Study On The Motion Mechanism Of The Suspended Slip Particle Based On Lattice Boltzmann Method

The flow problem of suspended slip particles exists in important fundamental fields such as biomedicine,Micro-Electro-Mechanical Systems and microfluidics,and has been widely used in precise control of drug particles and particles sorting in microfluidic systems.The interaction between the suspended slip particles and the fluid is more complex than the conventional particle-fluid system due to the slip effect between the flow and the solid.The lattice Boltzmann method is easy to handle complex fluid-solid boundaries and has high computational efficiency due to its mesoscopic properties,and has greater advantages in studying the flow of suspended slip particles.In this paper,the lattice Boltzmann method is used to study the lateral migration mechanism of the suspended slip particle in the channel and the motion law of the suspended slip particle in the cavity,which is mainly as follows:(1)The lateral migration mechanism of the suspended slip particle in twodimensional channels is numerically investigated.The effects of initial position,slip length,particle Reynolds number and blockage ratio on the lateral migration of the suspended slip particle were analyzed.Numerical results show that due to the slip effect,unlike the lateral motion of the conventional particle,there are two equilibrium positions of the suspended slip particle in the channel,and increasing the slip length will bring the equilibrium position of the suspended slip particle closer to the wall.The lateral motion trajectory of the suspended slip particle at different locations is affected by the slip length,and the response of the suspended slip particle near the wall to the change in slip length is more pronounced due to the velocity distribution characteristics of the channel Poiseuille flow.As the Reynolds number of particle increases,the equilibrium position of the lateral migration of the suspended slip particle is closer to the wall,while the increase of the blockage ratio makes the velocity of the suspended slip particle decrease and the equilibrium position of the lateral migration moves toward the centerline of the channel.(2)The motion mechanism of the suspended slip particle in a two-dimensional cavity is numerically investigated.The effects of slip length,initial position,Reynolds number and particle size on the particle limit cycle motion were analyzed.The results show that as the slip length of the suspended slip particle increases,the trajectory of the particle after stabilization(limit cycle)is closer to the cavity wall.And the suspended slip particle in steady periodic motion is subjected to alternating effects of drag reduction and drag increase.The initial position has no effect on the trajectory of the suspended slip particle.And as the cavity Reynolds number increases,the suspended slip particle is influenced by primary and secondary vortices in the cavity and the flow of these can be more complex.In addition,as particle size increases,the suspended slip particle can move towards the wall influenced by the lubrication force and the limit cycle will contract towards the center of the cavity.As the influence of slip length and particle size on the motion of the suspended slip particle is mutually constrained,it helps to achieve trajectory prediction and trajectory control of the suspended slip particle.