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Multi-scale approach to model steady meniscus evaporation in a wetting fluid
Physical Review Fluids ( IF 2.7 ) Pub Date : 
Kishan Bellur, Ezequiel F. Médici, Chang Kyoung Choi, James C. Hermanson, and Jeffrey S. Allen

Evaporation along a curved liquid vapor interface, such as that of a wetting meniscus is a classic multi-scale problem of vital significance to many fields of science and engineering. However, a complete description of the local evaporative flux at all length scales, especially without arbitrary tuning of boundary conditions, is lacking. A multi-scale method to model evaporation from steady meniscus is described such that a need for tuning of boundary conditions and additional assumptions are alleviated. A meniscus submodel is used to compute evaporation flux in the bulk meniscus while a transition film submodel is used to account for enhanced evaporation near the contact line. A unique coupling between the meniscus and transition film submodels ensures smooth continuity of both film and mass flux profiles along the meniscus. The local mass flux is then integrated over the interfacial area to investigate the contribution from the different regions on the surface. The model is evaluated with data from cryo-neutron phase change tests conducted previously at NIST . It is found that the peak mass flux in the transition region is 2 orders of magnitude greater than the flux at the apex. Despite the enhanced evaporation in the thin film, it was found that 78-95% of the evaporation occurs in the bulk meniscus due to the large area. The bulk meniscus contribution increases with increase in vapor pressure and Bond number but decreases with an increase in thermal conductivity of the substrate. Using a non-uniform temperature boundary suggests that there is a possibility that the adsorbed film may have a non-zero mass flux.

中文翻译:

用于润湿液中稳定弯月面蒸发的多尺度方法

沿着弯曲的液体蒸汽界面(如湿弯月面的界面)蒸发是一个经典的多尺度问题,对许多科学和工程领域都具有至关重要的意义。但是,缺乏对所有长度尺度上的局部蒸发通量的完整描述,尤其是在没有任意调整边界条件的情况下。描述了一种用于模拟稳定弯月面蒸发的多尺度方法,从而减轻了对边界条件进行调整的需要和其他假设。弯月面子模型用于计算整体弯月面的蒸发通量,而过渡膜子模型用于说明接触线附近的蒸发增加。弯月面和过渡膜子模型之间的独特耦合可确保沿弯月面的膜通量和质量通量分布图的平滑连续性。然后,在界面区域上积分局部质量通量,以研究表面上不同区域的贡献。使用先前在NIST进行的低温中子相变测试的数据评估模型。发现过渡区域的峰值质量通量比顶点处的通量大2个数量级。尽管薄膜中的蒸发增强了,但是发现由于大面积,在整体弯液面中发生了78-95%的蒸发。弯月面的整体贡献随着蒸气压和键数的增加而增加,但是随着基底的导热率的增加而减小。使用不均匀的温度边界表明,吸附的膜可能具有非零的质量通量。
更新日期:2020-01-09
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