A.M. Rashad

Non-Darcy natural convection flow for non-Newtonian nanofluid over cone saturated in porous medium with uniform heat and volume fraction fluxes

Purpose – The purpose of this paper is to investigate the effect of uniform lateral mass flux on non-Darcy natural convection of non-Newtonian fluid along a vertical cone embedded in a porous medium filled with a nanofluid. Design/methodology/approach – The resulting governing equations are non-dimensionalized and transformed into a non-similar form and then solved numerically by Keller box finite-difference method. Findings – A comparison with previously published works is performed and excellent agreement is obtained. Research limitations/implications – The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. It is assumed that the cone surface is preamble for possible nanofluid wall suction/injection, under the condition of uniform heat and nanoparticles volume fraction fluxes. Originality/value – The effects of nanofluid parameters, Ergun number, surface mass flux and viscosity index are investigated on the velocity, temperature, and volume fraction profiles as ...

Natural convection from a vertical permeable cone in a nanofluid saturated porous media for uniform heat and nanoparticles volume fraction fluxes

Purpose – The purpose of this paper is to study steady, laminar, natural convection boundary‐layer flow over a permeable vertical cone embedded in a porous medium saturated with a nanofluid in the presence of uniform lateral mass flux.Design/methodology/approach – The paper studies steady, laminar, natural convection boundary‐layer flow over a permeable vertical cone embedded in a porous medium saturated with a nanofluid in the presence of uniform lateral mass flux.Findings – The presence of nanoparticles has significant effects of heat transfer.Originality/value – The area of nanofluids is very original.

Radiation Effects on Mixed Convection over a Wedge Embedded in a Porous Medium Filled with a Nanofluid

The problem of steady, laminar, mixed convection boundary-layer flow over an isothermal vertical wedge embedded in a porous medium saturated with a nanofluid is studied, in the presence of thermal radiation. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis with Rosseland diffusion approximation. The wedge surface is maintained at a constant temperature and a constant nanoparticle volume fraction. The resulting governing equations are non-dimensionalized and transformed into a non-similar form and then solved by Keller box method. A comparison is made with the available results in the literature, and our results are in very good agreement with the known results. A parametric study of the physical parameters is made, and a representative set of numerical results for the velocity, temperature, and volume fraction, the local Nusselt and Sherwood numbers are presented graphically. The salient features of the results are analyzed and discussed.

Natural convection boundary layer of a non-Newtonian fluid about a permeable vertical cone embedded in a porous medium saturated with a nanofluid

An analysis was performed to study the effect of uniform transpiration velocity on free convection boundary-layer flow of a non-Newtonian fluid over a permeable vertical cone embedded in a porous medium saturated with a nanofluid. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. The governing partial differential equations are transformed into a set of non-similar equations and solved numerically by an efficient implicit, iterative, finite-difference method. Comparisons with previously published work are performed and excellent agreement is obtained. A parametric study of the physical parameters is conducted and a representative set of numerical results for the velocity, temperature, and volume fraction profiles as well as the local Nusselt and Sherwood numbers is illustrated graphically to show interesting features of the solutions.

Radiation effects on mixed convection about a cone embedded in a porous medium filled with a nanofluid

The problem of steady, laminar, mixed convection boundary-layer flow over a vertical cone embedded in a porous medium saturated with a nanofluid is studied, in the presence of thermal radiation. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis with Rosseland diffusion approximation. The cone surface is maintained at a constant temperature and a constant nanoparticle volume fraction. The resulting governing equations are non-dimensionalized and transformed into a non-similar form and then solved by Keller box method. A comparison is made with the available results in the literature, and our results are in very good agreement with the known results. A parametric study of the physical parameters is made and a representative set of numerical results for the local Nusselt and Sherwood numbers are presented graphically. Also, the salient features of the results are analyzed and discussed.

Boundary-Layer Heat Transfer from a Stretching Circular Cylinder in a Nanofluid

DB = Brownian diffusion coefficient DT = thermophoretic diffusion coefficient f = reduced stream function g = gravitational acceleration K = permeability of porous medium km = effective thermal conductivity Le = Lewis number Nb = Brownian motion parameters Nt = thermophoresis parameters Nu = Nusselt number p = pressure q = wall heat flux Re = Reynolds number r; z = Cartesian coordinates S = shear stress T = temperature Tw = wall temperature of the vertical plate T1 = ambient temperature u, w = Darcy velocity components m = thermal diffusivity of porous medium = dimensionless distance = dimensionless temperature = viscosity of fluid = kinematic viscosity f = fluid density p = nanoparticle mass density c f = heat capacity of the fluid c m = effective heat capacity c p = effective heat capacity of nanoparticle material = ratio between the effective heat capacity of the nanoparticle material and that of the fluid Subscripts

Unsteady MHD combined convection over a moving vertical sheet in a fluid saturated porous medium with uniform surface heat flux

The group transformation method is applied for solving the combined convection problem in an unsteady, two-dimensional, laminar, boundary-layer flow of a viscous, incompressible and electrically-conducting fluid along a vertical continuous moving plate saturated porous medium in the presence of a uniform transverse magnetic field. The uniform surface heat flux boundary condition is considered. The application of two-parameter groups reduces the number of independent variables by two and consequently the system of governing partial differential equations reduces to a system of ordinary differential equations with appropriate boundary conditions. The ordinary differential equations are solved numerically using a shooting method. A discussion is provided for the effect of magnetic parameter M, permeability of the porous medium k and Prandtl number, Pr, on the velocity and temperature fields within the boundary layer and on shear stress and heat transfer.

Melting Effect on Unsteady Hydromagnetic Flow of a Nanofluid Past a Stretching Sheet

This paper considers unsteady, laminar, boundary-layer flow with heat and mass transfer of a nanofluid along a horizontal stretching plate in the presence of a transverse magnetic field, melting and heat generation or absorption effects. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. The governing partial differential equations are transformed into a set of non-similar equations and solved numerically by an efficient implicit, iterative, finite-difference method. A parametric study illustrating the influence of various physical parameters is performed. Numerical results for the steady-state velocity, temperature and nanoparticles volume fraction profiles as well as the time histories of the skin-friction coefficient, Nusselt number and the Sherwood number are presented graphically and discussed.

Effect of chemical reaction on heat and mass transfer by mixed convection flow about a sphere in a saturated porous media

Purpose – The purpose of this paper is to study the effects of chemical reaction on mixed convection flow along a sphere in non‐Darcian porous media.Design/methodology/approach – The sphere surface is maintained at uniform temperature and species concentration for both cases of heated (assisting flow) and cooled (opposing flow) sphere. An appropriate transformation is employed and the transformed equations are solved numerically using an efficient implicit iterative tri‐diagonal finite difference method.Findings – It is found that chemical reactions have significant effect on heat and mass transfer. Comparisons with previously published work are performed and the results are found to be in excellent agreement.Originality/value – The paper is original and describes how a parametric study of the physical parameters was conducted and illustrates graphically a representative set of numerical results for the velocity, temperature, and concentration profiles, as well as the local skin‐friction coefficient, loca...

Effects of heat sink and source and entropy generation on MHD mixed convection of a Cu-water nanofluid in a lid-driven square porous enclosure with partial slip

In this work, the effects of the presence of a heat sink and a heat source and their lengths and locations and the entropy generation on MHD mixed convection flow and heat transfer in a porous enclosure filled with a Cu-water nanofluid in the presence of partial slip effect are investigated numerically. Both the lid driven vertical walls of the cavity are thermally insulated and are moving with constant and equal speeds in their own plane and the effect of partial slip is imposed on these walls. A segment of the bottom wall is considered as a heat source meanwhile a heat sink is placed on the upper wall of cavity. There are heated and cold parts placed on the bottom and upper walls, respectively, while the remaining parts are thermally insulated. Entropy generation and local heat transfer according to different values of the governing parameters are presented in detail. It is found that the addition of nanoparticles decreases the convective heat transfer inside the porous cavity at all ranges of the heat ...