Thermomagnetic Bioconvection Flow in a Semitrapezoidal Enclosure Filled With a Porous Medium Containing Oxytactic Micro-Organisms: Modeling Hybrid Magnetic Biofuel Cells

Abstract Hybrid fuel cells are becoming increasingly popular in 21st century energy systems engineering. These systems combine multiple features including various geometries, electromagnetic fluids, bacteria (micro-organisms), thermosolutal convection, and porous media. Motivated by these developments in the present work, we simulate the two-dimensional magnetohydrodynamic (MHD) natural triple convection flow in a semitrapezoidal enclosure saturated with electrically conducting water containing oxytactic micro-organisms and oxygen species. The Darcy–Brinkman model is deployed for porous media drag effects. The primitive governing partial differential conservation equations for mass, momentum, energy, oxygen species, and motile micro-organism species density are transformed using a vorticity–stream function formulation and nondimensional variables into a nonlinear boundary value problem. A numerical solution is obtained using a finite difference method with incremental time steps. The mathematical model features a number of controlling parameters, i.e., Prandtl number, Rayleigh number, bioconvective Rayleigh number, Darcy parameter, Hartmann (magnetic body force) number, Lewis number, Péclet number, oxygen diffusion ratio, and fraction of consumption oxygen to diffusion of oxygen parameter. Transport characteristics (streamlines, isotherms, oxygen isoconcentration, and motile micro-organism concentration) are computed for several of these parameters. Micro-organisms’ impact on the rate of heat transfer at the boundaries is found to be beneficial or destructive, depending on combination of other parameters in the simulations. Additionally, Nusselt number and oxygen species Sherwood number are computed at the hot vertical wall. The simulations are relevant to hybrid electromagnetic microbial fuel cells.