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

  • effects of partial slip on entropy generation and mhd Combined Convection in a lid driven porous enclosure saturated with a cu water nanofluid
    Journal of Thermal Analysis and Calorimetry, 2018
    Co-Authors: A M Rashad, Ali J. Chamkha, T Armaghani, M. A. Mansour
    Abstract:

    In this work, the influences of heat generation/absorption and nanofluid volume fraction on the entropy generation and MHD Combined Convection heat transfer in a porous enclosure filled with a Cu–water nanofluid are studied numerically with of partial slip effect. The finite volume technique is utilized to solve the dimensionless equations governing the problem. A comparison with already published studies is conducted, and the data are found to be in an excellent agreement. The minimization of entropy generation and the local heat transfer according to various values of the controlling parameters are reported in detail. The outcome indicates that an augmentation in the heat generation/absorption parameter decreases the Nusselt number. Also, when the volume fraction is raised, the Nusselt number and entropy generation are reduced. The impact of Hartmann number on heat transfer and the Richardson number on the entropy generation and the thermal rendering criteria are also presented and discussed.

  • A finite element analysis on Combined Convection and conduction in a channel with a thick walled cavity
    International Journal of Numerical Methods for Heat & Fluid Flow, 2014
    Co-Authors: Mustafizur Rahman, Hakan F Oztop, Saad Mekhilef, Rahman Saidur, Ali J. Chamkha, Amimul Ahsan, Khaled Al-salem
    Abstract:

    Purpose – The purpose of this paper is to examine the effects of thick wall parameters of a cavity on Combined Convection in a channel. In other words, conjugate heat transfer is solved. Design/methodology/approach – Galerkin weighted residual finite element method is used to solve the governing equations of mixed Convection. Findings – The streamlines, isotherms, local and average Nusselt numbers are obtained and presented for different parameters. It is found heat transfer is an increasing function of dimensionless thermal conductivity ratio. Originality/value – The literature does not have mixed Convection and conjugate heat transfer problem in a channel with thick walled cavity.

  • Combined Convection flow in triangular wavy chamber filled with water cuo nanofluid effect of viscosity models
    International Communications in Heat and Mass Transfer, 2012
    Co-Authors: Rehena Nasrin, M A Alim, Ali J. Chamkha
    Abstract:

    Abstract This work is focused on the numerical modeling of steady laminar Combined Convection flow in a vertical triangular wavy enclosure filled with water–CuO nanofluid. The left and right vertical walls of the cavity take the form of a triangular wavy pattern. The bottom and top horizontal walls are mechanically driven. The lower and upper surfaces move to the right and left direction at the same constant speed respectively. They maintain constant temperature lower than both vertical walls. Two different nanofluid models namely, the Brinkman model and the Pak and Cho correlation are employed. The developed equations are given in terms of the Navier Stokes and the energy equation and are non-dimensionalized and then solved numerically subject to appropriate boundary conditions by the Galerkin's finite-element method. Comparisons with published work are performed and found to be in good agreement. A parametric study is conducted and a selective set of graphical results is presented. The effects of the Reynolds number, Richardson number and the nanoparticles volume fraction on the flow and heat transfer characteristics in the cavity are displayed to compare the predictions obtained by the two different nanofluid models. Heat transfer enhancement can be obtained significantly due to the presence of nanoparticles. The rate of heat transfer is accentuated moderately by falling the Richardson number and rising the Reynolds number as well as the solid volume fraction.

  • Combined Convection flow in triangular wavy chamber filled with water–CuO nanofluid: Effect of viscosity models
    International Communications in Heat and Mass Transfer, 2012
    Co-Authors: Rehena Nasrin, M A Alim, Ali J. Chamkha
    Abstract:

    Abstract This work is focused on the numerical modeling of steady laminar Combined Convection flow in a vertical triangular wavy enclosure filled with water–CuO nanofluid. The left and right vertical walls of the cavity take the form of a triangular wavy pattern. The bottom and top horizontal walls are mechanically driven. The lower and upper surfaces move to the right and left direction at the same constant speed respectively. They maintain constant temperature lower than both vertical walls. Two different nanofluid models namely, the Brinkman model and the Pak and Cho correlation are employed. The developed equations are given in terms of the Navier Stokes and the energy equation and are non-dimensionalized and then solved numerically subject to appropriate boundary conditions by the Galerkin's finite-element method. Comparisons with published work are performed and found to be in good agreement. A parametric study is conducted and a selective set of graphical results is presented. The effects of the Reynolds number, Richardson number and the nanoparticles volume fraction on the flow and heat transfer characteristics in the cavity are displayed to compare the predictions obtained by the two different nanofluid models. Heat transfer enhancement can be obtained significantly due to the presence of nanoparticles. The rate of heat transfer is accentuated moderately by falling the Richardson number and rising the Reynolds number as well as the solid volume fraction.

  • hydromagnetic Combined Convection flow in a vertical lid driven cavity with internal heat generation or absorption
    Numerical Heat Transfer Part A-applications, 2002
    Co-Authors: Ali J. Chamkha
    Abstract:

    The problem of unsteady, laminar, Combined forced-free Convection flow in a square cavity in the presence of internal heat generation or absorption and a magnetic field is formulated. Both the top and bottom horizontal walls of the cavity are insulated while the left and right vertical walls are kept at constant and different temperatures. The left vertical wall is moving in its own plane at a constant speed while all other walls are fixed. A uniform magnetic field is applied in the horizontal direction normal to the moving wall. A temperature-dependent heat source or sink is assumed to exist within the cavity. The governing equations and conditions are solved numerically by the finite-volume approach along with the alternating direct implicit (ADI) procedure. Two cases of thermal boundary conditions corresponding to aiding and opposing flows are considered. Comparisons with previously published work are performed and the results are found to be in excellent agreement. A parametric study is conducted and ...

Rehena Nasrin - One of the best experts on this subject based on the ideXlab platform.

  • Combined Convection flow in triangular wavy chamber filled with water cuo nanofluid effect of viscosity models
    International Communications in Heat and Mass Transfer, 2012
    Co-Authors: Rehena Nasrin, M A Alim, Ali J. Chamkha
    Abstract:

    Abstract This work is focused on the numerical modeling of steady laminar Combined Convection flow in a vertical triangular wavy enclosure filled with water–CuO nanofluid. The left and right vertical walls of the cavity take the form of a triangular wavy pattern. The bottom and top horizontal walls are mechanically driven. The lower and upper surfaces move to the right and left direction at the same constant speed respectively. They maintain constant temperature lower than both vertical walls. Two different nanofluid models namely, the Brinkman model and the Pak and Cho correlation are employed. The developed equations are given in terms of the Navier Stokes and the energy equation and are non-dimensionalized and then solved numerically subject to appropriate boundary conditions by the Galerkin's finite-element method. Comparisons with published work are performed and found to be in good agreement. A parametric study is conducted and a selective set of graphical results is presented. The effects of the Reynolds number, Richardson number and the nanoparticles volume fraction on the flow and heat transfer characteristics in the cavity are displayed to compare the predictions obtained by the two different nanofluid models. Heat transfer enhancement can be obtained significantly due to the presence of nanoparticles. The rate of heat transfer is accentuated moderately by falling the Richardson number and rising the Reynolds number as well as the solid volume fraction.

  • Combined Convection flow in triangular wavy chamber filled with water–CuO nanofluid: Effect of viscosity models
    International Communications in Heat and Mass Transfer, 2012
    Co-Authors: Rehena Nasrin, M A Alim, Ali J. Chamkha
    Abstract:

    Abstract This work is focused on the numerical modeling of steady laminar Combined Convection flow in a vertical triangular wavy enclosure filled with water–CuO nanofluid. The left and right vertical walls of the cavity take the form of a triangular wavy pattern. The bottom and top horizontal walls are mechanically driven. The lower and upper surfaces move to the right and left direction at the same constant speed respectively. They maintain constant temperature lower than both vertical walls. Two different nanofluid models namely, the Brinkman model and the Pak and Cho correlation are employed. The developed equations are given in terms of the Navier Stokes and the energy equation and are non-dimensionalized and then solved numerically subject to appropriate boundary conditions by the Galerkin's finite-element method. Comparisons with published work are performed and found to be in good agreement. A parametric study is conducted and a selective set of graphical results is presented. The effects of the Reynolds number, Richardson number and the nanoparticles volume fraction on the flow and heat transfer characteristics in the cavity are displayed to compare the predictions obtained by the two different nanofluid models. Heat transfer enhancement can be obtained significantly due to the presence of nanoparticles. The rate of heat transfer is accentuated moderately by falling the Richardson number and rising the Reynolds number as well as the solid volume fraction.

  • Joule Heating Effect on MHD Combined Convection in a Wavy Chamber Having Conducting Square Cylinder
    Journal of Scientific Research, 2011
    Co-Authors: Rehena Nasrin
    Abstract:

    The current simulation is focused on MHD Combined Convection flow and heat transfer characteristics in a square lid driven chamber. At the centre of this chamber a heat conducting solid square cylinder is located. Galerkin weighted residual finite element method is used to solve the governing equations of mass, momentum and energy. The left vertical wall of the chamber is mechanically lid driven and having temperature T cold and velocity V 0 .  But the right wall is sinusoidal wavy pattern and contains more temperature ( T hot ) than the left lid. The top and bottom surfaces are adiabatic. The behavior of the fluid for the values of Joule heating parameter J (0, 1, 4, 7) and Richardson number Ri (0.1, 1, 10) is described in details. The variations of the average Nusselt number ( Nu ), the mean temperature of the fluid ( ) and the temperature at cylinder centre ( ) for various Ri and J are also presented. Maximum rate of heat transfer is occurred for the lowest J at each Ri . Keywords: MHD; Wavy chamber; Conducting cylinder; Combined Convection; Finite element formulation. © 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v4i1.8014 J. Sci. Res. 4 (1), 39-49 (2012)

  • Influence of centered conducting obstacle on MHD Combined Convection in a wavy chamber
    Journal of Naval Architecture and Marine Engineering, 2011
    Co-Authors: Rehena Nasrin
    Abstract:

    The development of centered heat conducting obstacle effect on Combined magnetoconvective flow in a lid driven chamber has been numerically studied. The enclosure considered has rectangular horizontal lower surfaces and vertical side surfaces. The lower and upper surfaces are insulated. The left wall is mechanically lid driven having uniform temperature Ti and velocity v0 while other vertical side is wavy and maintains higher temperature Th than the lid. The governing two-dimensional flow equations have been solved by using Galerkin weighted residual finite element technique. The investigations are conducted for different values of Richardson number (Ri) and physical parameter i.e. diameter (D) of square solid body. Various characteristics such as streamlines, isotherms and heat transfer rate in terms of the mean Nusselt number (Nu), the average temperature (?av) of the fluid and temperature of obstacle center (?c) are presented. The results indicate that the mentioned parameters strongly affect the flow phenomenon and temperature field inside the chamber. Conducting largest obstacle is preferable for effective heat transfer mechanism in presence of magnetic field. Keywords: Combined Convection, MHD, wavy chamber, heat conducting obstacle, finite element simulation. doi: http://dx.doi.org/10.3329/jname.v8i2.7392 Journal of Naval Architecture and Marine Engineering 8(2011) 93-104

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

  • Combined Convection flow in triangular wavy chamber filled with water cuo nanofluid effect of viscosity models
    International Communications in Heat and Mass Transfer, 2012
    Co-Authors: Rehena Nasrin, M A Alim, Ali J. Chamkha
    Abstract:

    Abstract This work is focused on the numerical modeling of steady laminar Combined Convection flow in a vertical triangular wavy enclosure filled with water–CuO nanofluid. The left and right vertical walls of the cavity take the form of a triangular wavy pattern. The bottom and top horizontal walls are mechanically driven. The lower and upper surfaces move to the right and left direction at the same constant speed respectively. They maintain constant temperature lower than both vertical walls. Two different nanofluid models namely, the Brinkman model and the Pak and Cho correlation are employed. The developed equations are given in terms of the Navier Stokes and the energy equation and are non-dimensionalized and then solved numerically subject to appropriate boundary conditions by the Galerkin's finite-element method. Comparisons with published work are performed and found to be in good agreement. A parametric study is conducted and a selective set of graphical results is presented. The effects of the Reynolds number, Richardson number and the nanoparticles volume fraction on the flow and heat transfer characteristics in the cavity are displayed to compare the predictions obtained by the two different nanofluid models. Heat transfer enhancement can be obtained significantly due to the presence of nanoparticles. The rate of heat transfer is accentuated moderately by falling the Richardson number and rising the Reynolds number as well as the solid volume fraction.

  • Combined Convection flow in triangular wavy chamber filled with water–CuO nanofluid: Effect of viscosity models
    International Communications in Heat and Mass Transfer, 2012
    Co-Authors: Rehena Nasrin, M A Alim, Ali J. Chamkha
    Abstract:

    Abstract This work is focused on the numerical modeling of steady laminar Combined Convection flow in a vertical triangular wavy enclosure filled with water–CuO nanofluid. The left and right vertical walls of the cavity take the form of a triangular wavy pattern. The bottom and top horizontal walls are mechanically driven. The lower and upper surfaces move to the right and left direction at the same constant speed respectively. They maintain constant temperature lower than both vertical walls. Two different nanofluid models namely, the Brinkman model and the Pak and Cho correlation are employed. The developed equations are given in terms of the Navier Stokes and the energy equation and are non-dimensionalized and then solved numerically subject to appropriate boundary conditions by the Galerkin's finite-element method. Comparisons with published work are performed and found to be in good agreement. A parametric study is conducted and a selective set of graphical results is presented. The effects of the Reynolds number, Richardson number and the nanoparticles volume fraction on the flow and heat transfer characteristics in the cavity are displayed to compare the predictions obtained by the two different nanofluid models. Heat transfer enhancement can be obtained significantly due to the presence of nanoparticles. The rate of heat transfer is accentuated moderately by falling the Richardson number and rising the Reynolds number as well as the solid volume fraction.

Aldo Steinfeld - One of the best experts on this subject based on the ideXlab platform.

  • high temperature thermal storage using a packed bed of rocks heat transfer analysis and experimental validation
    Applied Thermal Engineering, 2011
    Co-Authors: Markus Hanchen, Sarah Bruckner, Aldo Steinfeld
    Abstract:

    High-temperature thermal storage in a packed bed of rocks is considered for air-based concentrated solar power plants. The unsteady 1D two-phase energy conservation equations are formulated for Combined Convection and conduction heat transfer, and solved numerically for charging/discharging cycles. Validation is accomplished in a pilot-scale experimental setup with a packed bed of crushed steatite (magnesium silicate rock) at 800 K. A parameter study of the packed bed dimensions, fluid flow rate, particle diameter, and solid phase material was carried out to evaluate the charging/discharging characteristics, daily cyclic operation, overall thermal efficiency and capacity ratio.

Hakan F Oztop - One of the best experts on this subject based on the ideXlab platform.

  • A finite element analysis on Combined Convection and conduction in a channel with a thick walled cavity
    International Journal of Numerical Methods for Heat & Fluid Flow, 2014
    Co-Authors: Mustafizur Rahman, Hakan F Oztop, Saad Mekhilef, Rahman Saidur, Ali J. Chamkha, Amimul Ahsan, Khaled Al-salem
    Abstract:

    Purpose – The purpose of this paper is to examine the effects of thick wall parameters of a cavity on Combined Convection in a channel. In other words, conjugate heat transfer is solved. Design/methodology/approach – Galerkin weighted residual finite element method is used to solve the governing equations of mixed Convection. Findings – The streamlines, isotherms, local and average Nusselt numbers are obtained and presented for different parameters. It is found heat transfer is an increasing function of dimensionless thermal conductivity ratio. Originality/value – The literature does not have mixed Convection and conjugate heat transfer problem in a channel with thick walled cavity.

  • fluid flow due to Combined Convection in lid driven enclosure having a circular body
    International Journal of Heat and Fluid Flow, 2009
    Co-Authors: Hakan F Oztop, Zepu Zhao, Bo Yu
    Abstract:

    Abstract The present work is aimed to study mixed Convection heat transfer characteristics for a lid-driven air flow within a square enclosure having a circular body. Flows are driven by the left lid, which slides in its own plane constant velocity. This wall is isothermal and it moves up or down in y direction while the other walls remain stationary. The horizontal walls are adiabatic. The cavity is differentially heated and the left wall is maintained at a higher temperature than the right wall. Three different temperature boundary conditions were applied for the inner cylinder as adiabatic, isothermal or conductive. The computation is carried out for wide ranges of Richardson numbers, diameter of inner cylinder and center and location of the inner cylinder. It was found that the most effective parameter on flow field and temperature distribution is the orientation of the moving lid. The circular body can be a control parameter for heat and fluid flow. An interesting obtained result that the thermal conductivity becomes insignificant for small values of diameter of the circular body.

  • Combined Convection in inclined porous lid driven enclosures with sinusoidal thermal boundary condition on one wall
    Progress in Computational Fluid Dynamics, 2009
    Co-Authors: Hakan F Oztop, Asaf Varol
    Abstract:

    A numerical study has been performed to obtain Combined Convection field in an inclined porous lid-driven enclosures heated from one wall with a non-uniformly heater. The lid moves at constant speed and temperature. Darcy-Brinkman-Forchheimer model was adopted to write governing equations and they solved using finite volume method. A detailed parametric study has been presented for different Reynolds numbers (10 ≤ Re ≤ 1000), Grashof numbers (104 ≤ Gr ≤ 105), Darcy numbers (0.01 ≤ Da ≤ 0.1), porosity (0.6 ≤ e ≤ 0.9) and inclination angle of enclosure (0° ≤ φ ≤ 180°). It is observed that flow field, temperature distribution and heat transfer are affected by inclination angle of the enclosure.

  • Combined Convection heat transfer in a porous lid driven enclosure due to heater with finite length
    International Communications in Heat and Mass Transfer, 2006
    Co-Authors: Hakan F Oztop
    Abstract:

    A numerical work is performed to analyze Combined Convection heat transfer and fluid flow in a partially heated porous lid-driven enclosure. The top wall of enclosure moves from left to right with constant velocity and temperature. Heater with finite length is located on the fixed wall where its center of location changes along the walls. The finite volume-based finite-difference method is applied for numerical experiments. Parameters effective on flow and thermal fields are Richardson number, Darcy number, center of heater and heater length. The results are shown that the best heat transfer is formed when the heater is located on the left vertical wall.