Hydromagnetic-oscillatory flow of a nanofluid with Hall effect and thermal radiation past vertical plate in a rotating porous medium

2018 ◽  
Vol 14 (2) ◽  
pp. 360-386 ◽  
Author(s):  
Sreedevi Gandluru ◽  
Prasada Rao D.R.V. ◽  
O.D. Makinde
Keyword(s):  
Porous Medium ◽  
Thermal Radiation ◽  
Hall Effect ◽  
Oscillatory Flow ◽  
Vertical Plate ◽  
Hall Current ◽  
Local Skin ◽  
Content Type ◽  
Special Cases ◽  
The Impact

Purpose The purpose of this paper is to investigate the impact of thermal radiation interaction with Hall current, buoyancy force, and oscillatory surface temperature on hydromagnetic-mixed convective heat exchange stream of an electrically conducting nanofluid past a moving permeable plate in a porous medium within a rotating system. Design/methodology/approach Analytical closed-form solutions are obtained for both the momentum and the energy equations using the perturbation method. Findings The effects of various important parameters on velocity and temperature fields within the boundary layer are discussed for three different water-based nanofluids containing copper (Cu), aluminum oxide (Al2O3), and titanium dioxide (TiO2) as nanoparticles. Local skin friction and Nusselt number are illustrated graphically and discussed quantitatively. The results show that Hall current significantly affects the flow system. Results for some special cases of the present analysis are in good agreement with the existing literature. Originality/value The problem is relatively original to study the hydromagnetic-oscillatory flow of a nanofluid with Hall effect and thermal radiation past a vertical plate in a rotating porous medium.

Finite difference approach in porous media transport modeling for magnetohydrodynamic unsteady flow over a vertical plate

2014 ◽  
Vol 24 (5) ◽  
pp. 1204-1223 ◽  
Author(s):  
Sahin Ahmed ◽  
Abdul Batin ◽  
Ali J. Chamkha
Keyword(s):  
Nusselt Number ◽  
Finite Difference ◽  
Thermal Radiation ◽  
Drag Force ◽  
Local Nusselt Number ◽  
Vertical Plate ◽  
Two Dimensional ◽  
Local Skin ◽  
Content Type ◽  
Electrically Conducting

Purpose – The purpose of this paper is to examine the effects of Darcian drag force and radiation-conduction on unsteady two-dimensional magnetohydrodynamic flow of viscous, electrically conducting and Newtonian fluid over a vertical plate adjacent to a Darcian regime in presence of thermal radiation and transversal magnetic field. A well-tested, numerically stable Crank-Nicolson finite-difference procedure is employed for the conservation equations. Excellent agreement is obtained for numerical solutions with previously published work. Design/methodology/approach – In this investigation, an efficient, accurate, extensively validated and unconditionally stable finite-difference scheme based on the Crank-Nicolson model is developed to solve the governing coupled, non-linear partial differential equations. The accuracy and effectiveness of the method are demonstrated. Findings – Different numerical results are obtained and presented graphically to explain the effect of various physical parameters on the velocity and temperature profiles, local, as well as average, skin friction and Nusselt number. It is found that, with a rise in Darcian drag force, flow velocity and temperature are reduced, but increased for all times. Both average and local skin frictions are reduced considerably with an increase in Darcian drag force, but reversed behavior is observed for the local Nusselt number. Increasing the thermal radiation effects accelerated the flow velocity as well as the fluid temperature and wall local skin friction in a saturated porous medium, but effectively reduced the local Nusselt number and average Nusselt number at the wall. Comparison with previously published works in the limits shows excellent agreement. Research limitations/implications – The analysis is valid for unsteady, two-dimensional laminar flow of an optically thick no-gray gas, electrically conducting, and Newtonian fluid past an isothermal vertical surface adjacent to the Darcian regime with variable surface temperature. An extension to three-dimensional flow case is left for future work. Practical implications – Practical interest of such study includes applications in electromagnetic lubrication, boundary cooling, bio-physical systems and in many branches of engineering and science. It is well known that the effect of thermal radiation is important in space technology and high temperature processes. Thermal radiation also plays an important role in controlling heat transfer process in polymer processing industry.

scholarly journals Hall current and joule heating effects on free convection flow of a nanofluid over a vertical cone in presence of thermal radiation

2017 ◽  
Vol 21 (6 Part A) ◽  
pp. 2609-2620 ◽  
Author(s):  
Wael Abbas ◽  
Emad Sayed
Keyword(s):  
Thermal Radiation ◽  
Joule Heating ◽  
Volume Fraction ◽  
Hall Current ◽  
Flow Behavior ◽  
Nanoparticle Volume Fraction ◽  
Vertical Cone ◽  
Local Skin ◽  
Special Cases ◽  
Non Linear

The effects of Hall current and Joule heating on flow and heat transfer of a nanofluid along a vertical cone in the presence of thermal radiation is considered. The flow is subjected to a uniform strong transverse magnetic field normal to the cone surface. Similarity transformations are used to convert the non-linear boundary- layer equations for momentum and energy equations to a system of non-linear ordinary differential equations which are then solved numerically with appropriate boundary conditions. The solutions are presented in terms of local skin friction, local Nusselt number, velocity, and temperature profiles for values of magnetic parameter, Hall parameter, Eckert number, radiation parameter, and nanoparticle volume fraction. Comparison of the numerical results made with previously published results under the special cases, the results are found to be in an excellent agreement. It is also found that, nanoparticle volume fraction parameter and types of nanofluid play an important role to significantly determine the flow behavior.

The impact of “distance” on multinational enterprise subsidiary capabilities

2016 ◽  
Vol 24 (2) ◽  
pp. 168-190 ◽  
Author(s):  
Alain Verbeke ◽  
Wenlong Yuan
Keyword(s):  
Value Chain ◽  
Design Methodology ◽  
Cultural Distance ◽  
Geographic Distance ◽  
Multinational Enterprise ◽  
Foreign Subsidiaries ◽  
Content Type ◽  
Special Cases ◽  
Mne Subsidiary ◽  
The Impact

Purpose The aim of this paper is to investigate how multinational enterprise (MNE) subsidiary capabilities are influenced by the firm-specific advantages (FSAs) of the parent company, as well as by cultural and geographic distance between the home and host country. Design/methodology/approach This paper assesses how the effects of the parent FSAs, cultural distance and geographic distance on subsidiary capabilities vary for different value-chain activities, with an empirical application to 60 foreign subsidiaries operating in Canada. Findings This paper uncovers distinct, three-way interaction effects among parent-level FSAs, cultural distance and geographic distance for upstream versus downstream activities in the value chain. Originality/value We find that in special cases, high levels of distance can be positive for MNEs, in terms of driving the creation of stronger subsidiary capabilities.

scholarly journals The Effects of Thermal Radiation, Hall Currents, Soret, and Dufour on MHD Flow by Mixed Convection over a Vertical Surface in Porous Media

2010 ◽  
Vol 2010 ◽  
pp. 1-20 ◽  
Author(s):  
Stanford Shateyi ◽  
Sandile Sydney Motsa ◽  
Precious Sibanda
Keyword(s):  
Mixed Convection ◽  
Thermal Radiation ◽  
Hall Current ◽  
Mhd Flow ◽  
Vertical Surface ◽  
Similarity Solutions ◽  
Special Cases ◽  
Permeability Parameter ◽  
Magnetic Strength ◽  
Good Agreement

The study sought to investigate the influence of a magnetic field on heat and mass transfer by mixed convection from vertical surfaces in the presence of Hall, radiation, Soret (thermal-diffusion), and Dufour (diffusion-thermo) effects. The similarity solutions were obtained using suitable transformations. The similarity ordinary differential equations were then solved by MATLAB routinebvp4c. The numerical results for some special cases were compared with the exact solution and those obtained by Elgazery (2009) and were found to be in good agreement. A parametric study illustrating the influence of the magnetic strength, Hall current, Dufour, and Soret, Eckert number, thermal radiation, and permeability parameter on the velocity, temperature, and concentration was investigated.

scholarly journals Hall Current and Thermal Radiation Effects on Heat and Mass Transfer of Unsteady MHD Flow of a Viscoelastic Micropolar Fluid through a Porous Medium

2020 ◽  
Vol 68 (1) ◽  
pp. 1-10
Author(s):  
Lavanya
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Thermal Radiation ◽  
Micropolar Fluid ◽  
Radiation Effects ◽  
Hall Current ◽  
Perturbation Technique ◽  
Mhd Flow ◽  
Skin Friction Coefficient ◽  
Governing Equations

The present paper is concerned to analyze the effect of hall current on heat and thermal radiation and mass transfer of unsteady MHD flow of a viscoelastic micropolar fluid through a porous medium with chemical reaction. The governing partial differential equations are transformed to dimensionless equations using dimensionless variables. The dimensionless governing equations are then solved analytically using perturbation technique. The effects of various governing parameters on the velocity, temperature, concentration, skin-friction coefficient, Nusselt number and Sherwood number are shown in figures and tables and analyzed in detail.

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