Qin Feifei, Zhao Jianlin, Kang Qinjun, Derome Dominique, Carmeliet Jan
Chair of Building Physics, Department of Mechanical and Process Engineering, ETH Zürich (Swiss Federal Institute of Technology in Zürich), 8092 Zürich, Switzerland.
Earth and Environment Sciences Division (EES-16), Los Alamos National Laboratory (LANL), Los Alamos, NM 87545 USA.
Transp Porous Media. 2021;140(1):395-420. doi: 10.1007/s11242-021-01644-9. Epub 2021 Jul 10.
Drying of porous media is governed by a combination of evaporation and movement of the liquid phase within the porous structure. Contact angle hysteresis induced by surface roughness is shown to influence multi-phase flows, such as contact line motion of droplet, phase distribution during drainage and coffee ring formed after droplet drying in constant contact radius mode. However, the influence of contact angle hysteresis on liquid drying in porous media is still an unanswered question. Lattice Boltzmann model (LBM) is an advanced numerical approach increasingly used to study phase change problems including drying. In this paper, based on a geometric formulation scheme to prescribe contact angle, we implement a contact angle hysteresis model within the framework of a two-phase pseudopotential LBM. The capability and accuracy of prescribing and automatically measuring contact angles over a large range are tested and validated by simulating droplets sitting on flat and curved surfaces. Afterward, the proposed contact angle hysteresis model is validated by modeling droplet drying on flat and curved surfaces. Then, drying of two connected capillary tubes is studied, considering the influence of different contact angle hysteresis ranges on drying dynamics. Finally, the model is applied to study drying of a dual-porosity porous medium, where phase distribution and drying rate are compared with and without contact angle hysteresis. The proposed model is shown to be capable of dealing with different contact angle hysteresis ranges accurately and of capturing the physical mechanisms during drying in different porous media including flat and curved geometries.
The online version contains supplementary material available at 10.1007/s11242-021-01644-9.
多孔介质的干燥过程受多孔结构内蒸发和液相运动的共同作用影响。研究表明，由表面粗糙度引起的接触角滞后会影响多相流，例如液滴的接触线运动、排水过程中的相分布以及在恒定接触半径模式下液滴干燥后形成的咖啡环。然而，接触角滞后对多孔介质中液体干燥的影响仍是一个未解之谜。格子玻尔兹曼模型（LBM）是一种先进的数值方法，越来越多地用于研究包括干燥在内的相变问题。在本文中，基于一种规定接触角的几何公式化方案，我们在两相伪势LBM框架内实现了一个接触角滞后模型。通过模拟放置在平面和曲面上的液滴，测试并验证了在大范围内规定和自动测量接触角的能力和准确性。随后，通过对平面和曲面上液滴干燥进行建模，验证了所提出的接触角滞后模型。然后，研究了两根相连毛细管的干燥过程，考虑了不同接触角滞后范围对干燥动力学的影响。最后，将该模型应用于研究双孔隙率多孔介质的干燥过程，比较了有无接触角滞后时的相分布和干燥速率。结果表明，所提出的模型能够准确处理不同的接触角滞后范围，并能捕捉包括平面和曲面几何形状在内的不同多孔介质干燥过程中的物理机制。
在线版本包含可在10.1007/s11242-021-01644-9获取的补充材料。
