| Under certain conditions,the droplets formed on the superhydrophobic surface with nanostructures can spontaneously bounce after being merged,which is of great significance for achieving efficient droplet condensation heat transfer,anti-condensation and anti-icing,and surface self-cleaning processes..The study of the conditions required for the bounce to occur after the merging of the droplets has important theoretical and practical value for understanding and understanding the nature of the induced bounce phenomenon after the merging of droplets and for studying the surface of the novel superhydrophobic nanostructured material.At present,many researchers have studied the phenomenon of bounce induced by droplet merging from experimental,theoretical,and numerical simulations,and have achieved a lot of results.The numerical simulation method has been recognized by many researchers because it possesses the advantages of no expensive and time-consuming experiment,continuous and dynamic development of the problem,and the display of phenomena occurring within the material structure.However,there are still some deficiencies in the numerical simulation and problems that need further study.For example,there are still large deviations between theoretical predictions,numerical simulations and experimental results.Numerical simulations are often limited to two-dimensional situations.Three-dimensional simulations in real situations are relatively less.So far,the numerical simulation study of the law of the rebound induced by the merging of droplets on the surface of superhydrophobic nanostructured materials is not systematic,comprehensive and detailed.The lattice Boltzmann method(LBM)in numerical simulation is a new mesoscopic method developed in recent years that uses the microscopic model to simulate the macroscopic behavior of the multiphase flow phenomenon,compared with the traditional method.Its simplicity,locality,natural parallelism,and ability to handle complex boundary problems have become powerful tools for simulating complex flow phenomena.At present,the lattice Boltzmann method has been successfully applied to the simulation research field of porous media flow,multiphase flow,turbulent flow,chemical flow and other complex systems.In this paper,a three-dimensional lattice Boltzmann multiphase flow model based on chemical potential is used to systematically and comprehensively study and analyze the conditions and factors that affect the bounce of a droplet after it merges on the surface of a superhydrophobic nanostructured material,and the process of droplet bundling and bounce.Predict the height of droplet bounce.Firstly,the correctness of the multiphase flow model is verified by using the Laplace’s law;then the simulated results obtained by the two-phase coexistence density simulation experiment are compared with the theoretical values of the two-phase coexistence density obtained by solving the Maxwell isoregion reconstruction.It is well proved that the model has thermodynamic consistency;then the simulation of the spontaneously merging process of the square droplets under the influence of surface tension and the spontaneous integration of two closely spaced droplets is performed,and it is preliminarily verified that the model can simulate correctly.The ability of a simple multi-phase flow behavior;Finally,a validated model was used to numerically simulate and analyze the multi-phase flow complex phenomenon of multiple droplets combined on the surface of superhydrophobic nanostructured materials under different conditions.Whether the droplets can bounce under the specified conditions,incorporate the process of bounce and predict the height of the bounce.The numerical simulation results show that the size and number of merged droplets,surface characteristics of superhydrophobic nanostructured materials,such as the height of the nanocolumns,the distance between the nanocolumns,and the wettability of the material surface(surface contact angle),determine whether or not the droplets are combined.The height at which bounces and bounces can have a significant effect.In general,only a relatively small number of droplets can induce bounce,and the higher the bounce height is,the larger the distance between the nanopillars on the surface of the material is,the less bounce is likely to occur,and the higher the nanocolumns and the greater the surface contact angle It is more prone to bounce phenomenon after the merging of droplets,and the height of the bounce is also higher.These obtained results are consistent with the results obtained by the existing experimental methods.Therefore,we use the three-dimensional lattice Boltzmann multiphase flow model based on the chemical potential to simulate the phenomenon of droplet bounce on the surface of superhydrophobic nanostructured materials,which helps us to understand and understand the phenomenon of induced bounce after droplets are merged.The essence and potential of the study are to provide a theoretical reference for the study of new superhydrophobic nanostructured materials. |
