Numerical study of the influence of magnetic field and throughflow on the onset of thermo-bio-convection in a Forchheimer‑extended Darcy-Brinkman porous nanofluid layer containing gyrotactic microorganisms

This paper accommodates numerical investigation on the onset of magneto-thermo-bioconvection in nanofluid suspension of gyrotactic microbes saturated in a porous medium under the imposition of vertical throughflow and quadratic drag. The modified Darcy-Brinkman-Forchheimer model is utilized to drive the governing equations. The normal mode technique along with linear stability analysis is imposed to establish the agitated system of equations. An eight-order Galerkin methodology is utilized to numerically extract the critical thermal Rayleigh number values from the tedious eigenvalue problem. The power of vertical throughflow and quadratic drag is perceived to enhance the thermal energy transfer and stabilize the nanofluid suspension that consequently tries to restrict the convective process. The intensity of the magnetic field is identified to delay the onset of magneto-thermo-bioconvection. It is also found that the presence of fast-moving gyrotactic microorganisms and top-heavy nanofluid concentration form an unstable system to accelerate the beginning of the magneto-thermo-bioconvection. The outcome of this work may find applications in microfluidic devices, enhanced oil recovery, and many other areas for controlling the speed of the convective process.