Sedimentation and structure of squirmer suspensions under gravity

Fuente: arXiv
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Main Authors: G., C. Miguel Barriuso, Serna, Horacio, Pagonabarraga, Ignacio, Valeriani, Chantal
Format: Preprint
Published: 2024
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author G., C. Miguel Barriuso
Serna, Horacio
Pagonabarraga, Ignacio
Valeriani, Chantal
author_facet G., C. Miguel Barriuso
Serna, Horacio
Pagonabarraga, Ignacio
Valeriani, Chantal
contents The effect of gravity on the collective motion of living microswimmers, such as bacteria and micro-algae, is pivotal to unravel not only bio-convection patterns but also the settling of bacterial biofilms on solid surfaces. In this work, we investigate suspensions of microswimmers under the influence of a gravitational field and hydrodynamics, simulated via dissipative particle dynamics (DPD) coarse-grained model. We first study the collective sedimentation of passive colloids and microswimmers of the puller and pusher types upon increasing the imposed gravitational field and compare with previous results. Once sedimentation occurs, we observe that, as the gravitational field increases, the bottom layer undergoes a transition to an ordered state compatible with a hexagonal crystal. In comparison with passive colloids, both pullers and pushers easily rearrange at the bottom layer to anneal defects. Specifically, pullers are better than pushers in preserving the hexagonal order of the bottom mono-layer at high gravitational fields.
format Preprint
id arxiv_https___arxiv_org_abs_2411_13359
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Sedimentation and structure of squirmer suspensions under gravity
G., C. Miguel Barriuso
Serna, Horacio
Pagonabarraga, Ignacio
Valeriani, Chantal
Soft Condensed Matter
The effect of gravity on the collective motion of living microswimmers, such as bacteria and micro-algae, is pivotal to unravel not only bio-convection patterns but also the settling of bacterial biofilms on solid surfaces. In this work, we investigate suspensions of microswimmers under the influence of a gravitational field and hydrodynamics, simulated via dissipative particle dynamics (DPD) coarse-grained model. We first study the collective sedimentation of passive colloids and microswimmers of the puller and pusher types upon increasing the imposed gravitational field and compare with previous results. Once sedimentation occurs, we observe that, as the gravitational field increases, the bottom layer undergoes a transition to an ordered state compatible with a hexagonal crystal. In comparison with passive colloids, both pullers and pushers easily rearrange at the bottom layer to anneal defects. Specifically, pullers are better than pushers in preserving the hexagonal order of the bottom mono-layer at high gravitational fields.
title Sedimentation and structure of squirmer suspensions under gravity
topic Soft Condensed Matter
url https://arxiv.org/abs/2411.13359