Research On Particles Sedimentation And Their Migration In Serpentine Channels

Sedimentation and migration of particles are not only ubiquitous in nature,but also in a wide range of industrial production background,which have always been a classic problem in fluid mechanics.In this paper,the lattice Boltzmann method based on momentum exchange is applied to direct numerical simulation towards above two models.The main research work and results are summarized as follows:(1)For the particle Reynolds number range of 5 ? Re ? 12,two particles' deposition is calculated.It is mainly concerned with the influence of the density difference between particles k on its periodic vibration.The settlement characteristics of the Reynolds number can be divided into three stages: when the Re is smaller,the transverse vibration amplitude of the particles decreases with the increase of k,which is the opposite when the Re is larger.There is a critical Reynolds number in the middle of the two situations,and in the vicinity of the Reynolds number,the settlement of the particles has the above two characteristics.In addition,the stable settlement structure of two particles and the conditions for the heavy particles to get rid of the light particles are also studied.(2)For the channel Reynolds number range of 20 ? Re ? 120,the single particle in the serpentine channel is simulated.The effects of the Reynolds number,particle density as well as the initial particle position are taken into account.Numerical results include the streamlines,particle trajectories,final equilibrium positions and the time it takes to travel in the channel.It has been found that the particle is likely to migrate to a similar equilibrium position irrespective of its initial position when Re is large.Furthermore,there exists a critical solid-to-fluid density ratio for which the particle travels fastest in the channel.(3)Under the same conditions,2,8 and 16 particles are simulated directly in the serpentine channel.The influence of the channel Reynolds number,the number of particles and the initial position distribution of the particles is emphatically studied.When the number of particles is 2,no matter what the value of initial position is,the larger the Reynolds number is,the larger the distance between the particle and the wall located on the upper side of the center-line.In addition,the velocity of the particle migration on the lower side is greater than that of the upper side.When the numbers of particles are 8 and 16,the larger the Reynolds number,the moving trajectories of the particles with the initial position on the same side of the center-line are closer to a curve.