UPSCALING TRANSPORTOF ADSORBING SOLUTES IN POROUS MEDIA
UPSCALING TRANSPORTOF ADSORBING SOLUTES IN POROUS MEDIA
复制标题
提高多孔介质中吸附溶质的传输
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
S. Hassanizadeh
中科院分区：
文献类型：
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作者：
A. Raoof;S. Hassanizadeh
溶质在多孔介质中的吸附通常被模拟为一个平衡过程。实际上，我们可以有把握地假设，在孔隙空间内，颗粒表面某一点上吸附的溶质浓度与颗粒旁边流体中的浓度在代数上是相关的。然而，平均浓度就不是这样了。事实上，在溶质运输过程中，孔隙空间内会形成浓度梯度，这可能会导致依赖于尺度的吸附过程。本研究的主要目的是建立孔尺度吸附系数与相应的升级吸附参数之间的关系。采用了两种方法：理论平均和数值上尺度。在平均方法中，假设在孔隙尺度上吸附平衡，溶质输运方程在rev上平均。这导致宏观尺度吸附速率常数作为微观尺度参数的函数的显式表达式。在数值方法中，我们首先模拟溶质在单管中在孔壁上进行平衡吸附，然后得到通量平均浓度突破曲线。这些用于确定作为孔隙尺度水力和吸附参数函数的升级吸附速率常数。两种方法的结果非常吻合。
Adsorption of solutes in porous media is commonly modeled as an equilibrium process. Indeed, one may safely assume that within the pore space, the concentration of adsorbed solute at a point on the grain surface is algebraically related to the concentration in the fluid next to the grain. The same, however, cannot be said about average concentrations. In fact, during solute transport, concentration gradients develop within the pore space, and these could potentially give rise to a scale-dependent adsorption process. The main objective of this research is to develop relationship between porescale adsorption coefficient and corresponding upscaled adsorption parameters. Two approaches are used: Theoretical averaging and numerical upscaling. In the averaging approach, equilibrium adsorption is assumed at the pore-scale and solute transport equations are averaged over REV. This leads to explicit expressions for macro-scale adsorption rate constants as a function of micro-scale parameters. In the numerical approach, first we simulate solute transport within a single tube undergoing equilibrium adsorption at the pore wall, and then flux averaged concentration breakthrough curves are obtained. These are used to determine the upscaled adsorption rate constants as functions of pore-scale hydraulic and adsorption parameters. Results of the two approaches agree very well.