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In this article, the model of a non-Newtonian fluid (Thixotropic) flow past a vertical surface in the presence of exponential space and temperature dependent heat source in a thermally stratified medium is studied. It is assumed that free convection is induced by buoyancy and exponentially decaying internal heat source across the space. The dynamic viscosity is taken to be constant and thermal conductivity of this particular fluid model is assumed to vary linearly with temperature. Thermal stratification has been properly incorporated into the governing equation so that its effect can be revealed and properly reported. The governing partial differential equations describing the model are transformed and parameterized to a system of non-linear ordinary differential equation using similarity transformations. Approximate analytic solutions were obtained by adopting Optimal Homotopy Analysis Method (OHAM). The results show that for both cases of non-Newtonian parameters (Thixotropic) (1 2 0 K K = = & 1 2 1.0 K K = =), increasing stratification parameters, relate to decreasing in the heat energy entering into the fluid region and thus reducing the temperature of the Thixotropic fluid as it flows.

In this paper, the fluid examined was electrically conducting. The presence of a uniform transverse magnetic field at the plate was also taken into cognizance. The flow was governed by a modeled coupled nonlinear system of partial differential equations (PDEs) in dimensional form which was transformed into non-dimensional form using some non-dimensional variables. Explicit finite difference method (EFDM) was employed to approximate the fluid velocity, temperature and concentration. The effects of embedded thermo physical parameters of engineering interests on the flow quantities viz. velocity, temperature, concentration field presented through graphs were also examined through a series of numerical experiments and discussed. During the course of the numerical computations, it was found that heat generation has a tendency to enhance the fluid velocity as an opposite result is seen with chemical reaction parameter. A comparison was conducted of present results with the previous literature to show the accuracy of the results.

A numerical computational treatment of transient electrically conducting fluid with an Arrhenius chemical reaction in the presence of Navier slip and Newtonian heating is obtained by using implicit finite difference scheme. A transverse magnetic field is applied to the flow direction due to the exothermic nature of the fluid. Numerical computation shows that, higher values of Frank-Kamenetskii parameter (λ) and Biot number (Br) significantly influence the transport phenomenon. Irrespective of smaller or larger time, Magnetic parameter (M) reduces velocity of the fluid as well as wall shear stress.

This article presents the analytic solution to a steady, incompressible, free convective flow of an electrically conducting second grade fluid past a vertical surface with variable properties namely: variable viscosity; variable thermal conductivity and variable concentration diffusivity in the presence of thermophoresis, chemical reaction and convective boundary condition. The impact of different orders of chemical reaction on thermophoresis and the transport process of flow, heat and mass transfer in the boundary layer for assisting and opposing flow cases are properly examined and discussed. The governing equations associated with the fluid model are transformed and parameterized to a system of coupled nonlinear ordinary differential equations using similarity transformations. The resulting coupled ordinary differential equations (ODEs) were solved by adopting the Optimal Homotopy Analysis Method (OHAM).  The results indicate that velocity and temperature distributions are decreasing functions of second grade parameter for both cases of assisting and opposing flows.  Also, concentration distribution is a decreasing function of thermophoretic parameter for low and high orders of chemical reaction.

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The study considers the case of the unequal diffusion coefficients of reactant $A$ (bulk fluid) and reactant $B$ (catalyst at the wall) with the dispersion of both nanoparticles and gyrotactic microorganisms of Erying-Powell fluid flow over a surface with non-uniform thickness in the presence of variable fluid properties and stratification. The numerical solution of the transformed governing equations is obtained by using the Runge-Kutta method and shooting techniques. The outcome of this study is that the increasing values of temperature-dependent thermal conductivity parameter lead to the augmentation of the kinetic energy which thereafter causes a significant enhancement of the fluid temperature.