Mandal Joy, Sarkar Sandip
SERB Sponsored Microfluidics Laboratory, Department of Mechanical Engineering, Jadavpur University, Kolkata 700032, India.
Langmuir. 2024 Aug 20;40(33):17489-17499. doi: 10.1021/acs.langmuir.4c01680. Epub 2024 Aug 5.
Despite extensive research on droplet dynamics at microfluidic T-junction, for different droplet lengths and Capillary numbers, there remains limited understanding of their dynamics at different viscosity ratio. In this study, we adopt a modeling framework in a three-dimensional (3D) configuration to numerically investigate the droplet dynamics as it passes through a symmetric T-junction with varying Capillary numbers, droplet lengths, and viscosity ratios. We present a 3D regime map for the first time to demarcate the droplet breakup and no breakup regimes. Herein, we propose a simple surface equation accounting for the critical Capillary number for breakup, in terms of viscosity ratio and dimensionless droplet length. The proposed universal relationship aligns well with experimental and computational findings from the existing literature. Furthermore, we reveal a new droplet breakup characteristic at high viscosity ratio and high Capillary number where the droplet spreads almost twice its initial value before splitting. Overall, this research provides comprehensive understanding of droplet dynamics at the T-junction and has significant implications for several related applications, including the large-scale synthesis of microdroplets using microchannel networks.
尽管对微流体T型结处的液滴动力学进行了广泛研究，但对于不同的液滴长度和毛细管数，人们对它们在不同粘度比下的动力学仍了解有限。在本研究中，我们采用三维（3D）构型的建模框架，对液滴通过具有不同毛细管数、液滴长度和粘度比的对称T型结时的动力学进行数值研究。我们首次给出了一个3D状态图，以划分液滴破碎和不破碎状态。在此，我们根据粘度比和无量纲液滴长度，提出了一个简单的表面方程来解释破碎的临界毛细管数。所提出的通用关系与现有文献中的实验和计算结果吻合良好。此外，我们还揭示了在高粘度比和高毛细管数下的一种新的液滴破碎特性，即液滴在分裂前几乎扩展到其初始值的两倍。总体而言，本研究全面理解了T型结处的液滴动力学，对包括使用微通道网络大规模合成微滴在内的多个相关应用具有重要意义。
