Foundation and challenges in modelling dilute active suspensions
File(s)
Published version
Author(s)
Fung, Lloyd
Caldag, Hakan Osman
Bees, Martin
Type
Journal Article
Abstract
Active suspensions, which consist of suspended self-propelling particles such as swimming microorganisms, often exhibit non-trivial transport properties. Continuum models are frequently employed to elucidate phenomena in active suspensions, such as shear trapping of bacteria, bacterial turbulence and bioconvection patterns in suspensions of algae. Yet, these models are often empirically derived and may not always agree with the individual-based description of active particles. Here we review the essential coarse-graining steps to develop commonly used continuum models from their respective microscopic dynamics. All the assumptions needed to reach popular continuum models from a multi-particle Fokker–Planck equation, which governs the probability of the full configuration space, are explicitly presented. In the dilute limit, this approach leads to the mean-field model (a.k.a. Doi–Saintillan–Shelley model), which can be further reduced to a continuum equation for particle density. Moreover, we review the limitations and highlight the challenges related to continuum descriptions, including significant issues in implementing physical boundary conditions and the possible emergence of singular solutions.
This article is part of the theme issue ‘Biological fluid dynamics: emerging directions’.
This article is part of the theme issue ‘Biological fluid dynamics: emerging directions’.
Date Issued
2025-09-11
Date Acceptance
2025-04-14
Citation
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2025, 383 (2304)
ISSN
1364-503X
Publisher
The Royal Society
Journal / Book Title
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume
383
Issue
2304
Copyright Statement
© 2025 The Authors. Published by the Royal Society under the terms of theCreativeCommonsAttribution Licensehttp://creativecommons.org/licenses/ by/4.0/, which permits unrestricted use, provided the original author and source are credited.
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/40931659
Subjects
active Brownian particles
BACTERIAL
biologically active suspensions
continuum model
EQUATIONS
FLUID-DYNAMICS
GENERALIZED TAYLOR DISPERSION
GYROTACTIC SWIMMING MICROORGANISMS
HYDRODYNAMICS
MECHANICS
microswimmers
MOTION
Multidisciplinary Sciences
ORIENTATION
RIGID PARTICLES
Science & Technology
Science & Technology - Other Topics
Publication Status
Published
Coverage Spatial
England
Article Number
20240251
Date Publish Online
2025-09-11