Mohamed A. Mansour, Mohamed M. Abd‐Elaziz, Ramadan Abdalla and Sameh Elsayed
The purpose of this paper is to deal with unsteady double diffusive natural convection in a square enclosure filled with a porous medium with various boundary condition effects in…
Abstract
Purpose
The purpose of this paper is to deal with unsteady double diffusive natural convection in a square enclosure filled with a porous medium with various boundary condition effects in the presence of heat source or sink.
Design/methodology/approach
Finite difference method was employed to solve the dimensionless governing equations of the problem. The effects of governing parameters, namely, amplitude wave length ratio, dimensionless time parameter, Darcy number, buoyancy parameter and heat generation/absorption parameter on the streamlines, temperature and concentration contours, as well as Nusselt number and Sherwood number, were considered.
Findings
The sinusoidal variations of the temperature and concentration remove the singularities which appear in the case of fixed temperature and concentration.
Originality/value
The paper's results are validated by favorable comparisons with previously published results. The results of the problem are presented in graphical and tabular forms and discussed.
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Mohamed I.A. Othman and Elsayed M. Abd-Elaziz
The purpose of this study is to obtain a general solution to the field equations of thermoelastic solid with voids and micro-temperatures under the gravitational field in the…
Abstract
Purpose
The purpose of this study is to obtain a general solution to the field equations of thermoelastic solid with voids and micro-temperatures under the gravitational field in the context of the three theories, namely, coupled theory (CT), Lord and Shulman theory and Green and Lindsay theory.
Design/methodology/approach
The normal mode analysis is used to obtain the exact expressions for the considered variables. Comparisons are made with the results obtained in the three theories with and without gravity. Some particular cases are also deduced from the present investigation.
Findings
The effect of the gravity on the displacement, the micro-temperature vector, the temperature distribution, the normal stress, the changes in the volume fraction field and the heat flux moments have been depicted graphically.
Research limitations/implications
Some particular cases are also deduced from the present investigation.
Originality/value
The results of the physical quantities have been illustrated graphically by a comparison between three different theories in the presence and absence of gravity.
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Samia M. Said, Mohamed I.A. Othman and Mohamed G. Eldemerdash
In the present article, the three-phase-lag (3PHL) model and the Green-Naghdi theory of types II, III with memory-dependent derivative is used to study the effect of rotation on a…
Abstract
Purpose
In the present article, the three-phase-lag (3PHL) model and the Green-Naghdi theory of types II, III with memory-dependent derivative is used to study the effect of rotation on a nonlocal porous thermoelastic medium.
Design/methodology/approach
In this study normal mode analysis is used to obtain analytical expressions of the physical quantities. The numerical results are given and presented graphically when mechanical force is applied.
Findings
The model is illustrated in the context of the Green-Naghdi theory of types II, III and the three-phase lags model. Expressions for the physical quantities are solved by using the normal mode analysis and represented graphically.
Originality/value
Comparisons are made with the results predicted in the absence and presence of the rotation as well as a nonlocal parameter. Also, the comparisons are made with the results of the 3PHL model for different values of time delay.
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Samy Shaban, Abd Elaziz Fouda, Mohamed Elmorsi, Tarek Fayed and Omar Azazy
The purpose of this study is to inspect the corrosion inhibition of API N80 steel pipelines in uninhibited solution and inhibited with a synthesized surfactant compound…
Abstract
Purpose
The purpose of this study is to inspect the corrosion inhibition of API N80 steel pipelines in uninhibited solution and inhibited with a synthesized surfactant compound [N-(3-(dimethyl octyl ammonio) propyl) palmitamide bromide] (DMDPP), which is prepared through a simple and applicable method.
Design/methodology/approach
Weight loss was inspected at five different temperatures of 25°C, 30°C, 40°C, 50°C and 60°C Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation were used at room temperature. Density functional theory was used to study the relation between the molecular structure and inhibition theoretically.
Findings
Adsorption of the prepared DMDPP fits the Langmuir isotherm model. The inhibition efficiency of the prepared DMDPP amphipathic inhibitor is directly proportional to temperature increase. Polarization results reveal that the investigated DMDPP amphipathic compound behaves as a mixed-type inhibitor. EIS spectra produced one individual capacitive loop.
Originality/value
The originality is the preparation of cationic surfactants through a simple method, which can be used as corrosion inhibitors in oil production. The synthesized inhibitors were prepared from low-price materials. The work studied the behavior of the synthesized surfactants in inhibiting the corrosion of the steel in an acidic medium. Electrochemical and theoretical studies were presented, besides gravimetric and surface examination.
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Abdeslam Omara, Mouna Touiker and Abderrahim Bourouis
This paper aims to consider numerical analysis of laminar double-diffusive natural convection inside a non-homogeneous closed medium composed of a saturated porous matrix and a…
Abstract
Purpose
This paper aims to consider numerical analysis of laminar double-diffusive natural convection inside a non-homogeneous closed medium composed of a saturated porous matrix and a clear binary fluid under spatial sinusoidal heating/cooling on one side wall and uniform salting.
Design/methodology/approach
The domain of interest is a partially square porous enclosure with sinusoidal wall heating and cooling. The fluid flow, heat and mass transfer dimensionless governing equations associated with the corresponding boundary conditions are discretized using the finite volume method. The resulting algebraic equations are solved by an in-house FORTRAN code and the SIMPLE algorithm to handle the non-linear character of conservation equations. The validity of the in-house FORTRAN code is checked by comparing the current results with previously published experimental and numerical works. The effect of the porous layer thickness, the spatial frequency of heating and cooling, the Darcy number, the Rayleigh number and the porous to fluid thermal conductivity ratio is analyzed.
Findings
The results demonstrate that for high values of the spatial frequency of heating and cooling (f = 7), temperature contours show periodic variations with positive and negative values providing higher temperature gradient near the thermally active wall. In this case, the temperature variation is mainly in the porous layer, while the temperature of the clear fluid region is practically the same as that imposed on the left vertical wall. This aspect can have a beneficial impact on thermal insulation. Besides, the porous to fluid thermal conductivity ratio,
Practical implications
The findings are useful for devices working on double-diffusive natural convection inside non-homogenous cavities.
Originality/value
The authors believe that the presented results are original and have not been published elsewhere.
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Mohamed I.A. Othman, S.M. Abo-Dahab and Haneen A. Alosaimi
The purpose of this paper is to study a model of the equations of a two-dimensional problem in a half space, whose surface in a free micropolar thermoelastic medium possesses…
Abstract
Purpose
The purpose of this paper is to study a model of the equations of a two-dimensional problem in a half space, whose surface in a free micropolar thermoelastic medium possesses cubic symmetry as a result of inclined load. The problem is formulated in the context of Green-Naghdi theory of type II (G-N II) (without energy dissipation) and of type III (G-N III) (with energy dissipation) under the effect of magnetic field.
Design/methodology/approach
The normal mode analysis is used to obtain the exact expressions of the physical quantities.
Findings
The numerical results are given and presented graphically when the inclined load and magnetic field are applied. Comparisons are made with the results predicted by G-N theory of both types II and III in the presence and absence of the magnetic field and for different values of the angle of inclination.
Originality/value
In the present work, the authors study the influence of inclined load and magnetic field in a micropolar thermoelastic medium in the context of the G-N theory of both types II and III. Numerical results for the field quantities are obtained and represented graphically.
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Huey Tyng Cheong, S. Sivasankaran and M. Bhuvaneswari
The purpose of this paper is to study natural convective flow and heat transfer in a sinusoidally heated wavy porous cavity in the presence of internal heat generation or…
Abstract
Purpose
The purpose of this paper is to study natural convective flow and heat transfer in a sinusoidally heated wavy porous cavity in the presence of internal heat generation or absorption.
Design/methodology/approach
Sinusoidal heating is applied on the vertical left wall of the cavity, whereas the wavy right wall is cooled at a constant temperature. The top and bottom walls are taken to be adiabatic. The Darcy model is adopted for fluid flow through the porous medium in the cavity. The governing equations and boundary conditions are solved using the finite difference method over a range of amplitudes and number of undulations of the wavy wall, Darcy–Rayleigh numbers and internal heat generation/absorption parameters.
Findings
The results are presented in the form of streamlines, isotherms and Nusselt numbers for different values of right wall waviness, Darcy–Rayleigh number and internal heat generation parameter. The flow field and temperature distribution in the cavity are affected by the waviness of the right wall. The wavy nature of the cavity also enhances the heat transfer into the system. The heat transfer rate in the cavity decreases with an increase in the internal heat generation/absorption parameter.
Research limitations/implications
The present investigation is conducted for steady, two-dimensional natural convective flow in a wavy cavity filled with Darcy porous medium. The waviness of the right wall is described by the amplitude and number of undulations with a well-defined mathematical function. An extension of the present study with the effects of cavity inclination and aspect ratio will be the interest for future work.
Practical implications
The study might be useful for the design of solar collectors, room ventilation systems and electronic cooling systems.
Originality/value
This work examines the effects of sinusoidal heating on convective heat transfer in a wavy porous cavity in the presence of internal heat generation or absorption. The study might be useful for the design of solar collectors, room ventilation systems and electronic cooling systems.
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Mohamed I.A. Othman and Sudip Mondal
The purpose of this paper is to introduce the phase-lag models (Lord-Shulman, dual-phase-lag and three-phase-lag) to study the effect of memory-dependent derivative and the…
Abstract
Purpose
The purpose of this paper is to introduce the phase-lag models (Lord-Shulman, dual-phase-lag and three-phase-lag) to study the effect of memory-dependent derivative and the influence of thermal loading due to laser pulse on the wave propagation of generalized micropolar thermoelasticity. The bounding plane surface is heated by a non-Gaussian laser beam with a pulse duration of 10 nanoseconds.
Design/methodology/approach
The normal mode analysis technique is used to obtain the exact expressions for the displacement components, the force stresses, the temperature, the couple stresses and the micro-rotation. Comparisons are made with the results predicted by three theories of the authors’ interest. Excellent predictive capability is demonstrated at a different time also.
Findings
The effect of memory-dependent derivative and the heat laser pulse on the displacement, the temperature distribution, the components of stress, the couple stress and the microrotation vector have been depicted graphically.
Research limitations/implications
Some particular cases are also deduced from the present investigation.
Originality/value
The numerical results are presented graphically and are compared with different three theories for both in the presence and absence of memory-dependent effect and with the results predicted under three theories for two different values of the time.
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Mohamed I.A. Othman, W.M. Hasona and Elsayed M. Abd-Elaziz
The purpose of this paper is to introduce the coupled theory, Lord-Shulman theory with one relaxation time and Green-Lindsay theory with two relaxation times to study the…
Abstract
Purpose
The purpose of this paper is to introduce the coupled theory, Lord-Shulman theory with one relaxation time and Green-Lindsay theory with two relaxation times to study the influence of rotation on generalized micropolar thermoelasticity subject to thermal loading due to laser pulse. The bounding plane surface is heated by a non-Gaussian laser beam with pulse duration of 8 ps.
Design/methodology/approach
The problem has been solved numerically by using the normal mode analysis.
Findings
The thermal shock problem is studied to obtain the exact expressions for the displacement components, force stresses, temperature, couple stresses and micro-rotation. The distributions of the considered variables are illustrated graphically. Comparisons are made with the results predicted by three theories in the presence and absence of laser pulse and for different values of time.
Originality/value
Generalized micropolar thermoelastic solid.
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Keywords
Mohamed I.A. Othman and Mohamed F. Ismail
This paper aims to study the gravity effects on a micro-elongated thermoelastic layer under a fluid load, utilizing the Lord–Shulman (L-S) theory and the dual-phase-lag (DPL…
Abstract
Purpose
This paper aims to study the gravity effects on a micro-elongated thermoelastic layer under a fluid load, utilizing the Lord–Shulman (L-S) theory and the dual-phase-lag (DPL) model.
Design/methodology/approach
The analytical method used was the normal mode which partial differential equations transform into ordinary differential equations.
Findings
Aluminum epoxy numerical computations are carried out, and the results are graphed. The DPL model and the L-S theory are compared in the complete absence and presence of gravity. Comparisons were also made for three values of and it is observed that the gravity has quite a massive influence on all physical quantities.
Originality/value
In the present paper, the authors shall create the general equation for the energy equation, which includes the two theories (DPL and L-S) as well as the solution of micro-elongated thermoelasticity under fluid load. The problem is pretty important in many dynamical systems.