characteristics in the two opposing principal flow directions and to evaluate the relationship between the flow patterns and the observed macroscopic flow resistances. It was observed that, in a manner similar to observations in other asymmetric incompressible viscous flows, inertial phenomena contribute to the breaking of reciprocity. Some geometrical variations are also explored, providing an overview of the importance of different flow features in determining flow resistance. Low flow resistance is observed in continuous-flow streams, whereas high flow resistance is associated with jet production and dissipation. Ideally, these two situations correspond to the favorable and unfavorable flow directions, respectively, resulting in a large pressure drop difference between them, as observed in some of the tested geometries. We have also observed, in the higher-velocity studies, the emergence of a symmetry-breaking flow structure that gives rise to a new flow pattern with alternating jet deflections.