Unsteady thermally radiative and chemically reactive viscoelastic fluid flow past a vertical porous plate with a heat source

An analytical study is performed to investigate the thermal radiation effect on the unsteady two-dimensional magnetohydrodynamic flow of a viscoelastic incompressible fluid (Walters $B\prime$ fluid model) along an infinite hot vertical sheet embedded in a porous medium. Further, the addition of a heat source in the energy equation as well as a chemical reaction in the concentration equation renders the present analysis realistic in the field of engineering and technology. The governing equations of mass, momentum, energy, and concentration are solved with successive perturbation techniques. The effects of pertinent parameters on fluid velocity, temperature, concentration, and bounding surface coefficients are shown graphically and in tabular form. The salient feature of the present study is to impose control on magnetic field strength vis-à-vis electromagnetic force by regulating voltage in the electric circuit. The important findings are: the elasticity property of the fluid is more sensitive to heated bounding surface consequently free convection current in enhancing the velocity near the plate than the inherent property viscosity. This outcome contributes to the design requirement to control the flow near the heated surface, higher values of frequency parameters contribute to the attainment of a free stream state in temperature distribution. Besides the aforesaid outcome, the present model is conducive to thinning of boundary layer as the elasticity, magnetic as well as free convection parameters enhance the force coefficients at the bounding surface.     

Heat and mass transfer of water-based copper and alumina hybrid nanofluid over a stretching sheet

Hybrid nanofluids (HNFs) are vital in engineering and industrial applications due to significant effective thermal conductivity as compared with regular fluid and nanofluid (NF). The HNF is a process of the conglomeration of two or more nanoparticles of different thermophysical properties to affect the thermal transport characteristics of base fluid, particularly in gearing up heat switch charge. Further, the impact of HNF combined with stretching and squeezing of bounding surface has direct application in thinning/thickening of polymeric sheets in the chemical industry. The current study analyzes the flow of HNF over a stretching sheet under the influence of chemical reaction as well as suction/injection. We have considered water $\left({\mathrm{H}}_2\mathrm{O}\right)$ as the base fluid and copper $\left(\mathrm{Cu}\right)$, and aluminum oxide $\left({\mathrm{Al}}_2{\mathrm{O}}_3\right)$ as nanoparticles. The consequences of the magnetic field, viscous dissipation, and Joule heating are also to be investigated. The resulting partial differential equations are transformed into nonlinear ordinary differential equations using suitable similarity transformations. The numerical solutions to governing equations are obtained with the help of MATLAB software using the bvp4c solver. The important finding is: the rate of heat transfer of HNF is higher than that of NF as well as base fluid. Moreover, contributions of higher Eckert number and radiation parameter are to increase the temperature in the flow domain, whereas the Prandtl number reduces it. It is further noticed that heavier species as well as viscous dissipation decline the level of concentration across the flow field.