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ABSTRACTThe present model is devoted for the steady stagnation point flow of a Williamson micropolar nanofluid with magneto-hydrodynamics and thermal radiation effects passed over a horizontal porous stretching sheet. The fluid is considered to be gray, absorbing-emitting but non-scattering medium. The Cogley-Vincent-Gilles formulation is adopted to simulate the radiation component of heat transfer. By applying similarity analysis, the governing partial differential equations are transformed into a set of non-linear ordinary differential equations and they are solved by using the bvp4c package in MATLAB. Numerical computations are carried out for various values of the physical parameters. The effects of momentum, microrotation, temperature and nanoparticle volume fraction profiles together with the reduced skin friction coefficient, reduced Nusselt number and reduced Sherwood number of both active and passive controls on the wall mass flux are graphically presented. The present results are compared with previously obtained solutions and they are in good agreement. Results show that the skin friction is increasing functions of the Williamson parameter in both stretching and shrinking surfaces.

The present work deals with an inclined magnetohydrodynamic flow of a micropolar fluid occurring between two stretchable disks rotating co-axially at a constant distance apart by taking into account higher order chemical reaction effects. Using similarity variables the Navier–Stokes equations, which represent the momentum, microrotation, energy, and concentration, are transformed into ordinary differential equations. The transformed conservation equations are solved numerically by using the Nachtsheim–Swigert shooting iteration technique along with sixth-order Runge–Kutta integration scheme. The influence of governing parameters are shown graphically and discussed. It was observed that an increase in the aligned angle strengthens the applied magnetic field and decreases the momentum boundary layer profiles of the micropolar fluid flow. Heat transfer rate reduces for larger values of chemical reaction Crfor both n= 1 and n= 2.

AbstractAn investigation has been carried out to study the effect of hydrodynamic boundary layer flow over an unsteady porous stretching surface in the presence of non-uniform heat source/sink. Heat transfer characteristics are examined for variable wall temperature and variable heat flux of boundary conditions. The governing equations are transformed to ordinary differential equations by similarity transformation and solved numerically by Runge-Kutta fourth order method in association with quasilinear shooting technique. The effects of unsteadiness parameter, permeability parameter, magnetic parameter, Prandtl number and heat source or sink parameter are represented graphically and discussed.

•CuO nanoparticles were successfully doped onto SiO2nanoparticles.•SiO2Np`s synthesized from rice husk was characterized by XRD.•Doped CuO@SiO2Np`s were characterized by FTIR analysis.•The catalytic degradation of 4-nitrophenol and antimicrobial activity of CuO@SiO2NP`s were observed significantly.