## Abstract

Particle-resolved, three-dimensional, time-dependent simulations of rigid and flexible cylinders fluidized by

a liquid flow in fully periodic domains have been performed by means of the lattice-Boltzmann method supplemented with immersed boundaries. The solids volume fraction ranges from 0.10 to 0.48 and the length-over-diameter aspect ratio of the cylinders from 4 to 12. The bending stiffness of the cylinders is the

third major input parameter. The resulting Reynolds numbers based on the average slip velocity of the

cylinders and their equivalent diameter range from 6 to 70. It is shown that increasing the flexibility – that is, decreasing the bending stiffness – reduces the Reynolds number, an effect that is most pronounced for low solids volume fractions and long cylinders. As for rigid cylinders, the distribution of orientations relative to the direction of gravity of flexible cylinders is a pronounced function of the solids volume fraction and the aspect ratio. Flexibility tends to somewhat randomize the orientation distribution which could explain the

effect of flexibility on the slip velocity and thus the Reynolds number.

a liquid flow in fully periodic domains have been performed by means of the lattice-Boltzmann method supplemented with immersed boundaries. The solids volume fraction ranges from 0.10 to 0.48 and the length-over-diameter aspect ratio of the cylinders from 4 to 12. The bending stiffness of the cylinders is the

third major input parameter. The resulting Reynolds numbers based on the average slip velocity of the

cylinders and their equivalent diameter range from 6 to 70. It is shown that increasing the flexibility – that is, decreasing the bending stiffness – reduces the Reynolds number, an effect that is most pronounced for low solids volume fractions and long cylinders. As for rigid cylinders, the distribution of orientations relative to the direction of gravity of flexible cylinders is a pronounced function of the solids volume fraction and the aspect ratio. Flexibility tends to somewhat randomize the orientation distribution which could explain the

effect of flexibility on the slip velocity and thus the Reynolds number.

Original language | English |
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Journal | Acta Mechanica |

Publication status | Accepted/In press - 8 Sep 2020 |

## Keywords

- Fluidization
- particle-resolved simulation
- non-spherical particles
- flexible fibers
- lattice-Boltzmann method