| Imbibition is an important research topic,especially in complex structures.The purpose of this paper is to use the phase field method to realize the interface tracing in the imbibition process and the imbibition analysis in the complex variable section structure.Compared with other interface tracking method,the phase field method has strong adaptability,simple operation,without having to manually capillary pressure and can be observed surface micro advantages,such as the change of the topological structure and the use of phase field method to study the imbibition analysis of the papers are very few,therefore,through the analysis of this paper,the phase field method is a kind of imbibition problems in the study of variable cross-section good tools.At the same time,the research on the concave-convex-concave transformation process of the meniscus at the abrupt cross section is also blank.This paper aims to help you better understand the transformation process of the meniscus at the abrupt cross section by studying the meniscus transformation process.In this paper,phase field method is employed to solve dynamical imbibition problem in various geometries,including straight tube,conical tube and structures in which the topology changes.The variation of the imbibition height with respect to time from phase field simulation is verified with theoretical predictions from Lucas-Washburn law in a straight capillary tube with three gravitational scenarios.In addition,the capillary pressure and velocity field are found to be consistent with Laplace-Young equation and HagenPoiseuille equation in various geometries.The applicability and accuracy of the phase field method for the study of imbibition in structures with changing topology are also discussed.When fluid passes through the abrupt cross section,there is a concave-convex-concave transformation process at the front of the meniscus.This paper analyzes the meniscus transformation process at the abrupt cross section through experiments,and finds that the transformation process is related to inertial force,viscous force and surface tension.In the process of the convex meniscus transformation,the mean curvature radius is negatively correlated with the weber number We,negatively correlated with the capillary number Ca,and positively correlated with the inner diameter ratio of the abrupt section and the initial inner radius.This conclusion will provide some theoretical guidance for the capillary seepage design at the abrupt section. |
