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Ali J Chamkha - One of the best experts on this subject based on the ideXlab platform.

  • combined effect of heat generation or absorption and first order chemical reaction on micropolar fluid flows over a uniformly stretched Permeable Surface
    International Journal of Thermal Sciences, 2009
    Co-Authors: Rebhi A Damseh, Ali J Chamkha, M Q Alodat, B Shannak
    Abstract:

    Abstract This work is focused on the study of combined heat and mass transfer by natural convection of a micropolar, viscous and heat generating or absorbing fluid flow near a continuously moving vertical Permeable infinitely long Surface in the presence of a first-order chemical reaction. The governing equations for this investigation are formulated and solved numerically using the fourth-order Runge–Kutta method. Comparisons with previously published work on special cases of the problem are performed and found to be in excellent agreement. A parametric study illustrating the influence of the micro-gyration parameter, vortex viscosity parameter, chemical reaction parameter, Schmidt number, heat generation or absorption parameter on the fluid velocity as well as the skin-friction coefficient and the Nusselt and Sherwood numbers is conducted. The results of this parametric study are shown graphically and the physical aspects of the problem are highlighted and discussed.

  • MHD Flow of a Micropolar Fluid past a Stretched Permeable Surface with Heat Generation or Absorption
    Nonlinear Analysis: Modelling and Control, 2009
    Co-Authors: M.-e. M. Khedr, Ali J Chamkha, M. Bayomi
    Abstract:

    This work considers steady, laminar, MHD flow of a micropolar fluid past a stretched semi-infinite, vertical and Permeable Surface in the presence of temperature- dependent heat generation or absorption, magnetic field and thermal radiation effects. A set of similarity parameters is employed to convert the governing partial differential equations into ordinary differential equations. The obtai ned self-similar equations are solved numerically by an efficient implicit, iterative, fini te-difference method. The obtained results are checked against previously published work for special cases of the problem in order to access the accuarcy of the numerical method and found to be in excellent agreement. A parametric study illustrating the i nfluence of the various physical parameters on the skin friction coefficient, microrotaion c oefficient or wall couple stress as well as the wall heat transfer coefficient or Nusselt numbe r is conducted. The obtained results are presented graphically and in tabular form and the physical aspects of the problem are discussed.

  • mhd mixed convection radiation interaction along a Permeable Surface immersed in a porous medium in the presence of soret and dufour s effects
    Heat and Mass Transfer, 2008
    Co-Authors: Ali J Chamkha, Abdullatif Bennakhi
    Abstract:

    This work is focused on the numerical modeling of steady, laminar, heat and mass transfer by MHD mixed convection from a semi-infinite, isothermal, vertical and Permeable Surface immersed in a uniform porous medium in the presence of thermal radiation and Dufour and Soret effects. A mixed convection parameter for the entire range of free-forced-mixed convection is employed and the governing equations are transformed into non-similar equations. These equations are solved numerically by an efficient, implicit, iterative, finite-difference scheme. The obtained results are checked against previously published work on special cases of the problem and are found to be in excellent agreement. A parametric study illustrating the influence of the thermal radiation coefficient, magnetic field, porous medium inertia parameter, concentration to thermal buoyancy ratio, and the Dufour and Soret numbers on the fluid velocity, temperature and concentration as well as the local Nusselt and the Sherwood numbers is conducted. The obtained results are shown graphically and the physical aspects of the problem are discussed.

  • Double-diffusive convection for a non-Newtonian fluid flow past a Permeable Surface embedded in a porous medium with uniform heat and mass fluxes
    2008
    Co-Authors: Ali J Chamkha
    Abstract:

    The problem of steady, laminar, double-diffusive mixed convective flow of a non-Newtonian power-law fluid past a vertical semi-infinite Permeable Surface embedded in a porous medium with uniform heat and mass fluxes. A mixed convection parameter for the entire range of free-forced-mixed convection is employed and a set of nonsimilar equations are obtained. These equations are solved numerically by an efficient implicit, iterative, finite-difference method. The obtained results are checked against previously published work for special cases of the problem and are found to be in good agreement. A parametric study illustrating the influence of the concentration to thermal buoyancy ratio, power-law fluid viscosity index, mixed convection parameter, suction or injection parameter and the Lewis number on the local Nusselt and the Sherwood numbers is conducted. The obtained results are shown graphically and the physical aspects of the problem are discussed.

  • MHD mixed convection–radiation interaction along a Permeable Surface immersed in a porous medium in the presence of Soret and Dufour’s Effects
    Heat and Mass Transfer, 2007
    Co-Authors: Ali J Chamkha, Abdullatif Ben-nakhi
    Abstract:

    This work is focused on the numerical modeling of steady, laminar, heat and mass transfer by MHD mixed convection from a semi-infinite, isothermal, vertical and Permeable Surface immersed in a uniform porous medium in the presence of thermal radiation and Dufour and Soret effects. A mixed convection parameter for the entire range of free-forced-mixed convection is employed and the governing equations are transformed into non-similar equations. These equations are solved numerically by an efficient, implicit, iterative, finite-difference scheme. The obtained results are checked against previously published work on special cases of the problem and are found to be in excellent agreement. A parametric study illustrating the influence of the thermal radiation coefficient, magnetic field, porous medium inertia parameter, concentration to thermal buoyancy ratio, and the Dufour and Soret numbers on the fluid velocity, temperature and concentration as well as the local Nusselt and the Sherwood numbers is conducted. The obtained results are shown graphically and the physical aspects of the problem are discussed.

Dulal Pal - One of the best experts on this subject based on the ideXlab platform.

  • Hall current and MHD effects on heat transfer over an unsteady stretching Permeable Surface with thermal radiation
    Computers & Mathematics with Applications, 2013
    Co-Authors: Dulal Pal
    Abstract:

    The influence of Hall current and thermal radiation on flow and heat transfer characteristics in a viscous fluid over an unsteady stretching Permeable Surface is studied in this paper. The unsteadiness in the flow and temperature fields is because of the time-dependent stretching velocity and Surface temperature. Similarity transformations are used to convert the governing time dependent nonlinear boundary layer equations for momentum and thermal energy to a system of nonlinear ordinary differential equations. These equations are solved numerically by applying shooting method using Runge-Kutta-Fehlberg method and analytically by differential transform method with Pade approximants (DTM-Pade). Comparison of the numerical results and analytical solutions (based on DTM-Pade approximant) is made with the earlier published results. The effects of the unsteadiness parameter, thermal radiation, Hall effects, suction/injection parameter and non-uniform heat source/sink parameter on flow and heat transfer characteristics as well as on the local Nusselt number are shown graphically.

  • combined effects of non uniform heat source sink and thermal radiation on heat transfer over an unsteady stretching Permeable Surface
    Communications in Nonlinear Science and Numerical Simulation, 2011
    Co-Authors: Dulal Pal
    Abstract:

    Abstract The present paper is concerned with the study of flow and heat transfer characteristics in the unsteady laminar boundary layer flow of an incompressible viscous fluid over continuously stretching Permeable Surface in the presence of a non-uniform heat source/sink and thermal radiation. The unsteadiness in the flow and temperature fields is because of the time-dependent stretching velocity and Surface temperature. Similarity transformations are used to convert the governing time-dependent nonlinear boundary layer equations for momentum and thermal energy are reduced to a system of nonlinear ordinary differential equations containing Prandtl number, non-uniform heat source/sink parameter, thermal radiation and unsteadiness parameter with appropriate boundary conditions. These equations are solved numerically by applying shooting method using Runge–Kutta–Fehlberg method. Comparison of numerical results is made with the earlier published results under limiting cases. The effects of the unsteadiness parameter, thermal radiation, suction/injection parameter, non-uniform heat source/sink parameter on flow and heat transfer characteristics as well as on the local Nusselt number are shown graphically.

  • Combined effects of non-uniform heat source/sink and thermal radiation on heat transfer over an unsteady stretching Permeable Surface
    Communications in Nonlinear Science and Numerical Simulation, 2011
    Co-Authors: Dulal Pal
    Abstract:

    Abstract The present paper is concerned with the study of flow and heat transfer characteristics in the unsteady laminar boundary layer flow of an incompressible viscous fluid over continuously stretching Permeable Surface in the presence of a non-uniform heat source/sink and thermal radiation. The unsteadiness in the flow and temperature fields is because of the time-dependent stretching velocity and Surface temperature. Similarity transformations are used to convert the governing time-dependent nonlinear boundary layer equations for momentum and thermal energy are reduced to a system of nonlinear ordinary differential equations containing Prandtl number, non-uniform heat source/sink parameter, thermal radiation and unsteadiness parameter with appropriate boundary conditions. These equations are solved numerically by applying shooting method using Runge–Kutta–Fehlberg method. Comparison of numerical results is made with the earlier published results under limiting cases. The effects of the unsteadiness parameter, thermal radiation, suction/injection parameter, non-uniform heat source/sink parameter on flow and heat transfer characteristics as well as on the local Nusselt number are shown graphically.

Ioan Pop - One of the best experts on this subject based on the ideXlab platform.

  • unsteady mixed convection flow of a nanofluid near orthogonal stagnation point on a vertical Permeable Surface
    Proceedings of the Institution of Mechanical Engineers Part E: Journal of Process Mechanical Engineering, 2014
    Co-Authors: Hossein Tamim, Saeed Dinarvand, Reza Hosseini, Sadegh Khalili, Ioan Pop
    Abstract:

    The unsteady mixed convection stagnation-point flow of a nanofluid toward a vertical Surface is investigated numerically. The external velocity impinges normal to the vertical Surface, the Surface temperature, and the Surface volume fraction of nanoparticles are assumed to vary linearly with the distance from the stagnation point. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. A similarity solution is presented, which depends on the Prandtl number Pr, Lewis number Le, Brownian motion number Nb, and thermophoresis number Nt. The governing system of equations is first transformed into a dimensionless form, and then the resulting equations are solved numerically by using a fourth-order Runge–Kutta scheme coupled with a conventional shooting procedure. The features of the flow, heat, and mass transfer characteristics for different values of the governing parameters are analyzed and discussed. Both assisting and opposing flows are considered. The quantitative c...

  • mhd mixed convection stagnation point flow of a nanofluid over a vertical Permeable Surface a comprehensive report of dual solutions
    Heat and Mass Transfer, 2014
    Co-Authors: Hossein Tamim, Saeed Dinarvand, Reza Hosseini, Ioan Pop
    Abstract:

    The steady laminar magnetohydrodynamic mixed convection boundary layer flow of a nanofluid near the stagnation-point on a vertical Permeable plate with prescribed external flow and Surface temperature is investigated in this study. Here, both assisting and opposing flows are considered and studied. Using appropriate similarity variables, the governing equations are transformed into nonlinear ordinary differential equations in the dimensionless stream function, which is solved numerically using the Runge–Kutta scheme coupled with a conventional shooting procedure. Three different types of nanoparticles, namely copper Cu, alumina Al2O3 and titania TiO2 with water as the base fluid are considered. Numerical results are obtained for the skin-friction coefficient and Nusselt number as well as for the velocity and temperature profiles for some values of the governing parameters, namely, the volume fraction of nanoparticles ϕ, permeability parameter f o , magnetic parameter M and mixed convection parameter λ. It is found that dual solutions exist for both assisting and opposing flows, and the range of the mixed convection parameter for which the solution exists, increases with suction, magnetic field and volume fraction of nanoparticles.

  • Unsteady mixed convection boundary-layer flow with suction and temperature slip effects near the stagnation point on a vertical Permeable Surface embedded in a porous medium
    Transport in Porous Media, 2012
    Co-Authors: Azizah Mohd Rohni, Ioan Pop, Syakila Ahmad, John H. Merkin
    Abstract:

    The unsteady mixed convection boundary-layer flow near the two-dimensional stagnation point on a vertical Permeable Surface embedded in a fluid-saturated porous medium with suction and a temperature slip effect is studied numerically. Similarity equations are obtained through the application of a similarity transformation technique. The shooting method is used to solve these similarity equations for different values of the mixed convection, wall mass suction, the unsteadiness and the slip parameters. Results show that multiple solutions exist for certain ranges of these parameters. Some limiting forms are then discussed, namely strong suction, the free convection limit, the situation when there is a large temperature slip and when the time dependence dominates.

  • mhd mixed convection flow near the stagnation point on a vertical Permeable Surface
    Physica A-statistical Mechanics and Its Applications, 2010
    Co-Authors: Anuar Mohd Ishak, Roslinda Mohd. Nazar, Norfifah Bachok, Ioan Pop
    Abstract:

    The steady magnetohydrodynamic (MHD) mixed convection boundary layer flow of a viscous and electrically conducting fluid near the stagnation-point on a vertical Permeable Surface is investigated in this study. The velocity of the external flow and the temperature of the plate Surface are assumed to vary linearly with the distance from the stagnation-point. The governing partial differential equations are first transformed into ordinary differential equations, before being solved numerically by a finite-difference method. The features of the flow and heat transfer characteristics for different values of the governing parameters are analyzed and discussed. Both assisting and opposing flows are considered. It is found that dual solutions exist for both cases, and the range of the mixed convection parameter for which the solution exists increases with suction.

  • the effects of transpiration on the flow and heat transfer over a moving Permeable Surface in a parallel stream
    Chemical Engineering Journal, 2009
    Co-Authors: Anuar Mohd Ishak, Roslinda Mohd. Nazar, Ioan Pop
    Abstract:

    The steady boundary layer flow over a moving Permeable sheet in a viscous and incompressible fluid is considered. In addition to the mass transfer from the plate (suction or injection), the viscous dissipation term is also included into the energy equation. The sheet is assumed to move in the same or opposite direction to the free stream. The governing partial differential equations are first transformed into ordinary differential equations before they are solved numerically by a finite-difference scheme. The numerical results are compared with known results from the open literature for some particular cases of the present study, to support their validity. The effects of the governing parameters on the flow and thermal fields are examined. The numerical results indicate that dual solutions exist when the sheet and the free stream move in the opposite directions. Moreover, compared to injection, suction increases the skin friction coefficient and the heat transfer rates at the Surface, besides delays the boundary layer separation.

Anuar Mohd Ishak - One of the best experts on this subject based on the ideXlab platform.

  • similarity solutions for flow and heat transfer over a Permeable Surface with convective boundary condition
    Applied Mathematics and Computation, 2010
    Co-Authors: Anuar Mohd Ishak
    Abstract:

    Abstract The steady laminar boundary layer flow over a Permeable flat plate in a uniform free stream, with the bottom Surface of the plate is heated by convection from a hot fluid is considered. Similarity solutions for the flow and thermal fields are possible if the mass transpiration rate at the Surface and the convective heat transfer from the hot fluid on the lower Surface of the plate vary like x −1/2 , where x is the distance from the leading edge of the solid Surface. The governing partial differential equations are first transformed into ordinary differential equations, before being solved numerically. The effects of the governing parameters on the flow and thermal fields are thoroughly examined and discussed.

  • mhd mixed convection flow near the stagnation point on a vertical Permeable Surface
    Physica A-statistical Mechanics and Its Applications, 2010
    Co-Authors: Anuar Mohd Ishak, Roslinda Mohd. Nazar, Norfifah Bachok, Ioan Pop
    Abstract:

    The steady magnetohydrodynamic (MHD) mixed convection boundary layer flow of a viscous and electrically conducting fluid near the stagnation-point on a vertical Permeable Surface is investigated in this study. The velocity of the external flow and the temperature of the plate Surface are assumed to vary linearly with the distance from the stagnation-point. The governing partial differential equations are first transformed into ordinary differential equations, before being solved numerically by a finite-difference method. The features of the flow and heat transfer characteristics for different values of the governing parameters are analyzed and discussed. Both assisting and opposing flows are considered. It is found that dual solutions exist for both cases, and the range of the mixed convection parameter for which the solution exists increases with suction.

  • the effects of transpiration on the flow and heat transfer over a moving Permeable Surface in a parallel stream
    Chemical Engineering Journal, 2009
    Co-Authors: Anuar Mohd Ishak, Roslinda Mohd. Nazar, Ioan Pop
    Abstract:

    The steady boundary layer flow over a moving Permeable sheet in a viscous and incompressible fluid is considered. In addition to the mass transfer from the plate (suction or injection), the viscous dissipation term is also included into the energy equation. The sheet is assumed to move in the same or opposite direction to the free stream. The governing partial differential equations are first transformed into ordinary differential equations before they are solved numerically by a finite-difference scheme. The numerical results are compared with known results from the open literature for some particular cases of the present study, to support their validity. The effects of the governing parameters on the flow and thermal fields are examined. The numerical results indicate that dual solutions exist when the sheet and the free stream move in the opposite directions. Moreover, compared to injection, suction increases the skin friction coefficient and the heat transfer rates at the Surface, besides delays the boundary layer separation.

  • MHD Flow Towards a Permeable Surface with Prescribed Wall Heat Flux
    Chinese Physics Letters, 2009
    Co-Authors: Anuar Mohd Ishak, Roslinda Mohd. Nazar, Ioan Pop
    Abstract:

    The steady magnetohydrodynamic (MHD) mixed convection flow towards a vertical Permeable Surface with prescribed heat flux is investigated. The governing partial differential equations are transformed into a system of ordinary differential equations, which is then solved numerically by a finite-difference method. The features of the flow and heat transfer characteristics for different values of the governing parameters are analysed and discussed. Both assisting and opposing flows are considered. It is found that dual solutions exist for the assisting flow, besides the solutions usually reported in the literature for the opposing fow.

  • Heat transfer over an unsteady stretching Permeable Surface with prescribed wall temperature
    Nonlinear Analysis: Real World Applications, 2009
    Co-Authors: Anuar Mohd Ishak, Roslinda Mohd. Nazar, Ioan Pop
    Abstract:

    The unsteady laminar boundary layer flow over a continuously stretching Permeable Surface is investigated. The unsteadiness in the flow and temperature fields is caused by the time-dependence of the stretching velocity and the Surface temperature. Effects of the unsteadiness parameter, suction/injection parameter and Prandtl number on the heat transfer characteristics are thoroughly examined.

M M Rashidi - One of the best experts on this subject based on the ideXlab platform.

  • entropy analysis for an unsteady mhd flow past a stretching Permeable Surface in nano fluid
    Powder Technology, 2014
    Co-Authors: Mohammad Hossein Abolbashari, Foad Nazari, Navid Freidoonimehr, M M Rashidi
    Abstract:

    Abstract In this article we employ homotopy analysis method (HAM), to study the entropy analysis in an unsteady magneto-hydrodynamic nano-fluid regime adjacent to an accelerating stretching Permeable Surface with the water as the base fluid and four different types of nanoparticles; copper (Cu), copper oxide (CuO), aluminum oxide (Al 2 O 3 ) and titanium dioxide (TiO 2 ). The governing partial differential equations are transformed into highly nonlinear coupled ordinary differential equations consisting of the momentum and energy equations via appropriate similarity transformations. The current HAM solution demonstrates very good correlation with those of the previously published studies in the especial cases. The influences of different flow physical parameters such as the nanoparticle volume fraction parameter ( φ ), unsteadiness parameter ( A ), magnetic parameter ( M ), suction parameter ( f w ), and different types of nanoparticles on the fluid velocity component ( f ′( η )), the temperature distribution ( θ ( η )), the skin friction coefficient ( C f Re x 1/2 ), the local Nusselt number ( Nu x / Re x 1/2 ), and the averaged entropy generation function ( N G , av ) and also the effects of the Reynolds ( Re ) number, the Brinkman number ( Br ) and the Hartmann number ( Ha ) on the averaged entropy generation function ( N G , av ) are illustrated graphically and discussed in details. This model has important applications in heat transfer enhancement in the renewable energy systems, industrial thermal management and also materials processing.