During evaporation in porous media, two types of corner films are distinguished. A continuous corner film is connected to the bulk liquid, while a discontinuous one is not. To disclose their effects on evaporation in porous media, a pore network model with both continuous and discontinuous corner films is developed, which considers the capillary and viscous forces as well as the effects of corner films on the threshold pressures of pores. The capillary valve effect induced by the sudden geometrical expansion between the small and large pores is also taken into account in the model. The developed pore network model agrees well with the evaporation experiment with a quasi-two-dimensional micromodel porous medium, in terms of not only the variation of the liquid saturation in each pore but also the variation of the total evaporation rate. The pore network models that neglect the corner films or the liquid viscosity are also compared with the experiment so as to shed light on the roles of the corner films. The continuous corner films, which contribute to sustain the high evaporation rate, can be interrupted to be the discontinuous ones not only by the gas invasion into pores but also by the capillary scissors effect due to the local convex topology of the solid matrix.

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具有连续和不连续角膜的多孔介质中蒸发的孔网络模型

在多孔介质中蒸发期间，区分了两种类型的角膜。连续的角膜连接到散装液体，而不连续的角膜则没有。为了揭示它们对多孔介质中蒸发的影响，建立了具有连续和不连续角膜的孔网络模型，该模型考虑了毛细作用力和粘性力以及角膜对孔的阈值压力的影响。在模型中还考虑了由小孔和大孔之间突然的几何膨胀引起的毛细管阀效应。所开发的孔隙网络模型与准二维微模型多孔介质的蒸发实验非常吻合，不仅在每个孔隙中的液体饱和度变化方面，而且在总蒸发速率方面都变化不大。还将忽略角膜或液体粘度的孔网络模型与实验进行了比较，以阐明角膜的作用。有助于维持高蒸发速率的连续角膜，不仅可以被气体侵入孔中，还可以由于固体基质的局部凸形拓扑而被毛细剪刀效应中断，成为不连续的角膜。