An Unsteady Nanofluid Flow Past Parallel Porous Plates: A Numerical Study

Abstract

Background: This study investigates an unsteady, two-dimensional, incompressible viscous boundary layer flow of an electrically conducting nanofluid past parallel plates. The plates are permeable to allow both suction and injection to take place. It is assumed that viscosity, thermal conductivity and mass diffusivity of the nanofluid vary with temperature. The novelty of this study is in consideration of the combined effects of chemical reaction, permeability, externally applied magnetic field, and momentum diffusivity on the flow varibles. The magnetic field force is significant because it provides information regarding the boundary layer characteristics. Methods: The highly nonlinear partial differential equations are solved numerically using the newly developed bivariate spectral quasilinearization method (BSQLM) along with varying thermal and concentration boundary conditions. The BSQLM method is an innovative technique that is more reliable and robust as it demands fewer grid points and has a global approach to solving PDEs. Results: An analysis and comparison of results with existing literature are reported. Excellent agreement has been found between our results and those previously published. Among the findings, we show, inter alia, a significant increase in the profiles for fluid velocity, temperature and concentration with an increase in the chemical reaction, applied magnetic field, and thermal radiation. The BSQLM converges fast and is computationally efficient when applied to boundary layer problems that are defined on a large computational domain. Conclusions: A numerical study on nanofluid flow between parallel porous plates has been carried out, and here are the key findings: 1. Heat flux is directly related to thermal radiation, the applied magnetic field, permeability, and the chemical reaction involved. 2. Mass flux increases with increased chemical reaction, permeability, and the magnetic parameters. 3. The nanofluid concentration is directly related to the Prandtl and magnetic numbers and inversely related to the Reynolds number and chemical reaction. 4. The skin-friction coefficient reduces with higher values of magnetic field and permeability parameters and increases with an increment in thermal radiation and chemical reaction. 5. The BSQLM has a high convergence rate with high accuracy.