Thermal radiation effect on unsteady MHD free convection flow past a vertical plate with temperature‐dependent viscosity

Abstract

This article investigates the influence of radiation and temperature-dependent viscosity on the problem of unsteady MHD flow and heat transfer of an electrically conducting fluid past an infinite vertical porous plate taking into account the effect of viscous dissipation. The governing equations are converted into a system of nonlinear ordinary differential equations via a local similarity parameter which is taken as a function of time. The resulting system of coupled nonlinear ordinary differential equations is solved numerically using the fourth order Runge-Kutta integration scheme with the shooting method. The numerical results for the velocity and the temperature are displayed graphically showing the effects of various parameters. The results show that increasing the Eckert number and decreasing the viscosity of air leads to a rise in the velocity, while increasing in the magnetic or the radiation parameters is associated with a decrease in the velocity. Also, an increase in the Eckert number leads to an increase in the temperature, whereas an increase in radiation parameter leads to a decrease in the temperature.On aétudié dans cet article l'influence de la radiation et de la viscosité thermodépendante sur le problème d'écoulement MHD instable et le transfert de chaleur dans le cas d'un fluideélectriquement conducteurà travers un plateau poreux vertical infini en tenant compte de l'effet de la dissipation visqueuse. Leséquations gouvernantes ontété converties en un système d'équations différentielles ordinaires non linéaires grâceà un paramètre de similarité local considéré comme variable dans le temps. Le système d'équations différentielles ordinaires non linéaires couplées ainsi obtenu aété résolu numériquementà l'aide d'un schéma d'intégration de Runge-Kutta de quatrième ordre par la méthode de tir. Les résultats numériques de vitesse et de température sont illustrés par des graphiques montrant les effets des divers paramètres. Ces résultats montrent que l'augmentation du nombre d'Eckert et la diminution de la viscosité de l'air conduisentà une augmentation de la vitesse, tandis que l'augmentation des paramètres magnétiques ou de radiation est associéeà une diminution de la vitesse. De même, une augmentation du nombre d'Eckert conduit a une augmentation de la température, tandis qu'une augmentation du paramètre de radiation mèneà une diminution de la température.

A Study of Chemically Reactive Species and Thermal Radiation Effects on an Unsteady MHD Free Convection Flow Through a Porous Medium Past a Flat Plate with Ramped Wall Temperature

“…The expression for the skin friction for the ramped temperature plate is given by 19) and for the isothermal plate it is given by…”

“…Suneetha et al [18] studied the effects of thermal radiation on an MHD free convection flow past an impulsively started vertical plate with variable surface temperature and concentration. Mahmoud [19] studied the effect of thermal radiation on an unsteady MHD free convection flow past a vertical plate with temperature dependent viscosity. Seth et al [20] studied the effects of thermal radiation and rotation on an unsteady hydromagnetic free convection flow past an impulsively moving vertical plate with ramped temperature in a porous medium.…”

MHD convective heat transfer with temperature-dependent viscosity and thermal conductivity: a numerical investigation

“…First, The viscosity is an inverse linear function of temperature in many works [1,13,19,20,24,29,30]. Second, an exponentially varying viscosity was considered in much literature [3,16,18]. Based on the analysis of Capone and Gentile [3] and Jenkins [12], for most fluids the exponentially dependent viscosity seems to be the most appropriate according to the experimental results, moreover, it has been underlined that the linear dependence is realistic for small values of the viscosity ratio of between at the top and at the bottom of the layer.…”

Numerical Study for the Flow and Heat Transfer in a Thin Liquid Film Over an Unsteady Stretching Sheet with Variable Fluid Properties in the Presence of Thermal Radiation

“…Therefore it is necessary to take the variation of viscosity and thermal conductivity into consideration. The viscosity is assumed to vary exponentially with the temperature [18,19] and the thermal conductivity is assumed to vary linearly with the temperature [20][21][22]. Dandapat et al [23] discussed the effects of variable viscosity, variable thermal conductivity and thermocapillarity on the flow and heat transfer within a thin liquid film over an unsteady stretching sheet.…”