"Bioconvection Patterns" in Cultures of Free-Swimming Organisms

Platt, John R.

doi:10.1126/science.133.3466.1766

Cited by 354 publications

(159 citation statements)

References 4 publications

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“…[15,41,42]. However, the instability reported herein for magnetotactic bacteria lacks a key ingredient usually involved in the previously mentioned phenomenology.…”

Section: Discussion: Challenging Theoriesmentioning

confidence: 77%

Destabilization of a flow focused suspension of magnetotactic bacteria

et al. 2016

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Active matter is a new class of intrinsically out-of equilibrium material with intriguing properties. The recent upsurge of studies in this field has mostly focused on the spontaneous behavior of these systems. Yet, many systems evolve under external constraints and driving forces, being subjected to both flow and various taxis. We present a new experimental system based on the directional control of magnetotactic bacteria which enables quantitative investigations to complement the challenging theoretical description of such systems. We explore the behavior of self-propelled magnetotactic bacteria as a particularly rich and versatile class of driven matter, whose behavior can be studied under a range of hydrodynamic and magnetic field stimuli. In particular we demonstrate that the competition between cell orientation toward a magnetic field and hydrodynamic flow lead not only to jetting, but to a new pearling instability. This model system illustrates new structuring capabilities of driven active matter.

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“…[15,41,42]. However, the instability reported herein for magnetotactic bacteria lacks a key ingredient usually involved in the previously mentioned phenomenology.…”

Section: Discussion: Challenging Theoriesmentioning

confidence: 77%

Destabilization of a flow focused suspension of magnetotactic bacteria

et al. 2016

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“…Direct thermal convection can occur in micro-organism suspensions if the containing chamber is heated from below or from the sides, or if sufficient heat is absorbed from the illumination. However, bioconvection continues in a layer that is strongly cooled from below, so it is not a thermal effect (Platt, 1961). The radius, a, of a typical gyrotactic cell is approximately 5 × 10 −4 cm and the specific gravity is approximately 0.05.…”

Section: Introductionmentioning

confidence: 99%

Wavelengths of Gyrotactic Plumes in Bioconvection

Ghorai

Hill

2000

Bulletin of Mathematical Biology

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Bioconvection occurs as the result of the collective behaviour of many microorganisms swimming in a fluid and is realized as patterns similar to those of thermal convection which occur when a layer of fluid is heated from below. We consider the phenomenon of pattern formation due to gyrotaxis, an orientation mechanism which results from the balance of gravitational and viscous torques acting on bottom-heavy micro-organisms. The continuum model of Pedley et al. (1988, J. Fluid. Mech. 195, 223-237) is used to describe the suspension. The system is governed by the Navier-Stokes equations for an incompressible fluid coupled with a micro-organism conservation equation. These equations are solved numerically using a conservative finite-difference scheme. To examine the dependence of the horizontal pattern wavelengths on the parameters, we consider two-dimensional solutions in a wide chamber using rigid side walls. The wavelengths of the numerical computations are in good agreement with the experimental observations and we provide the first computational examples of the commonly seen 'bottom-standing' plumes.

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“…Classical studies in bioconvection were largely mobilized by Platt (1961) who examined bioconvection patterns in cultures of free swimming organism and concluded that the moving polygonal patterns in Tetrahymena, ciliates and flagellates cultures which resemble Benard cells are not due to thermal convection but generated as a result of a dynamic instability due tointernal and mechanical energy input. Much later, Xu (2015) used Lie group analysis to investigate bioconvection flow of a nanofluid in a power law streaming flow.…”

Section: Introductionmentioning

confidence: 99%

Numerical solutions for gyrotactic bioconvection in nanofluid-saturated porous media with Stefan blowing and multiple slip effects

Uddin¹,

Alginahi²,

Bég³

et al. 2016

Computers & Mathematics with Applications

123

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Abstract:A mathematical model is developed to examine the effects of the Stefan blowing, second order velocity slip, thermal slip and microorganism species slip on nonlinear bioconvection boundary layer flow of a nanofluid over a horizontal plate embedded in a porous medium with the presence of passively controlled boundary condition. Scaling group transformations are used to find similarity equations of such nanobioconvection flows. The similarity equations are numerically solved with a Chebyshev collocation method. Validation of solutions is conducted with a Nakamura tri-diagonal finite difference algorithm. The effects of nanofluid characteristics and boundary properties such as the slips, Stefan blowing, Brownian motion and Grashof number on the dimensionless fluid velocity, temperature, nanoparticle volume fraction, motile microorganism, skin friction, the rate of heat transfer and the rate of motile microorganism transfer are investigated. The work is relevant to bio-inspired nanofluidenhanced fuel cells and nano-materials fabrication processes.

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"Bioconvection Patterns" in Cultures of Free-Swimming Organisms

Cited by 354 publications

References 4 publications

Destabilization of a flow focused suspension of magnetotactic bacteria

Destabilization of a flow focused suspension of magnetotactic bacteria

Wavelengths of Gyrotactic Plumes in Bioconvection

Numerical solutions for gyrotactic bioconvection in nanofluid-saturated porous media with Stefan blowing and multiple slip effects

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