Analysis Of Acoustic Streaming And Suspended Particle Driven By Sound Wave With Lattice Boltzmann Method

As an efficient,clean drive and control technology,microfluidic flow driven by acoustic waves has unique advantages in the application of MEMS and biochip.It relies mainly on the non-linear dissipation of acoustic waves and the friction of solid walls,resulting in unsteady time-averaged flow,acoustic streaming.Due to the fast process and the small boundary layer of acoustic streaming,its research is very difficult.The current research focuses on the experimental study of its cumulative behavior,and there are few studies on the process and mechanism of acoustic streaming formation.In this paper,the computational aeroacoustics(CAA)method is used to directly solve the lattice Boltzmann equation with multi-relaxation scheme,and the acoutic field and streaming are calculated.In combination with the immersed boundary(IB)method,acoustic streaming effect and acoustic wave driving laws of a suspended particle are also studied.The specific work is as follows:1.Classical examples are used to verify and compare the different relaxation schemes and curved boundaries.It is found that the multi-relaxation scheme can improve the stability of the calculation domain with singularities and multi-block meshes can also improve the numerical accuracy by using local refinement.In addition,the uniform format MGUO curved boundary with high numerical accuracy is proposed.2.The characteristics and accuracy of different non-reflective boundaries are compared by one-dimensional and two-dimensional acoustic attenuation problems.A new nonreflective boundary MNEAL with the best non-reflection effect is proposed,and the y-axis velocity reflectivity of the original format is greatly improved by modifying the LODI.3.The acoustic streaming in standing waves between plates is simulated,and the influence of viscosity and height between plates on the acoustic streaming inside and outside the boundary layer are analyzed.It is found that these factors have more significant influence on internal streaming and that there is only internal streaming when 2H/ 10nd(28).4.Combined with the IB method,the motion law of a suspended particle in standing acoustic streaming is studied,and the influence of different characteristic released position and acoustic streaming on it are analyzed.It is found that the narrow space between a particle and boundary induce highly intensive secondary acoustic streaming balanced with external acoustic streaming,capturing the particle at the boundary layer stagnation point.Finally,the initial velocity at which the particle moves from the boundary layer stagnation point to the center stagnation point and is captured by it,is also given.This paper verifies the feasibility of lattice Boltzmann method to study the acoustic streaming problem,proposes a new non-reflective boundary that can be used for accurate simulation of traveling acoustic streaming,and also preliminaryly studies the acoustic streaming in standing waves and the particle driving problem.