Modelling of spreading, imbibition and evaporation of liquids on structured or porous deformable substrates

液体在具有粗糙度、地形或多孔涂层的可变形表面上的扩散、吸胀和蒸发对于许多工业应用都很重要。这些现象是多尺度的，不能用宏观方法来描述，因为宏观方法忽略了分子间相互作用的影响。该项目旨在开发液体在结构或多孔可变形基质上扩散、吸胀和蒸发的模型，并考虑到采用分离压力概念描述的表面力的影响。在第一个资助期内，采用基于薄膜理论的数值模型研究了高度与表面力作用范围相当的液滴的静态和动态润湿。研究发现，当纳米液滴在可变形固体上扩散时，润湿脊会表现出非单调动力学。脊形的演变取决于分离压力等温线的参数。研究了拐角几何形状中毛细管驱动的流动。地表力已被证明可以确定开放楔形河道中水流的最大长度。值得注意的是，当忽略地表力时，稳定的水流是无法预测的。在下一个资助期内，开发的模型将得到扩展，并用于描述液体在纳米孔中的扩散、抑制和蒸发，在具有地形和机械性能不均匀分布的可变形表面上，以及在包含薄柔性片、片层和纤维的系统中。这些研究的结果将有助于阐明在整个多孔结构尺度上控制渗吸的关键现象。计算有效输运系数的均匀化技术将在此知识的基础上应用。这些系数将用于宏观尺度模拟结构或多孔可变形基质上的吸胀和蒸发，这与自然现象和技术应用有关。仿真结果将与实验数据进行对比验证。

Spreading, imbibition and evaporation of liquids on deformable surfaces with roughness, topography or with porous coatings is important for numerous industrial applications. These phenomena are multiscale and cannot be described using the macroscopic approach, which ignores the effect of intermolecular interactions. The project is aimed at development of models for spreading, imbibition and evaporation of liquids on structured or porous deformable substrates and takes into account the effects of the surface forces, described employing the disjoining pressure concept. In the first funding period, the static and dynamic wetting of the droplets with height comparable with the range of surface force action has been studied using a thin film theory-based numerical model. It has been found that if the nanodrop spreads over a deformable solid, the wetting ridge can exhibit a non-monotonic dynamics. The evolution of the ridge shape depends on the parameters of the disjoining pressure isotherm. The capillary-driven flow in corner geometries has been studied. The surface forces have been shown to define the maximal length of rivulets in open wedge channels. Remarkably, the steady rivulets cannot be predicted when the surface forces are ignored. In the next funding period the developed models will be extended and used to describe the liquid spreading, imibibition and evaporation in nanopores, on deformable surfaces with topography and inhomogeneous distribution of mechanical properties, as well as in systems containing thin flexible sheets, lamellas and fibers. The results of these studies will allow elucidating the key phenomena governing imbibition on a scale of the whole porous structure. Homogenization techniques for computation of effective transport coefficients will be applied on the basis of this knowledge. These coefficients will be used for macroscopic-scale simulation of imbibition and evaporation on structured or porous deformable substrates, which are relevant to natural phenomena and technological applications. The results of simulations will be validated by comparison with experimental data.