Abstract

We study unsteady internal flows in a sessile droplet of capillary size evaporating in constant contact line mode on a heated substrate. Three-dimensional simulations of internal flows in evaporating droplets of ethanol and silicone oil have been carried out. For describing the Marangoni flows we find it necessary to account for the diffusion of vapor in air, the thermal conduction in all three phases and thermal radiation. The equations have been solved numerically by finite element method using ANSYS Fluent. As a result of the simulations, the nonstationary behavior of Bénard-Marangoni (BM) instabilities is obtained. At the first stage, a flower structure of BM cells near the triple line emerge. For smaller contact angles, the cells grow in size and occupy the central region of the droplet surface. Being closely connected with recent experimental and theoretical studies, the results obtained help to analyze and resolve the associated issues.

中文翻译：

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在加热的基底上干燥挥发性液滴中的不稳定Bénard-Marangoni不稳定性建模

摘要

我们研究了在恒定的接触线模式下在加热的基底上蒸发的毛细管大小的无蒂液滴中的非稳态内部流动。进行了乙醇和硅油蒸发液滴内部流动的三维模拟。为了描述Marangoni流动，我们发现有必要考虑空气中蒸汽的扩散，所有三相的热传导和热辐射。使用ANSYS Fluent通过有限元方法对方程进行了数值求解。作为仿真的结果，获得了Bénard-Marangoni（BM）不稳定性的非平稳行为。在第一阶段，在三重系附近出现了BM细胞的花结构。对于较小的接触角，细胞的尺寸会增大并占据液滴表面的中心区域。