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The water-based bioconvection of a nanofluid containing motile gyrotactic micro-organisms (moves under the effects of gravity) over a nonlinear inclined stretching sheet in the presence of a nonuniform magnetic field has been investigated. This regime is encountered in the bio-nanomaterial electroconductive polymeric processing systems currently being considered for third-generation organic solar coatings, anti-fouling marine coatings, etc. Oberbeck–Boussinesq approximation along with ohmic dissipation (Joule heating) is considered in the problem. The governing equations of the flow are nonlinear partial differential equations and are converted into ordinary differential equations via similarity transformations. These equations are then solved by the Finite Element Method. The effect of various important parameters on nondimensional velocity, temperature distribution, nanoparticle concentration, the density of motile micro-organisms is analyzed graphically in detail. It is observed from the obtained results that the flow velocity decreases with rising angle of inclination [Formula: see text] while temperature, nanoparticle’s concentration and density of motile micro-organisms increase. The local skin friction coefficient, Nusselt number, Sherwood number, motile micro-organism’s density number are calculated. It is noticed that increasing the Brownian motion and thermophoresis parameter leads to an increase in temperature of fluid which results in a reduction in Nusselt number. On the contrary, the Sherwood number rises with an increase in Brownian motion and thermophoresis parameter. Also, interesting features of the flow dynamics are elaborated and new future pathways for extension of the study identified in bio-magneto-nano polymers (BMNPs) for solar coatings.

The characteristics of buoyancy-driven convection of nanofluid stream containing motile gyrotactic micro-organisms over a continuous heated surface are explored. The benefits of including micro-organisms to the suspension incorporate micro-scale mixing and foreseen enhanced stability of nanofluid. For heat transfer and mass transfer processes, non-Fourier’s heat flux theory and non-Fick’s mass flux theory are employed. This theory is actively under investigation to resolve some drawbacks of the famous Fourier’s Law and Fick’s Law. The modified parameters in conventional laws are thermal and solutal relaxation times, respectively. The governing equations are remodeled using appropriate similarity transformations into a system of coupled ordinary differential equations. Finite Element Methodology is used to obtain the solution of nonlinear coupled differential equations. The governing equations are associated with dimensionless parameters like [Formula: see text]. The influence of these parameters is analyzed graphically on velocity, temperature profile, concentration profile and density of micro-organisms. The computational results obtained reveal that the temperature profile and concentration profile have an inverse relationship with thermal relaxation and solutal relaxation time, respectively. Furthermore, the velocity increases with increasing values of the Richardson number, while a reverse pattern is observed for bioconvection Rayleigh number and Buoyancy ratio parameter.

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