Numerical Study On Sound Propagation In Microchannel With Two-phase Flow Via Lattice Boltzmann Method

The propagation of sound waves in two-phase porous media is widely exist in life,nature and engineering,such as sonic detection of gas content in seafloor sediments,safety monitoring of CO₂ reservoir by sound waves,and droplet microcontrol technology.In recent years,the research on the two-phase flow has been very rich.The study of the sound waves in two-phase porous medium has been paid more and more attention.However,because of the complex interface capture,calculation of surface tension,gas-liquid-acoustic coupling,most scholars use experiments to study this direction.The understanding of physical law and influence mechanism is not enough.The traditional numerical method is complicated in calculating the interface and needs to calculate the Poisson equation to obtain the sound field.In recent years,the lattice Boltzmann method（LBM）has developed rapidly,with advantages in calculating two-phase flow and acoustic propagation.However,few scholars have studied it at present.So,we discuss it in this paper.In this paper,a two-phase LBM based on the phase-field model is used to study the acoustic propagation in two-phase flow.LBM based on phase field model has the advantages of stable calculation,easy calculation of complex phase interface and clear physical significance.It has been proved to be an effective method to study two-phase fluid flow.We simplify the porous medium into a pipe.In this way,without affecting the basic physical laws of the problem,the feasibility of the method can be explored and the physical laws can be preliminarily studied to pave the way for the later complex studies.The research of this paper is divided into two parts:（1）LBM based on the phase field model was used to build the two-phase flow sound propagation model in the pipeline.The validity of this method in calculating acoustic wave problem is verified.The influence of bubbles on the attenuation of sound waves is further analyzed by numerical simulation.The conclusions are as follows:（1）LBM based on phase field model has the ability to describe sound propagation and sound pressure attenuation.（2）The larger the bubble radius,the faster the sound wave decays.（3）The more bubbles,the faster the sound waves decay.（2）For the traditional phase field model,the phase interface needs a certain thickness.A LBM for two-phase flow based on a sharp interface phase field model is proposed to make it more suitable for the study of porous media.The results show that the new model can achieve the same precision as the previous model with a much thinner phase interface.