Sedimentation of two spheres in a square tube

Abstract

In this study, we simulated the sedimentation of two identical spheres having the same density in a square tube. Compared with the center-line and the diagonal planes (including the reverse diagonal plane), the sedimentation of spheres on other planes is more complicated. Results show that at relatively low and high Reynolds number, the spheres will deflect and eventually move to the diagonal plane of the square tube. At the medium Reynolds number, the spheres settle near the initial plane. The possible mechanisms underlying these behaviors are examined. Finally, it is shown that the distance between the spheres increases with an increase in the Reynolds number, which is applicable to all the initial settlement planes studied.

Motion characteristics of squirmers in linear shear flow

“…In this work, the improved bounce-back scheme proposed by Lallemand and Luo (2003) was used, and after improvement, this interpolationbased bounce-back scheme is stable, robust, and easy to implement in simulations. Note that a similar scheme was used in our earlier research (Guan et al 2022(Guan et al , 2021. The improved bounce-back scheme is shown in figure 3, where solid squares indicate solid nodes inside the curved boundary, solid circles indicate fluid nodes outside the curved boundary, and hollow triangles indicate boundary nodes where the bounce-back occurs.…”