微孔中反应流体黏性指进混合过程的数值研究

Numerical Study on Reactive Mixing of Miscible Solutions With Viscous Fingering in Micro-pores

基于国家数值风洞LBM模块和自编程序,本文在孔隙尺度下对微孔中两种可混溶溶液的黏性指进反应混合过程进行了数值研究。针对两种溶液之间的化学反应以及产物的析出,本文重点研究化学反应速率、固态生成物的成核速率以及聚集速率对黏性指进的影响。研究发现:反应会明显改变黏性指进的界面浓度分布,一方面随着反应速率的增加,指进界面处各组分的变化越来越明显;另一方面由于受到扩散作用的限制,当反应速率增大到一定值后,各组分的平均浓度不再发生变化;产物的生成量与反应速率成正相关,与成核速率和聚集速率成负相关;析出的固相组分的浓度与成核速率和聚集速率成正相关;混合长度主要和反应速率相关,成核速率以及聚集速度的改变对混合长度基本没有影响。

In this paper, the reactive mixing process with viscous fingering of two miscible solutions in micro-pores is studied at pore scale based on the LBM modules of the National Numerical Wind Tunnel software. Considering the chemical reaction between the two solutions and the precipitation of reaction product, we focuse on the effects of the chemical reaction rate, the nucleation rate and the aggregation rate of the solid product on the viscosity fingering. It is found that the chemical reaction obviously changes the concentration distribution of the interface of the viscous finger, and the change of the components at the finger interface increases with the chemical reaction rate. On the other hand, when the reaction rate increases above a certain value, the concentration remains nearly constant due to the limitation of diffusion process. In addition, the amount of reaction product is positively correlated with the reaction rate and negatively correlated with the nucleation rate and aggregation rate, and the concentration of solid component is positively correlated with the nucleation rate and aggregation rate positively. Finally, it is found that the mixing length is mainly related to the chemical reaction rate, nearly independent on the nucleation and aggregation rates.