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

• 作者: Faris Alzahranit M.Ferdows Nayema Islam Nima O.Anwar Beg S.Kuharatt
• 来源期刊: 生物数学学报:英文版
• 学科: 工学
• 关键词: BIOCONVECTION gyrotactic microorganisms oxygen diffusion BUOYANCY Lewis number boundary layers fuel cells numerical solution Nusselt nurnber Sherwood number
• 年，卷（期）: 2020,（4）
• 页码范围: 141-165
• 页数: 25页
• 分类号: TG6

摘要

Bioconvection has shown significant promise for environmentally friendly,sustainable“green”fuel cell technologies.The improved design of such systems requires continuous refinements in biomatheatical modeling in conjunction with laboratory and fieldtesting.Motivated by exploring deeper the near-wall transport phenomena involved inbio-inspired fuel cells,in the present paper,we examine analytically and numericallythe combined free-forced convective steady boundary layer flow from a solid verticalflat plate embedded in a Darcian porous medium containing gyrotactic microorganisms.Gyrotaxis is one of the many taxes exhibited in biological microscale transport,andother examples include magneto-taxis,photo-taxis,chemotaxis and geo-taxis (reflecting the response of microorganisms to magnetic field,light,chemical concentration orgravity,respectively). The bioconvection fuel cell also contains difusing oxygen specicswhich mimics the cathodic behavior in a proton exchange membrane(PEM) systei.Thevertical wall is maintained at isosolutal (constant oxygen volume fraction and motilemicroorganism density) and iso-thermal conditions. Wall values of these quantities aresustained at higher values than the ambient temperature and concentration of oxygenand biological microorganism specics.Similarity transformations are applied to renderthe governing partial differential equations for mass,momentum,energy,oxygen speciesand microorganism species density into a system of ordinary differential equations. Theemerging eight order nonlinear coupled,ordinary differential boundary value problemfeatures several important dimensionless control parameters,namely Lewis number(Le),buoyancy ratio paraneter i.e. ratio of oxygen species buoyancy force to thermal buoy-ancy force(Nr), bioconvection Rayleigh number(Rb), bioconvection Lewis number(Lb),bioconvection Peclet number(Pe) and the mixed convection parameter(e) spanning theentire range of free and forced convection. The transformed nonlinear system of equationswith boundary conditions is