G. S. Seth

Analysis of hydromagnetic natural convection radiative flow of a viscoelastic nanofluid over a stretching sheet with Soret and Dufour effects

Purpose The purpose of this paper is to assess steady, two-dimensional natural convection flow of a viscoelastic, incompressible, electrically conducting and optically thick heat-radiating nanofluid over a linearly stretching sheet in the presence of uniform transverse magnetic field taking Dufour and Soret effects into account. Design/methodology/approach The governing boundary layer equations are transformed into a set of highly non-linear ordinary differential equations using suitable similarity transforms. Finite element method is used to solve this boundary value problem. Effects of pertinent flow parameters on the velocity, temperature, solutal concentration and nanoparticle concentration are described graphically. Also, effects of pertinent flow parameters on the shear stress, rate of heat transfer, rate of solutal concentration and rate of nanoparticle concentration at the sheet are discussed with the help of numerical values presented in graphical form. All numerical results for mono-diffusive nanofluid are compared with those of double-diffusive nanofluid. Findings Numerical results obtained in this paper are compared with earlier published results and are found to be in excellent agreement. Viscoelasticity, magnetic field and nanoparticle buoyancy parameter tend to enhance the wall velocity gradient, whereas thermal buoyancy force has a reverse effect on it. Radiation, Brownian and thermophoretic diffusions tend to reduce wall temperature gradient, whereas viscoelasticity has a reverse effect on it. Nanofluid Lewis number tends to enhance wall nanoparticle concentration gradient. Originality/value Study of this problem may find applications in engineering and biomedical sciences,e.g. in cooling and process industries and in cancer therapy.

Hydromagnetic flow of heat absorbing and radiating fluid over exponentially stretching sheet with partial slip and viscous and Joule dissipation

Purpose – The purpose of this paper is to investigate hydromagnetic two dimensional boundary layer flow with heat transfer of a viscous, incompressible, electrically conducting, heat absorbing and optically thick heat radiating fluid over a permeable exponentially stretching sheet considering the effects of viscous and Joule dissipations in the presence of velocity and thermal slip. Design/methodology/approach – Using similarity transform, governing differential equations representing mathematical model of the problem are solved with the help of fourth-order Runge-Kutta method along with shooting technique. Numerical solutions of fluid velocity and fluid temperature are depicted graphically for various values of pertinent flow parameters whereas numerical values of wall velocity gradient and wall temperature gradient are displayed graphically for various values of pertinent flow parameters. Findings – Numerical results obtained in this paper are compared with earlier published results and are found to be ...

Effects of Hall current on unsteady hydromagnetic free convection flow past an impulsively moving vertical plate with Newtonian heating

Abstract An investigation of unsteady hydromagnetic free convection flow of a viscous, incompressible and electrically conducting fluid past an impulsively moving vertical plate with Newtonian surface heating embedded in a porous medium taking into account the effects of Hall current is carried out. The governing partial differential equations are first subjected to the Laplace transformation and then inverted numerically using INVLAP routine of Matlab. The governing partial differential equations are also solved numerically by the Crank-Nicolson implicit finite difference scheme and a comparison has been provided between the two solutions. The numerical solutions for velocity and temperature are plotted graphically whereas the numerical results of skin friction and the Nusselt number are presented in tabular form for various parameters of interest. The present solution in special case is compared with a previously obtained solution and is found to be in excellent agreement.

Analysis of Radiative Magneto-Nanofluid over an Accelerated Plate in a Rotating Medium with Hall Effects

Present research work has been undertaken to analyze the effects of Hall current on natural convective flow of radiative, incompressible, viscous and electrically conducting magneto-nanofluid over a uniformly accelerated moving vertical ramped temperature plate in a rotating medium. Three types of water based nanofluids containing the nanoparticles of alumina, copper and titanium oxide have been accounted. The mathematical model of the problem has been presented using the nanoparticle volume fraction model. The Laplace transform technique has been employed to solve the mathematical model. The closed-form expressions of nanofluid velocity, temperature, shear stress and rate of heat transfer at the plate have been obtained for both the conditions of ramped temperature and isothermal plates. The effects of various physical parameters on the nanofluid velocity due to primary and secondary flows and temperature have been exemplified using various graphs whereas, the numerical values of shear stress and rate of heat transfer at the plate have been reported in tabular form for different values of physical parameters of interest. Moreover, the numerical results have been compared for the natural convective flow near ramped temperature plate with the corresponding flow near isothermal plate. It has been noted that both the nanofluid velocity and temperature are higher in magnitude in the case of isothermal plate than that of ramped temperature plate. The results of present research work have been validated with the earlier published work.

Radiation Effect on MHD Convective Flow of Nanofluids over an Exponentially Accelerated Moving Ramped Temperature Plate

The effect of thermal radiation on magnetohydrodynamic free convective flow of incompressible and viscous nanofluids, which is electrically conducting, over an exponentially accelerated moving ramped temperature plate is studied. The water-based nanofluids which contain the nanoparticles of copper, alumina, and titanium oxide are taken into consideration. The mathematical model of the problem is formulated by applying the nanoparticle volume fraction model. The governing equations for the flow, subjected to the associated conditions, have been solved analytically by Laplace transform method. Expressions of nanofluid velocity, temperature, shear stress, and Nusselt number have been obtained in compact form. Effects of controlling physical parameters on nanofluid velocity and temperature have been displayed using various graphs, whereas, for the engineering perspective, numerical values of shear stress are presented in table.

Unsteady MHD Natural Convective Flow of a Rotating Fluid over an Infinite Vertical Plate due to Oscillatory Movement of the Free-Stream with Hall and Ion-Slip Currents

In the present research study a mathematical analysis has been presented for unsteady MHD natural convective flow of a rotating fluid over an infinite vertical plate immersed in a fluid saturated porous medium with oscillating free-stream. The effects of Hall and ion-slip currents also considered on the fluid flow. The unsteady MHD flow over the vertical plate is induced due to thermal and concentration buoyancy forces and oscillatory movement of the free-stream. The partial differential equations governing the motion for the fluid flow are solved analytically. The effects of various pertinent flow parameters on the fluid velocity, fluid temperature and species concentration are presented in graphical form whereas that on skin friction and rate of heat and mass transfer at the plate are presented in tabular form. An interesting observation recorded from the present analysis that there appears reversal flow in the secondary flow direction due to presence of thermal and/or concentration buoyancy forces. However, in the absence of both reversals flow does not exist in the secondary flow direction. It is also noted that the thickness of momentum boundary layer decreases with rise in frequency of oscillations of the free-stream.

MHD Stagnation Point Flow over Exponentially Stretching Sheet with Exponentially Moving Free-Stream, Viscous Dissipation, Thermal Radiation and Non-Uniform Heat Source/Sink

An investigation is carried out for the steady, two dimensional stagnation point flow of a viscous, incompressible, electrically conducting, optically thick heat radiating fluid taking viscous dissipation into account over an exponentially stretching non-isothermal sheet with exponentially moving free-stream in the presence of uniform transverse magnetic field and non-uniform heat source/sink. The governing boundary layer equations are transformed into highly nonlinear ordinary differential equations using suitable similarity transform. Resulting boundary value problem is solved numerically with the help of 4th-order Runge-Kutta Gill method along with shooting technique. Effects of various pertinent flow parameters on the velocity, temperature field, skin friction and Nusselt number are described through figures and tables. Also, the present numerical results are compared with the earlier published results for some reduced case and a good agreement has been found among those results.

MHD NATURAL CONVECTION FLOW WITH RADIATIVE HEAT TRANSFER PAST AN IMPULSIVELY MOVING VERTICAL PLATE WITH RAMPED TEMPERATURE IN THE PRESENCE OF HALL CURRENT AND THERMAL DIFFUSION

Abstract An investigation on an unsteady MHD natural convection flow with radiative heat transfer of a viscous, incompressible, electrically conducting and optically thick fluid past an impulsively moving vertical plate with ramped temperature in a porous medium in the presence of a Hall current and thermal diffusion is carried out. An exact solution of momentum and energy equations, under Boussinesq and Rosseland approximations, is obtained in a closed form by the Laplace transform technique for both ramped temperature and isothermal plates. Expressions for the skin friction and Nusselt number for both ramped temperature and isothermal plates are also derived. The numerical values of fluid velocity and fluid temperature are displayed graphically versus the boundary layer coordinate y for various values of pertinent flow parameters for both ramped temperature and isothermal plates. The numerical values of the skin friction due to primary and secondary flows are presented in tabular form for various values of pertinent flow parameters.