A neutrally buoyant particle motion in a double-lid-driven square cavity

A neutrally buoyant circular particle motion in a double lid-driven cavity flow (LDCF) is investigated by immersed moving boundary based lattice Boltzmann method, where the top and bottom walls move with constant velocities. To understand the mechanism of particle motion in double LDCF, the influence of the moving wall velocity ratio u_wr, initial position, particle size, and Reynolds number on the trajectory and limit circle of the neutrally buoyant circular particle motion in double LDCF is systematically studied. The results show that the trajectory of the particle is obviously different with different afore impactors. As u_wr varies, the limit circle is changed accordingly. The limit circle of the particle motion is insensitive to the initial position with negative moving wall velocity ratio except for the initial location of the particle at the center of the cavity with u_wr= -1, where the particle is stationary all the time. When moving wall velocity ratio becomes positive, due to the more complex fluid structure or vortices in cavity, some interesting limit circle modes of particle motion are observed. When particle size increases, the confinement of cavity is enhanced. The limit circle shrinks to the center of the cavity, and it can be greatly changed with different particle size for u_wr>0. With the increment of Reynolds number, the flow is strengthened, and the influence domain and the strength of the secondary vortices are enhanced, where the limit circle of particle motion is pushed away from the secondary vortices generated in cavity. However, the limit circle mode of particle motion is insensitive to the Reynolds number varied from 500 to 5000.