Pore‐scale dilution of conservative solutes: An example
Pore‐scale dilution of conservative solutes: An example
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DOI：
10.1029/98wr01468
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发表时间：
1998-08
影响因子：
5.4
通讯作者：
J. Cao;P. Kitanidis
中科院分区：
文献类型：
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作者：
J. Cao;P. Kitanidis
我们用有限元技术模拟了保守的非吸附示踪剂在理想化周期孔道中的流动和输运。计算浓度，然后通过对每个电池进行平均，计算出缓慢变化的浓度平均值、方差、变异系数和反应器比。变异系数与反应器比相关，量化了稀释程度。然后发展了一种新的方法来评估宏观参数(均化)，包括衡量小尺度浓度波动趋于减弱的速率的方差衰减系数，以及浓度方差与平均浓度方差的平方之间的大时间比例系数。该方法基于求解单个单元(作为代表性的基本体积)中的定常平流-弥散问题；然后对计算结果进行积分以计算宏观参数。将这些参数与在逐个单元的基础上通过直接模拟计算的参数进行比较，发现它们相当吻合。当宏观参数被用于宏观方程时，它们产生的浓度均值和方差的估计与直接模拟的结果一致。
We simulate flow and transport of a conservative nonsorbing tracer in an idealized periodic pore channel using finite element techniques. The concentration is computed; then the slowly varying concentration mean, variance, coefficient of variation, and reactor ratio are calculated through averaging over every cell. The coefficient of variation and reactor ratio are related and quantify the degree of dilution. Then a novel methodology is developed for the evaluation of macroscopic parameters (homogenization), including the variance decay coefficient, which measures the rate with which small‐scale concentration fluctuations tend to diminish, and the large‐time coefficient of proportionality between the concentration variance and the square of the mean concentration variance. The methodology is based on the solution of a steady advection‐dispersion problem in a single cell (which acts as a representative elementary volume); the computed result is then integrated in order to compute the macroscopic parameters. These parameters are compared with the parameters computed through direct simulation on a cell‐by‐cell basis, and they are found to be in reasonably good agreement. When the macroscopic parameters are used in the macroscopic equations, they produce estimates of the concentration mean and variance that are in agreement with the results of direct simulation.