Um Eujin, Kim Minjun, Kim Hyoungsoo, Kang Joo H, Stone Howard A, Jeong Joonwoo
Department of Physics, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 44919, Republic of Korea.
Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
Nat Commun. 2020 Oct 15;11(1):5221. doi: 10.1038/s41467-020-18930-7.
Hydrodynamic interactions play a role in synchronized motions of coupled oscillators in fluids, and understanding the mechanism will facilitate development of applications in fluid mechanics. For example, synchronization phenomenon in two-phase flow will benefit the design of future microfluidic devices, allowing spatiotemporal control of microdroplet generation without additional integration of control elements. In this work, utilizing a characteristic oscillation of adjacent interfaces between two immiscible fluids in a microfluidic platform, we discover that the system can act as a coupled oscillator, notably showing spontaneous in-phase synchronization of droplet breakup. With this observation of in-phase synchronization, the coupled droplet generator exhibits a complete set of modes of coupled oscillators, including out-of-phase synchronization and nonsynchronous modes. We present a theoretical model to elucidate how a negative feedback mechanism, tied to the distance between the interfaces, induces the in-phase synchronization. We also identify the criterion for the transition from in-phase to out-of-phase oscillations.
流体动力学相互作用在流体中耦合振荡器的同步运动中发挥作用，理解其机制将有助于流体力学应用的发展。例如，两相流中的同步现象将有利于未来微流控装置的设计，无需额外集成控制元件即可实现微滴生成的时空控制。在这项工作中，利用微流控平台中两种不混溶流体相邻界面的特征振荡，我们发现该系统可以作为一个耦合振荡器，显著表现出液滴破裂的自发同相同步。通过对同相同步的这一观察，耦合液滴发生器展现出耦合振荡器的一整套模式，包括异相同步和非同步模式。我们提出了一个理论模型来阐明与界面之间距离相关的负反馈机制如何诱导同相同步。我们还确定了从同相振荡到异相振荡转变的判据。
