HYPOTHESIS Capillary-dominated multiphase flow in porous materials is strongly affected by the pore walls' wettability. Recent micro-computed tomography (mCT) studies found unexpectedly wide contact angle distributions measured on static fluid distributions inside the pores. We hypothesize that analysis on time-resolved mCT data of fluid invasion events may be more directly relevant to the fluid dynamics. EXPERIMENT We approximated receding contact angles locally in time and space on time-resolved mCT datasets of drainage in a glass bead pack and a limestone. Whenever a meniscus suddenly entered one or more pores, geometric and thermodynamically consistent contact angles in the surrounding pores were measured in the time step just prior to the displacement event. We introduced a new force-based contact angle, defined to recover the measured capillary pressure in the invaded pore throat prior to interface movement. FINDINGS Unlike the classical method, the new geometric and force-based contact angles followed plausible, narrower distributions and were mutually consistent. We were unable to obtain credible results with the thermodynamically consistent method, likely because of sensitivity to common imaging artifacts and neglecting dissipation. Time-resolved mCT analysis can yield a more appropriate wettability characterization for pore scale models, despite the need to further reduce image analysis uncertainties.

中文翻译：

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使用时间分辨微型计算机断层扫描在多孔介质内进行基于事件的接触角测量。

假设多孔材料中以毛细管为主的多相流受孔壁润湿性的强烈影响。最近的微型计算机断层扫描 (mCT) 研究发现，在孔隙内的静态流体分布上测得的接触角分布出乎意料地宽。我们假设对流体入侵事件的时间分辨 mCT 数据的分析可能与流体动力学更直接相关。实验我们在玻璃珠包和石灰石中排水的时间分辨 mCT 数据集上在时间和空间上局部地近似后退接触角。每当弯月面突然进入一个或多个孔隙时，就在位移事件之前的时间步长中测量周围孔隙中几何和热力学一致的接触角。我们引入了一种新的基于力的接触角，定义为在界面运动之前恢复侵入孔喉中测量的毛细管压力。发现与经典方法不同，新的几何和基于力的接触角遵循合理的、更窄的分布并且相互一致。我们无法使用热力学一致的方法获得可靠的结果，这可能是因为对常见的成像伪影敏感并且忽略了耗散。尽管需要进一步降低图像分析的不确定性，但时间分辨 mCT 分析可以为孔隙尺度模型产生更合适的润湿性表征。我们无法使用热力学一致的方法获得可靠的结果，这可能是因为对常见的成像伪影敏感并且忽略了耗散。尽管需要进一步降低图像分析的不确定性，但时间分辨 mCT 分析可以为孔隙尺度模型产生更合适的润湿性表征。我们无法使用热力学一致的方法获得可靠的结果，这可能是因为对常见的成像伪影敏感并且忽略了耗散。尽管需要进一步降低图像分析的不确定性，但时间分辨 mCT 分析可以为孔隙尺度模型产生更合适的润湿性表征。