液桥的动态界面特性对液-液自发渗吸的影响研究

STUDY ON THE EFFECT OF DYNAMIC INTERFACIAL PROPERTIES OF LIQUID BRIDGES ON SPONTANEOUS LIQUID-LIQUID IMBIBITION

在自然界和工业应用中,多孔介质中的多相流动现象普遍存在,如地下水流动、油气开采、非饱和颗粒材料等.在这些过程中,液桥的存在对多相流动产生显著影响.基于改进的液-液自发渗吸理论模型及改进流-固作用力格式的两组分Shan-Chen模型,研究了液桥的存在对毛细管内液-液自发渗吸的影响.结果表明:与不含液桥的渗吸过程相比,液桥的存在使得毛细管内产生3个界面,显著增大了系统的动态接触角,降低自发渗吸速度.随着润湿性的增强,液桥的存在使得界面动态变化特性增强的幅度更大.当液桥的黏度小于非润湿流体的黏度时,整个系统的动态接触角随着渗吸长度的增加而增强;若二者黏度相等,整个系统的动态接触角为一稳定值;而当液桥的黏度更大时,整个系统的动态接触角随着渗吸的进行逐渐减小.将模拟获得的实时动态接触角纳入至渗吸理论中,可以改善由液桥界面动态变化导致的渗吸长度的理论值与模拟结果间存在的偏差,并得到与模拟基本一致的结果.文章还利用模拟数据,系统地评价了Cox-Voinov模型对含有液桥以及不含液桥体系的渗吸过程中的界面动态变化特性及渗吸长度预测能力.

The phenomenon of multiphase flow in porous media occurs widely in both natural and industrial applications,including groundwater flow,oil and gas development,and unsaturated particulate materials.Liquid bridges play a crucial role in these processes and significantly influence the dynamics of multiphase flows.In this work,we have investigated the effect of liquid bridges on spontaneous liquid-liquid imbibition in capillaries based on a modified spontaneous liquid-liquid imbibition theory model and a two-component Shan-Chen model with an improved fluid-solid interaction force format.The results indicate that the presence of liquid bridges leads to the formation of three interfaces within the capillary,which significantly increases the dynamic contact angles of the entire system and reduces the rate of spontaneous imbibition compared to processes without liquid bridges.Additionally,with the increase of wettability,the presence of liquid bridges enhances the dynamic interface change characteristics more strongly.When the viscosity of the liquid bridge is lower than that of the non-wetting fluids,an increase in the imbibition length will enhance the dynamic contact angles of the entire system;if they both have equal-sized viscosities,then the dynamic contact angles of the entire system remain a constant;and when the viscosity of the liquid bridge is larger than that of the non-wetting fluids,there is a gradual decrease in the dynamic contact angle during imbibition.By incorporating the real-time dynamic contact angle obtained from the simulation into the imbibition theory,the deviation between the theoretical and simulated imbibition lengths due to the dynamic changes of the liquid-bridge interface can be improved,and the results are consistent with the simulation.In this study,we also systematically evaluated the predictive ability of Cox-Voinov models for interface dynamic variation and imbibition length in imbibition processes with and without liquid bridges by using the data from the simulation.