The effects of radiation optical properties on the unsteady 2D boundary layer MHD flow and heat transfer over a stretching plate

• Published in: International journal of heat and mass transfer Vol. 105; pp. 109 - 123
• Main Authors: Tian, Xi-Yan, Li, Ben-Wen, Zhang, Jing-Kui
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2017; Elsevier BV
• Subjects: Boundary conditions; Boundary layer; Chebyshev approximation; Chebyshev collocation spectral method (CCSM); Collocation methods; Convective heat transfer; Fluid flow; Force distribution; Heat flux; Heat transfer; Joule heating; Laminar boundary layer; Laminar flow; Laminar heat transfer; Lorentz force; Magnetic fields; Magnetic properties; Magnetohydrodynamic flow; Magnetohydrodynamics; Magnetohydrodynamics (MHD); Optical properties; Optical thickness; Physical properties; Radiation effects; Resistance heating; Spectral methods; Stretching; Temperature distribution; Thermal radiation; Two dimensional flow; Viscous dissipation; Magnetohydrodynamics (MHD); Viscous dissipation; Optical properties; Chebyshev collocation spectral method (CCSM); Joule heating; Boundary layer
• DOI: 10.1016/j.ijheatmasstransfer.2016.09.060
• ISSN: 0017-9310

•Effects of the radiative optical properties on MHD boundary layer.•Radiative heat flux is obtained by solving the radiation transfer equation.•Effect of the wall emissivity of the plate on the temperature distribution.•The viscous dissipation and the Joule heating are also considered.•The MHD participating medium can be from optical thin to thick ones. In this work, the effects of radiation optical properties and Lorentz force on the 2D unsteady laminar boundary magnetohydrodynamic (MHD) fluid flow and heat transfer along a semi-infinite stretching plate are numerically investigated, the Joule heating effect and viscous dissipation are considered. The heat flux caused by the thermal radiation is obtained by solving the radiation transfer equation (RTE) instead of the Rosseland approximation. All the governing equations, including continuous equation, momentum equation, energy equation, and RTE subject to the boundary radiative emission, are transformed into dimensionless forms. The dimensionless governing equations together with the corresponding boundary conditions are solved numerically via Chebyshev collocation spectral method (CCSM). The effects of various physical parameters, say, Ha, Pr, Ec and Pl, especially the optical properties such as the optical thickness, the scattering albedo, and the wall emissivity of the plate, on the flow and heat transfer are depicted graphically and analyzed in detail. It is found that, due to the thermal radiation, the overall average temperature within the boundary layer becomes much higher and the boundary layer becomes thicker. The magnetic force can suppress the fluid flow significantly and stop the convective heat transfer effectively. Viscous dissipation and Joule heating greatly enhance the temperature distribution with the help of the magnetic field.