Effects of compound-specific transverse mixing on steady-state reactive plumes: Insights from pore-scale simulations and Darcy-scale experiments
Effects of compound-specific transverse mixing on steady-state reactive plumes: Insights from pore-scale simulations and Darcy-scale experiments
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DOI：
10.1016/j.advwatres.2012.12.007
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发表时间：
2013-04
影响因子：
4.7
通讯作者：
D. L. Hochstetler;M. Rolle;G. Chiogna;C. Haberer;P. Grathwohl;P. Kitanidis
中科院分区：
文献类型：
--
作者：
D. L. Hochstetler;M. Rolle;G. Chiogna;C. Haberer;P. Grathwohl;P. Kitanidis
横向混合对于多孔介质中的反应是至关重要的，最近的研究表明，要在达西尺度上描述这种混合，横向分散的非线性化合物特有的参数化是必要的。我们研究了这种横向混合描述在预测反应输运中的有效性。我们进行了孔洞尺度的数值模拟和流动实验室实验，以研究连续注入反应物时的混合限制反应，这些反应会导致稳定的反应羽流。我们认为产物质量通量和反应物羽流长度是反应输运的量度。这项研究表明，横向弥散的非线性参数化在两个数量级的平均流速范围内一致地预测产物质量通量和反应物羽流范围。相反，经典的横向弥散的线性参数，假设一个恒定的弥散率作为多孔介质的一个属性，不能一致地以很高的精度预测这两个指标。此外，横向色散的线性参数表示羽流长度随速度的增加而渐近(恒定)，而非线性参数表示羽流长度随速度的平方根增加。无论是孔隙尺度的模型模拟，还是混合受限反应输运的实验室实验，都表明了后一种关系。
Transverse mixing is critical for reactions in porous media and recent studies have shown that to characterize such mixing at the Darcy scale a nonlinear compound-specific parameterization of transverse dispersion is necessary. We investigate the effectiveness of this description of transverse mixing in predicting reactive transport. We perform pore-scale numerical simulations and flow-through laboratory experiments to study mixing-limited reactions with continuous injection of reactants that result in steady-state reactive plumes. We consider product mass flux and reactant plume lengths as metrics of reactive transport. This study shows that the nonlinear parameterization of transverse dispersion consistently predicts both product mass flux and reactant plume extents across two orders of magnitude of mean flow velocities. In contrast, the classical linear parameterization of transverse dispersion, assuming a constant dispersivity as a property of the porous medium, could not consistently predict either indicator with great accuracy. Furthermore, the linear parameterization of transverse dispersion predicts an asymptotic (constant) plume length with increasing velocity while the nonlinear parameterization indicates that the plume length increases with the square root of the velocity. Both the pore-scale model simulations and the laboratory experiments of mixing-limited reactive transport show the latter relationship.