Hydrodynamic dispersion and mass transfer in unsaturated flow
Hydrodynamic dispersion and mass transfer in unsaturated flow
复制标题
非饱和流中的流体动力分散和传质
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
T. Chida
中科院分区：
文献类型：
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作者：
Daisuke Haga;Y. Niibori;T. Chida
示踪剂响应实验是使用玻璃微珠填充床进行的，在稳定的非饱和条件下，流体以单相(水)或两相(水和气体)的形式流动。结果与含水饱和度有关，在临界含水饱和度时可分为两个区域，即气相开始不动的饱和度。为了确定水动力弥散系数，将实验响应与一维对流-弥散方程的数值结果进行了比较。结果表明，水动力弥散系数随含水饱和度的降低而增大。此外，在临界饱和度以上和低于临界饱和度时，弥散系数的增加速度也不同。根据两次非饱和渗流实验结果，得到了Peclet数Pe与含水饱和度Sw之间的数学关系式：单相流Pe=0.8Sw1.2，两相流Pe=0.9Sw3.1。在单相流关系式中，当Sw=1时，Pe的值在先前报道的范围内。利用两相流动关系式分析了两相示踪剂(氨-水溶液)在非饱和床层中的传质过程。
Tracer response experiments were carried out using a packed bed of glass beads, where fluid flowed as either a single phase (water) or two phases (water and gas) under steady unsaturated conditions. The results depended on the water saturation and could be divided into two regions at the critical water saturation, that is, the saturation at which the gas phase began to be immobile. To determine the hydrodynamic dispersion coefficients, the experimental responses were compared with the numerical results of a one‐dimensional advection‐dispersion equation. These results demonstrated that the hydrodynamic dispersion coefficients increased with a decrease in water saturation. Furthermore, the rates of the increase in the dispersion coefficients above the critical saturation were different from those below it. The following mathematical relations between the Peclet number, Pe, and the water saturation, Sw, were obtained from the results of the two unsaturated flow experiments: Pe=0.8Sw1.2 for single‐phase flow and Pe=0.9Sw3.1 for two‐phase flow. When Sw=1 in the relation for single‐phase flow, the value of Pe is in a range that has been reported previously. The relation for two‐phase flow was used to analyze the mass transport of the two‐phase tracer (ammonia‐water solution) through unsaturated beds.