Watercolor-paper-TBP-PSBMA-BD-u-3.1.txt from Capillary transport in paper porous materials at low saturation levels: normal, fast or superfast?

The problem of capillary transport in fibrous porous materials at low levels of liquid saturation has been addressed. It has been demonstrated that the process of liquid spreading in this type of porous material at low saturation can be described macroscopically by a similar super-fast, nonlinear diffusion model to that which had been previously identified in experiments and simulations in particulate porous media. The macroscopic diffusion model has been underpinned by simulations using a microscopic network model. The theoretical results have been qualitatively compared with available experimental observations within the witness card technique using persistent liquids. The long-term evolution of the wetting spots was found to be truly universal and fully in line with the mathematical model developed. The result has important repercussions for the witness card technique used in field measurements of the dissemination of various low-volatility agents in imposing severe restrictions on collection and measurement times.本研究针对低液体饱和度下纤维多孔材料内的毛细输运问题展开了探讨。研究证实，此类低饱和度多孔材料内的液体铺展过程，可通过宏观尺度下的超快非线性扩散模型进行描述，该模型与此前在颗粒多孔介质的实验与模拟中得到的模型形式一致。该宏观扩散模型的合理性已通过微观网络模型的模拟结果得到支撑与验证。理论结果已通过采用持久性液体的示踪卡技术（witness card technique）获取的现有实验观测结果完成定性对比。研究发现，润湿斑的长期演化过程具备真正的普适性，且与所构建的数学模型完全吻合。该研究结果对采用示踪卡技术开展的现场测量工作具有重要意义：这类现场测量用于检测各类低挥发试剂的扩散行为，且对样品采集与测量时长存在严格限制。