Applied Math Lab, Courant Institute, New York University, New York, New York 10012, USA.
Physics Department, New York University, New York, New York 10003, USA.
Phys Rev Lett. 2021 Mar 19;126(11):114501. doi: 10.1103/PhysRevLett.126.114501.
We demonstrate flow rectification, valveless pumping, or alternating to direct current (AC-to-DC) conversion in macroscale fluidic networks with loops. Inspired by the unique anatomy of bird lungs and the phenomenon of directed airflow throughout the respiration cycle, we hypothesize, test, and validate that multiloop networks exhibit persistent circulation or DC flows when subject to oscillatory or AC forcing at high Reynolds numbers. Experiments reveal that disproportionately stronger circulation is generated for higher frequencies and amplitudes of the imposed oscillations, and this nonlinear response is corroborated by numerical simulations. Visualizations show that flow separation and vortex shedding at network junctions serve the valving function of directing current with appropriate timing in the oscillation cycle. These findings suggest strategies for controlling inertial flows through network topology and junction connectivity.
我们展示了在具有环路的宏观流体网络中实现了流动整流、无阀泵送或交流电（AC-to-DC）转换。受鸟类肺部独特解剖结构和呼吸循环中定向气流现象的启发，我们假设、测试和验证了多环网络在高雷诺数下受到振荡或交流激励时会表现出持续循环或直流流动。实验表明，对于施加振荡的更高频率和幅度，会产生不成比例的更强循环，并且这种非线性响应得到了数值模拟的证实。可视化显示，网络连接处的流动分离和涡旋脱落起到了在振荡周期中适时引导电流的阀的作用。这些发现为通过网络拓扑和节点连接控制惯性流提供了策略。
