Different particle-accumulation structures arising from particle–boundary interactions in a liquid bridge

The formation of particle-accumulation structures in the flow in a cylindrical liquid bridge driven by the thermocapillary effect is studied. The problem is modeled as an incompressible fluid seeded with a low concentration of small spherical particles which are assumed to have a negligible effect on the flow. The particle motion is modeled by pure advection except for small regions at the free surface and walls where the particle interaction with the free surface and walls is modeled by a hard-wall potential which restricts the motion of the particle within some interaction length from the boundaries. The model yields a wide range of particle-accumulation structures when varying the relative interaction length from 5 × 10 - 3 to 3 × 10 - 2 . It is found that in many cases each particle need undergo no more than a handful of returns to the free surface for particle-accumulation structures to arise. It is also found that the shape of the particle-accumulation structures changes qualitatively at certain critical interaction lengths.