Numerical investigation of falling bacterial plumes caused by bioconvection in a three-dimensional chamber

Hyun Geun Lee, Junseok Kim

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Oxytactic bacteria like Bacillus subtilis are denser than water and swim up an oxygen gradient as they require certain minimum concentration of oxygen to be active. Due to upswimming, bacteria accumulate in a layer below the water surface and the density of an initially uniform suspension becomes greater near the water surface than the water bottom. When the upper bacteria-rich boundary layer is too dense, it becomes unstable and an overturning instability develops, leading to the formation of falling bacterial plumes. Bioconvection in modestly diluted cell suspensions is described by equations for concentrations of bacteria and oxygen together with the Navier-Stokes equations and the continuity equation. In this paper, we investigate numerically falling bacterial plumes caused by bioconvection in a three-dimensional chamber by solving the full chemotaxis-fluid coupled system. In numerical simulations of the system, the admissible time step is restricted by stability criteria due to a high Schmidt number, which corresponds to highly viscous fluids or low diffusion rates of bacteria. In order to avoid a too strong restriction on the time step, we use an operator splitting-type Navier-Stokes solver: the advection term is solved using a semi-Lagrangian method and the diffusion term is solved using the backward Euler method. We present numerical examples showing the formation of falling bacterial plumes out of random initial data and the convergence towards stationary bacterial plumes. And the merging of neighboring plumes is observed for a specific parameter set.

Original languageEnglish
Pages (from-to)120-130
Number of pages11
JournalEuropean Journal of Mechanics, B/Fluids
Volume52
DOIs
Publication statusPublished - 2015 Jul 1

Fingerprint

Numerical Investigation
falling
Bacteria
bacteria
plumes
chambers
Three-dimensional
Water
Oxygen
surface water
oxygen
Semi-Lagrangian Method
Backward Euler Method
Schmidt number
Operator Splitting
Chemotaxis
Bacillus
Continuity Equation
continuity equation
viscous fluids

Keywords

  • Bioconvection
  • Coupled chemotaxis-fluid model
  • Finite difference method
  • Oxytactic bacteria

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Mathematical Physics

Cite this

Numerical investigation of falling bacterial plumes caused by bioconvection in a three-dimensional chamber. / Lee, Hyun Geun; Kim, Junseok.

In: European Journal of Mechanics, B/Fluids, Vol. 52, 01.07.2015, p. 120-130.

Research output: Contribution to journalArticle

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