Biomathematical model for gyrotactic free-forced bioconvection with oxygen diffusion in near-wall transport within a porous medium fuel cell

Nima, NI, Ferdows, M, Beg, OA ORCID: https://orcid.org/0000-0001-5925-6711, Kuharat, S and Alzahrani, F 2020, 'Biomathematical model for gyrotactic free-forced bioconvection with oxygen diffusion in near-wall transport within a porous medium fuel cell' , International Journal of Biomathematics .

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Abstract

Bioconvection has shown significant promise for environmentally friendly, sustainable “green” fuel cell technologies. The improved design of such systems requires continuous refinements in biomathematical modelling in conjunction with laboratory and field testing. Motivated by exploring deeper the near-wall transport phenomena involved in bioinspired fuel cells, in the present article, we examine analytically and numerically the combined free-forced convective steady boundary layer flow from a solid vertical flat plate embedded in a Darcian porous medium containing gyrotactic microorganisms. Gyrotaxis is one of many taxes exhibited in biological microscale transport, and other examples include magneto-taxis, photo-taxis, chemotaxis and geo-taxis (reflecting the response of micro-organisms to magnetic field, light, chemical concentration or gravity, respectively). The bioconvection fuel cell also contains diffusing oxygen species which mimics the cathodic behavior in a proton membrane exchange (PEM) system. The vertical wall is maintained at iso-solutal (constant oxygen volume fraction and motile micro-organism density) and iso-thermal conditions. Wall values of these quantities are sustained at higher values than the ambient temperature and concentration of oxygen and biological micro-organism species. Similarity transformations are applied to render the governing partial differential equations for mass, momentum, energy, oxygen species and micro-organism species density into a system of ordinary differential equations. The emerging eight order nonlinear coupled, ordinary differential boundary value problem features several important dimensionless control parameters, namely Lewis number (Le), buoyancy ratio parameter i.e. ratio of oxygen species buoyancy force to thermal buoyancy force (Nr), bioconvection Rayleigh number (Rb), bioconvection Lewis number (Lb), bioconvection Péclet number (Pe) and the mixed convection parameter spanning the entire range of free and forced convection. The transformed non-linear system of equations with boundary conditions is solved numerically by a finite difference method with central differencing, tridiagonal matrix manipulation and an iterative procedure. Computations are validated with the symbolic Maple 14.0 software. The influence of buoyancy and bioconvection parameters on the dimensionless temperature, velocity, oxygen concentration and motile microorganism density distribution, Nusselt, Sherwood and gradient of motile microorganism density are studied. The work clearly shows the benefit of utilizing biological organisms in fuel cell design and presents a logical biomathematical modelling framework for simulating such systems. In particular, the deployment of gyrotactic micro-organisms is shown to stimulate improved transport characteristics in heat and momentum at the fuel cell wall.

Item Type: Article
Schools: Schools > School of Computing, Science and Engineering
Journal or Publication Title: International Journal of Biomathematics
Publisher: World Scientific
ISSN: 1793-5245
Related URLs:
Depositing User: OA Beg
Date Deposited: 24 Feb 2020 09:44
Last Modified: 30 Apr 2020 08:30
URI: http://usir.salford.ac.uk/id/eprint/56495

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