ABSTRACT The behavior of water in porous media under variable gravities should be known for establishing agriculture in space. The effects of surface tension and viscosity may be emphasized under microgravity, where the weight is canceled and the density term can be ignored. In this article, the effects of changes in surface tension and viscosity were evaluated on horizontal infiltration, which is not influenced by gravity. A new equation with two dimensionless parameters was derived by performing dimensional analysis for horizontal water movement in porous media. A new term, the S-N number, is proposed as the ratio of surface tension and viscosity. Horizontal infiltration experiments with various concentrations of aqueous ethanol solutions were performed, and infiltration rates were measured. Horizontal infiltration rates were assessed with the newly proposed S-N number and the with the fluid mobility factor (defined as the ratio of density to viscosity). The S-N number and infiltration rates were linearly correlated with r = 0.95; thus, the S-N number could be an alternative indicator to the fluid mobility factor for the relative mobility of infiltrating liquids. For higher ethanol concentrations, a sharp wetting front collapsed and blurred due to decreases in the surface tension of ethanol solutions. The proposed S-N number is valid under any gravitational condition and so can be used to estimate mobility even under variable gravity.

中文翻译：

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受液体表面张力和粘度影响的水平渗透量纲分析

摘要 水在可变重力下多孔介质中的行为应该为在太空中建立农业而闻名。在微重力下，表面张力和粘度的影响可能会被强调，其中重量被抵消，密度项可以忽略。在本文中，表面张力和粘度变化对水平渗透的影响进行了评估，水平渗透不受重力影响。通过对多孔介质中水的水平运动进行量纲分析，推导出具有两个无量纲参数的新方程。提出了一个新术语 SN 数作为表面张力和粘度的比率。用不同浓度的乙醇水溶液进行水平渗透实验，并测量渗透率。水平渗透率通过新提出的 SN 数和流体流动系数（定义为密度与粘度的比率）进行评估。SN 数和浸润率与 r = 0.95 呈线性相关；因此，SN 数可能是渗透液体相对流动性的流体流动性因子的替代指标。对于更高的乙醇浓度，由于乙醇溶液表面张力的降低，尖锐的润湿前沿坍塌和模糊。提议的 SN 数在任何重力条件下都是有效的，因此即使在可变重力下也可用于估计流动性。SN 数可能是渗透液体相对流动性的流体流动性因子的替代指标。对于更高的乙醇浓度，由于乙醇溶液表面张力的降低，尖锐的润湿前沿坍塌和模糊。提议的 SN 数在任何重力条件下都是有效的，因此即使在可变重力下也可用于估计流动性。SN 数可能是渗透液体相对流动性的流体流动性因子的替代指标。对于更高的乙醇浓度，由于乙醇溶液表面张力的降低，尖锐的润湿前沿坍塌和模糊。提议的 SN 数在任何重力条件下都是有效的，因此即使在可变重力下也可用于估计流动性。