Transport of conservative chemical through an unsaturated two‐dimensional Miller‐similar medium with steady state flow
Transport of conservative chemical through an unsaturated two‐dimensional Miller‐similar medium with steady state flow
复制标题
保守化学物质通过稳态流的不饱和二维米勒相似介质的传输
DOI：
10.1029/96wr00756
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发表时间：
1996
影响因子：
5.4
通讯作者：
K. Hammel
中科院分区：
文献类型：
--
作者：
K. Roth;K. Hammel
对二维、宏观均匀、米勒相似介质中水流的数值模拟表明，存在由临界点分隔开的具有两种互补状态的流动通道网络[Roth，1995]。通过使用粒子跟踪的数值模拟来探索这对溶质运输的影响。研究发现，这些模拟定性地再现了许多实验观察到的土壤传输特征。分析结果表明，在相应的有效介质中，过渡到对流色散的传播距离和有效色散率取决于水通量。特别是，有效纵向色散率（通常被假定为多孔结构的材料常数）被发现变化超过一个数量级，最小值接近临界点。模拟进一步表明，速度场的局部结构和小尺度流体动力色散对于场平均输运过程并不重要。
Numerical simulation of water flow in a two-dimensional, macroscopically homogeneous, Miller-similar medium showed the existence of a network of flow channels with two complementary states separated by a critical point [Roth, 1995]. The consequences of this for solute transport are explored by numerical simulations using particle tracking. It is found that many experimentally observed features of transport through soil are reproduced qualitatively by these simulations. Analyzing the results reveals that in the corresponding effective medium the travel distance for the transition to convection-dispersion and the effective dispersivity depend on the water flux. In particular, the effective longitudinal dispersivity, which is often assumed to be a material constant of the porous structure, is found to vary by more than an order of magnitude with a minimum near the critical point. The simulations further demonstrate that the local structure of the velocity field and the subscale hydrodynamic dispersion are of minor importance for the field-averaged transport process.