Generalised Jeffery's equations for rapidly spinning particles. Part 2. Helicoidal objects with chirality

Journal of Fluid Mechanics, Journal Year: 2024, Volume and Issue: 979

Published: Jan. 9, 2024

In this two-part study, we investigate the motion of rigid, active objects in shear Stokes flow, focusing on bodies that induce rapid rotation as part their activity. Part 2, derive and analyse governing equations for rapidly spinning complex-shaped particles – general helicoidal with chirality. Using multiscale framework develop 1 (Dalwadi et al. , J. Fluid Mech. vol. 979, 2024, A1), systematically emergent angular translational dynamics these chiral objects. We show due to can be described by effective generalised Jeffery's equations, which differ from classic versions via inclusion additional terms account chirality other asymmetries. Furthermore, use our analytic results characterise quantify explicit effect hydrodynamic shape objects, expanding significantly scope seminal study.

Language: Английский

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Buoyancy–flow coupled dispersion of active spheroids in a vertical pipe: effects of elongation and settling

Journal of Fluid Mechanics, Journal Year: 2025, Volume and Issue: 1007

Published: March 24, 2025

Many particles, whether passive or active, possess elongated shapes. When these particles settle swim in shear flows, they often form regions of accumulation and depletion. Additionally, the density contrast between fluid can further alter flow by increasing local suspension density, resulting a two-way buoyancy–flow coupling mechanism. This study investigates coupled dispersion active spheroids, examining effects elongation, orientation-dependent settling gyrotaxis vertical pipe subjected to either downwards upwards discharge. While concentration velocity profiles spheroids spherical gyrotactic swimmers be analysed similarly recent study, notable differences characteristics emerge due different streamline-crossing mechanisms. For suspensions swimmers, interplay settling, gyrotaxis-induced shear-induced trapping results distinct distributions compared those neutrally buoyant extremely dilute with negligible effect. These impact drift velocity, dispersivity, time elapsed steady under varying rates. Interestingly, low-shear non-settling around centreline, commonly observed planar Poiseuille flow, is absent change confinement from reflectional rotational symmetry. However, show non-trivial response strong downwelling phenomenon, linked centreline bears similarities flow.

Language: Английский

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Rapidly yawing spheroids in viscous shear flow: emergent loss of symmetry

Journal of Fluid Mechanics, Journal Year: 2025, Volume and Issue: 1009

Published: April 15, 2025

We investigate the emergent three-dimensional (3-D) dynamics of a rapidly yawing spheroidal swimmer interacting with viscous shear flow. show that rapid generates non-axisymmetric effects, active behaving as an effective passive particle two orthogonal planes symmetry. also demonstrate this asymmetry generated by can cause chaotic behaviour in dynamics, stark contrast to rotating spheroids, which are equivalent those spheroids. In general, we find shape under is different average particle. Moreover, despite having symmetry, not ellipsoid except for specific scenarios spheroid. these scenarios, calculate analytically aspect ratio use multiple scales analysis systems derive behaviour, requires solving non-autonomous nonlinear 3-D dynamical system, and validate our via comparison numerical simulations.

Language: Английский

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Hydrodynamics of Active Colloids

Royal Society of Chemistry eBooks, Journal Year: 2024, Volume and Issue: unknown, P. 412 - 450

Published: Dec. 20, 2024

An active particle moving in a liquid medium will generate flows that extend into the surrounding medium. These particle-generated couple particles to each other and any bounding surfaces or interfaces. Active hydrodynamic interactions are implicated trapping of by solid surfaces, clustering phase separation, topics current interest colloids community. In this chapter, we review colloidal hydrodynamics, starting from foundational concepts Stokes flow, introducing some necessary mathematical formalism. We then cover hydrodynamics interfacially-driven microswimmers, including how model flow field sourced self-phoretic colloid. The latter part chapter focuses on developing theory fundamental singularities as these can provide analytically tractable approximations for colloid/colloid colloid/surface interactions. close with two outlooks applications developed research.

Language: Английский

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Unveiling memory-driven dynamics: Fractional calculus and microswimmer trajectories in 1D shear flow

International Journal of Non-Linear Mechanics, Journal Year: 2024, Volume and Issue: unknown, P. 105005 - 105005

Published: Dec. 1, 2024

Language: Английский

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