自润湿液滴与液层相互作用中的聚结与颈缩断裂过程研究
Investigation of coalescence and pinch-off processes of a self-rewetting drop interacting with a liquid layer
AI总结：
本研究采用轴对称相场格子玻尔兹曼方法，模拟非均匀加热下自润湿液滴与液层相互作用，发现自润湿流体比普通流体更早发生颈缩断裂，且增大M2或Q可缩短断裂时间并扩大断裂区域。
摘要：
自润湿流体（SRFs），如长链含水醇类，是一类特殊的液体，其表面张力对温度的依赖呈反常的二次方关系，导致其热毛细流动与普通流体（NFs）显著不同。本研究聚焦于非均匀加热条件下自润湿液滴与液层相互作用的行为。为此，我们采用一种基于中心矩的稳健格子玻尔兹曼方法，并结合轴对称公式表达的相场模型，以高效捕捉三维效应。我们研究了自润湿流体中的聚结与颈缩断裂过程，并与普通流体进行了对比。模拟结果表明，自润湿流体比普通流体更早发生颈缩断裂。我们还观察到，增加奥内佐格数Oh会抑制颈缩断裂过程，凸显了粘性力的相对作用，该作用受重力效应或邦德数Bo的调节。此外，我们探讨了表面张力对温度的无量纲线性与二次敏感系数M1和M2，以及无量纲热流Q的变化如何影响聚结/颈缩断裂行为。有趣的是，与普通流体中的行为相反，在自润湿流体中，增加M2或Q会缩短颈缩断裂所需的时间，并扩大Oh-Bo状态图中发生颈缩断裂的区域，与未加热情况相比。这些差异被证明是由于界面上的热毛细力变化所致。总体而言，我们发现，在非均匀加热条件下，自润湿流体在更广泛的条件下比普通流体更能促进颈缩断裂过程。
英文摘要：
Self-rewetting fluids (SRFs), such as long-chain aqueous alcohols, are a special class of liquids with surface tension that is anomalously dependent quadratically on temperature, resulting in thermocapillary flows that differ significantly from those in normal fluids (NFs). This study focuses on investigating the behavior of SRF drops interacting with a liquid layer under nonuniform heating conditions. In this regard, we employ a robust central moment-based lattice Boltzmann method with a phase-field model expressed in an axisymmetric formulation to capture three-dimensional effects efficiently. We investigate the coalescence and pinch-off processes in SRFs and compare them to those in NFs. Our simulations reveal that SRFs undergo pinch-off earlier than NFs. We also observe that increasing the Ohnesorge number Oh suppresses the pinch-off process, highlighting the relative role of viscous forces, which is modulated by gravity effects or the Bond number Bo. Furthermore, we explore how varying the dimensionless linear and quadratic sensitivity coefficients of surface tension on temperature, M1 and M2, respectively, and the dimensionless heat flux Q influence the coalescence/pinch-off behavior. Interestingly, contrary to the behavior in NFs, in SRFs increasing M2, or Q reduces the time required to pinch-off and widens the region in the Oh-Bo regime map where pinch-off occurs, when compared to the unheated cases. These differences are shown to be due to the variations in the thermocapillary forces on the interface. Overall, we find that under nonuniform heating, the SRFs enhance the pinch-off process compared to NFs across a wider range of conditions.
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