Experimental observations of the dissolution of calcium sulfate by flowing water have been used to investigate the assumptions underlying pore-scale models of reactive transport. Microfluidic experiments were designed to observe changes in size and shape as cylindrical disks (radius 10 mm) of gypsum dissolved for periods of up to 40 days. The dissolution flux over the whole surface of the sample can be determined by observing the motion of the interface. However, in order to extract surface reaction rates, numerical simulations are required to account for diffusional hindrance across the concentration boundary layer; the geometry is too complex for analytic solutions. We have found that a first-principles simulation of pore-scale flow and transport, with a single value of the surface reaction rate, was able to reproduce the time sequence of sample shapes without any fitting parameters. The value of the rate constant is close to recent experimental measurements but much smaller than some earlier values. The shape evolution is a more stringent test of the validity of the method than average measurements such as effluent concentration, because it requires the correct flux at each point on the sample surface.

中文翻译：

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溶解矿物颗粒的时间相关形状：模拟与微流体实验的比较

通过流动的水溶解硫酸钙的实验观察已被用于研究反应输运的孔隙尺度模型的假设。微流体实验旨在观察石膏的圆柱形圆盘（半径 10 毫米）在长达 40 天的时间内溶解时尺寸和形状的变化。样品整个表面的溶解通量可以通过观察界面的运动来确定。然而，为了提取表面反应速率，需要数值模拟来解释跨越浓度边界层的扩散障碍；几何对于解析解来说太复杂了。我们发现，孔隙尺度流动和输运的第一性原理模拟，具有单一的表面反应速率值，能够在没有任何拟合参数的情况下重现样本形状的时间序列。速率常数的值接近最近的实验测量值，但比一些早期的值小得多。形状演变是对方法有效性的更严格的测试，而不是像流出物浓度这样的平均测量值，因为它需要样品表面每个点的正确通量。