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In this paper, two-dimensional non-Newtonian couple stress fluid flow over the upper horizontal surface of a paraboloid (uhsp) (shaped like a submarine or any aerodynamical automobile) is investigated. At the freestream, a stretching of the fluid layer is assumed along with catalytic surface reaction which tends to induce the flow in the fluid-saturated domain. The problem is modeled by engaging laws of conservation for mass, momentum, heat and concentration. Velocity components are converted to stream functions and similarity transformations to reduce the dependent and independent variables in the partial differential equation describing the flow. Stream functions ideally satisfy continuity equation and transformation to reduce the PDEs to the system of coupled nonlinear ODEs. The numerical solution of these equations is obtained using the shooting-RKF method. The graphical results show that both the lateral and horizontal velocities decrease by increasing the couple stress material parameter and cause the temperature to rise. The thermal boundary layer decreases subject to the thickness parameter and has appositive effects on concentration boundary layer. Finally, numerical results have also been tabulated.

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These days, heat transfer plays a significant role in the fields of engineering and energy, particularly in the biological sciences. Ordinary fluid is inadequate to transfer heat in an efficient manner, therefore, several models were considered for the betterment of heat transfer. One of the most prominent models is a single-phase nanofluid model. The present study is devoted to solving the problem of micropolar fluid with a single-phase model in a channel numerically. The governing partial differential equations (PDEs) are converted into nonlinear ordinary differential equations (ODEs) by introducing similarity transformation and then solved numerically by the finite difference method. Response surface methodology (RSM) together with sensitivity analysis are implemented for the optimization analysis. The study reveals that sensitivity of the skin friction coefficient (Cfx) to the Reynolds number (R) and magnetic parameter (M) is positive (directly proportional) and negative (inversely proportional) for the micropolar parameter.

The author presents the influence of Arrhenius activation energy and binary chemical reaction on an unsteady magnetohydrodynamics Williamson nanofluid with motile gyrotactic micro‐organisms. The governing equations are converted to coupled ordinary differential equations with similarity transformations and the fifth‐order Runge‐Kutta Fehlberg method and the shooting algorithm is applied to solve these equations using the appropriate boundary conditions. A detailed investigation considering the effects of different physical parameters on the profiles like velocity, temperature, concentration, and density of motile gyrotactic micro‐organisms was done and plotted graphically. It is found that the thermal boundary layer enhances for the chemical reaction rate and the solutal boundary layer increases for activation energy. Furthermore, the nondimensional Williamson parameter reduces for the velocity profile. The author studied the wall temperature gradient of different fluids and found that temperature gradient decreased for the present study. Comparisons of the present result with published work were done to verify the present code.