Dispersion of gyrotactic micro-organisms in pipe flows

Jiang, Weiquan; Chen, Guoqian

doi:10.1017/jfm.2020.91

Cited by 29 publications

(69 citation statements)

References 73 publications

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“…2011; Volpe et al. 2014; Jiang & Chen 2019 a , 2020), Thus, it requires that both the incident swimming probability flux and the incident translational-diffusion probability flux through the walls are balanced by their corresponding reflective fluxes. Namely, ensuring the conservation of particles in the phase space.…”

Section: Formulation Of Transport Problemmentioning

confidence: 99%

“…2011). Recently, Jiang & Chen (2019 a , 2020) constructed a more integrated average approach also based on the GTD theory and analytically derived the overall drift and dispersivity for very dilute suspensions. This method gets rid of the separate-length-scale requirement of the P–K and GTD models, and thus is adaptable for wide applications.…”

Section: Introductionmentioning

confidence: 99%

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Transient dispersion process of active particles

Jiang

Chen

2021

J. Fluid Mech.

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Active particles often swim in confined environments. The transport mechanisms, especially the global one as reflected by the Taylor dispersion model, are of great practical interest to various applications. For the active dispersion process in confined flows, previous analytical studies focused on the long-time asymptotic values of dispersion characteristics. Only several numerical studies preliminarily investigated the temporal evolution. Extending recent studies of Jiang & Chen (J. Fluid Mech., vol. 877, 2019, pp. 1–34; vol. 899, 2020, A18), this work makes a semi-analytical attempt to investigate the transient process. The temporal evolution of the local distribution in the confined-section–orientation space, drift, dispersivity and skewness, is explored based on moments of distributions. We introduce the biorthogonal expansion method for solutions because the classic integral transform method for passive transport problems is not applicable due to the self-propulsion effect. Two types of boundary condition, the reflective condition and the Robin condition for wall accumulation, are imposed respectively. A detailed study on spherical and ellipsoidal swimmers dispersing in a plane Poiseuille flow demonstrates the influences of the swimming, shear flow, initial condition, wall accumulation and particle shape on the transient dispersion process. The swimming-induced diffusion makes the local distribution reach its equilibrium state faster than that of passive particles. Although the wall accumulation significantly affects the evolution of the local distribution and the drift, the time scale to reach the Taylor regime is not obviously changed. The shear-induced alignment of ellipsoidal particles can enlarge the dispersivity but impacts slightly on the drift and the skewness.

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Section: Formulation Of Transport Problemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transient dispersion process of active particles

Jiang

Chen

2021

J. Fluid Mech.

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“…Importantly, a recent numerical study by Croze et al (2013) further showed that the GTD model provides a much more accurate prediction for the cell distribution obtained from individual-based simulation than the one by Pedley & Kessler (1990) especially when the shear (or vorticity) rate of the surrounding flow is high. Recently, Jiang & Chen (2020) have also demonstrated the superiority of the GTD model without making any approximation to the Smoluchowski equation. This observation was further supported by the recent experimental result in Croze, Bearon & Bees (2017).…”

Section: Introductionmentioning

confidence: 99%

Bifurcation and stability of downflowing gyrotactic micro-organism suspensions in a vertical pipe

2020

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“…While there are many studies of how low numbers of swimmers interact within a pressure gradient, there are relatively few investigations of how the activity-driven and pressure-driven flows will interact in a dense continuum of swimmers. A number of authors have considered models of dilute suspension of active swimmers in a pressure gradient [25][26][27] and dense continuum models of channel flow, albeit in a tumbling nematic regime [28]. Others have reported experimental studies of similar systems [29], while there are also general reviews of the rheology of active fluids in [13,30,31].…”

Section: Introductionmentioning

confidence: 99%

Pressure-driven changes to spontaneous flow in active nematic liquid crystals

et al. 2020

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We consider the effects of a pressure gradient on the spontaneous flow of an active nematic liquid crystal in a channel, subject to planar anchoring and no-slip conditions on the boundaries of the channel. We employ a model based on the Ericksen-Leslie theory of nematics, with an additional active stress accounting for the activity of the fluid. By directly solving the flow equation, we consider an asymptotic solution for the director angle equation for large activity parameter values and predict the possible values of the director angle in the bulk of the channel. Through a numerical solution of the full nonlinear equations, we examine the effects of pressure on the branches of stable and unstable equilibria, some of which are disconnected from the no-flow state. In the absence of a pressure gradient, solutions are either symmetric or antisymmetric about the channel midpoint; these symmetries are changed by the pressure gradient. Considering the activity-pressure state space allows us to predict qualitatively the extent of each solution type and to show, for large enough pressure gradients, that a branch of non-trivial director angle solutions exists for all activity values.

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Dispersion of gyrotactic micro-organisms in pipe flows

Cited by 29 publications

References 73 publications

Transient dispersion process of active particles

Transient dispersion process of active particles

Bifurcation and stability of downflowing gyrotactic micro-organism suspensions in a vertical pipe

Pressure-driven changes to spontaneous flow in active nematic liquid crystals

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