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Article
Publication date: 12 June 2017

Syed Tauseef Mohyud-din, Umar Khan, Naveed Ahmed and M.M. Rashidi

The purpose of this paper is to present investigation of the flow, heat and mass transfer of a nanofluid over a suddenly moved flat plate using Buongiorno’s model. This…

Abstract

Purpose

The purpose of this paper is to present investigation of the flow, heat and mass transfer of a nanofluid over a suddenly moved flat plate using Buongiorno’s model. This study is different from some of the previous studies as the effects of Brownian motion and thermophoresis on nanoparticle fraction are passively controlled on the boundary rather than actively.

Design/methodology/approach

The partial differential equations governing the flow are reduced to a system of non-linear ordinary differential equations. Viable similarity transforms are used for this purpose. A well-known numerical scheme called Runge-Kutta-Fehlberg method coupled with shooting procedure has been used to find the solution of resulting system of equations. Discussions on the effects of different emerging parameters are provided using graphical aid. A table is also given that provides the results of different parameters on local Nusselt and Sherwood numbers.

Findings

A revised model for Stokes’ first problem in nanofluids is presented in this paper. This model considers a zero flux condition at the boundary. Governing equations after implementing the similarity transforms get converted into a system of non-linear ordinary differential equations. Numerical solution using RK-Fehlberg method is also carried out. Emerging parameters are analyzed graphically. Figures indicate a quite significant change in concentration profile due to zero flux condition at the wall.

Originality/value

This work can be extended for other problems involving nanofluids for the better understanding of different properties of nanofluids.

Details

Multidiscipline Modeling in Materials and Structures, vol. 13 no. 1
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 18 April 2017

Syed Tauseef Mohyud-din, Naveed Ahmed, Umar Khan and Mohammad Mehdi Rashidi

The purpose of this study is to analyze thermo-diffusion and diffusion-thermo effects, combined with first-order chemical reaction, in the flow of a micropolar fluid…

Abstract

Purpose

The purpose of this study is to analyze thermo-diffusion and diffusion-thermo effects, combined with first-order chemical reaction, in the flow of a micropolar fluid through an asymmetric channel with porous boundaries. Suction/injection velocities of upper and lower walls are taken to be different from each other. The channel exhibits a parting or embracing motion and the fluid enters, or leaves, the channel because of suction/injection through the permeable walls.

Design/methodology/approach

The solution of the problem is obtained by using the fourth-order Runge-Kutta method combined with the shooting technique.

Findings

The asymmetric nature of the channel that is caused by the different permeabilities of the walls deeply influences the flow. The temperature of the fluid rises significantly by increasing the absolute value of A for both Case I and Case II. While, for the concentration profile, the concentration drops near the lower vicinity of the center in Case I, and, it falls near the lower wall of the channel in Case II. Stronger Dufour effects increase the temperature of the fluid except for Case 1 at the center of the channel and for Case II in lower quarter of the channel.

Originality/value

It is confirmed that the presented work is original and is not under consideration by any other journal.

Details

Engineering Computations, vol. 34 no. 2
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 6 November 2017

Naveed Ahmed, Umar Khan, Syed Tauseef Mohyud-Din and Saeed Ullah Jan

In this current study, the authors aim to analyze non-linear radiative squeezed flow in a rotating frame of viscous fluid.

Abstract

Purpose

In this current study, the authors aim to analyze non-linear radiative squeezed flow in a rotating frame of viscous fluid.

Design/methodology/approach

The Radioactive nature of the fluid is taken into consideration. The reduced form of equations governing the flow are developed by the implementation of similarity transformations. The coupled system thus obtained is solved by using the homotopy analysis method (HAM).

Findings

Augmentation in velocity and temperature profiles is discussed graphically by varying various involved parameters. The total error of the system is discussed in Table I. The cases of linear radiation and non-linear radiation are also discussed in Tables II and III.

Originality/value

The study presented in this paper is original and it has not been submitted to any other journal for publication purpose. The contents are original and proper references have been provided wherever applicable.

Details

Engineering Computations, vol. 34 no. 8
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 2 May 2017

Naveed Ahmed, Umar Khan and Syed Tauseef Mohyud-din

The aim of this manuscript is to study the flow of a nanofluid through a porous channel under the influence of a transverse magnetic field. Permeability of the walls is…

Abstract

Purpose

The aim of this manuscript is to study the flow of a nanofluid through a porous channel under the influence of a transverse magnetic field. Permeability of the walls is considered to be different, which results in an asymmetric nature of the flow. The height of the channel is variable, and it dilates or squeezes at a uniform rate.

Design/methodology/approach

A numerical solution (Runge–Kutta–Fehlberg) has been obtained after reducing the governing equations to a system of nonlinear ordinary differential equations using some suitable similarity transforms, both in time and space.

Findings

An increase in absolute values of the permeability parameter results in an enhanced mass transfer rate at both the walls, while the rate of heat transfer also increases at the lower wall. Few graphs are also dedicated to see the behavior of Nusselt and Sherwood numbers following the variations in flow parameters.

Originality/value

A pictorial description of the flow and effects of emerging parameters on the temperature and nanoparticle concentration profiles is presented to analyze the flow behavior. It is established that the asymmetry of the channel affects the flow quite significantly.

Details

Engineering Computations, vol. 34 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 4 September 2017

Syed Tauseef Mohyud-Din, Naveed Ahmed and Umar Khan

The purpose of this study is to investigate numerically the influence of nonlinear thermal radiation on the flow of a viscous fluid. The flow is confined in a channel with…

Abstract

Purpose

The purpose of this study is to investigate numerically the influence of nonlinear thermal radiation on the flow of a viscous fluid. The flow is confined in a channel with deformable porous walls.

Design/methodology/approach

Two numerical schemes, namely, Galerkin’s method (GM) and Runge–Kutta–Fehlberg (RKF) method have been used to obtain solutions after reducing the governing equations to a system of nonlinear ordinary differential equations.

Findings

Heat transfer rate falls at the upper wall owing to the decreasing values of the permeability parameter. However, at the lower wall, the same rate rises. Increment in θw increases the rate of heat transfer at both walls. Nusselt number also increases with the increasing values of Rd. Rd also uplifts the temperature distribution, except for the case where it falls near the lower wall owing to the contraction coupled with injection.

Originality/value

It is confirmed that the presented work is original.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 9
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 6 November 2017

Umar Khan, Adnan Abbasi, Naveed Ahmed and Syed Tauseef Mohyud-Din

This paper aims to explore the flow of nanofluid over bi-directional stretching sheet in the presence of magnetic field and linear thermal radiation.

Abstract

Purpose

This paper aims to explore the flow of nanofluid over bi-directional stretching sheet in the presence of magnetic field and linear thermal radiation.

Design/methodology/approach

In this study, water is taken as a base fluid, and copper is diluted in the base fluid. Further, four different shapes of nanoparticles are considered for the analysis. The governing nonlinear partial differential equations are transformed into the system of ordinary differential equations after using the feasible similarity transformations. Solution of the model is then performed by means of Runge–Kutta scheme.

Findings

Influence of the emerging dimensionless parameters on velocity, temperature, skin friction coefficient and local rate of heat transfer are studied with the help of graphs.

Originality/value

The study is presented in this paper is original and has not been submitted to any other journal for the publication purpose. The contents are original, and proper references have been provided wherever applicable.

Details

Engineering Computations, vol. 34 no. 8
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 7 June 2019

Naveed Ahmed and Talat Afza

The purpose of this paper is to explore the moderating role of competitive intensity between the existing relationship of capital structure and firm performance.

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Abstract

Purpose

The purpose of this paper is to explore the moderating role of competitive intensity between the existing relationship of capital structure and firm performance.

Design/methodology/approach

Using the balanced panel data of listed non-financial firms of Pakistan, the present study adopts both the panel and OLS estimation techniques to draw the inferences.

Findings

The results exhibit that high debt ratio is harmful for the accounting performance of the selected sample firms of Pakistan. In addition, product market competition negatively moderates the relationship between capital structure and firm performance which suggests that high product market competition can be used as a substitute of debt financing to align the interests of a firm’s managers and shareholders.

Practical implications

The findings of the research provide evidence for the policy makers/regulators that the sample firms should discourage the high debt financing in the presence of competitive intensity in the product marketplace.

Originality/value

The core contribution of the current research is to examine the moderating role of product market competition on the leverage–performance relationship because, to the best of the authors’ knowledge, no single study has previously explored this relationship in the context of Pakistan.

Details

Journal of Advances in Management Research, vol. 16 no. 5
Type: Research Article
ISSN: 0972-7981

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Article
Publication date: 3 January 2017

Umar Khan, Naveed Ahmed, Bandar Bin-Mohsen and Syed Tauseef Mohyud-Din

The purpose of this paper is to assess the flow of a nanofluid over a porous moving wedge. The passive control model along with the magnetohydrodynamic (MHD) effects is…

Abstract

Purpose

The purpose of this paper is to assess the flow of a nanofluid over a porous moving wedge. The passive control model along with the magnetohydrodynamic (MHD) effects is used to formulate the problem. Furthermore, in energy equation, the non-linear thermal radiation has also been incorporated. The equations governing the flow are transformed into a set of ordinary differential equations by using suitable similarity transforms. The reduced system of equations is then solved numerically using a well-known Runge–Kutta–Fehlberg method coupled with a shooting technique. The influence of parameters involved on velocity, temperature and concentration profiles is highlighted with the help of a graphical aid. Expressions for skin-friction coefficient, local Nusselt number and Sherwood number are obtained and presented graphically.

Design/methodology/approach

Numerical solution of the problem is obtained using the well-known Runge–Kutta–Fehlberg method.

Findings

The analysis provided gives a clear description that the increase in m and magnetic parameter M results in an increased velocity profile. Both these parameters normalize the velocity field. Radiation parameter, Rd, increases the temperature and concentration of the system so does the temperature ratio θω reduces the heat transfer rate at the wall for both stretching and shrinking wedge.

Originality/value

In the study presented, the flow of nanofluid over a moving permeable wedge is considered. The solution of the equations governing the flow is presented numerically. For the validity of results obtained, a comparison is also presented with already existing results. To the best of the authors’ knowledge, this investigation is the first of its kind on the said topic.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 6 November 2017

Umar Khan, Adnan Abbasi, Naveed Ahmed and Syed Tauseef Mohyud-Din

The purpose of this paper is to explore the impact of thermal radiation, viscous dissipation and Joule heating effects on the flow of a magneto-nanofluid between two…

Abstract

Purpose

The purpose of this paper is to explore the impact of thermal radiation, viscous dissipation and Joule heating effects on the flow of a magneto-nanofluid between two horizontally placed plates. Three distinct shapes of nanoparticles in a base fluid (water) are considered to compose the nanofluid.

Design/methodology/approach

Introducing feasible similarity variables, the flow model is transformed into a nonlinear and coupled system of ordinary differential equations. The consequent system is solved by using homotopy analysis method.

Findings

Furthermore, the influence of embedded parameters on velocity and temperature profiles is highlighted graphically. The same is done for showing the variations in skin friction coefficient and local rate of heat transfer. Under certain conditions, present results compared with already existing results in the literature. Some main findings are pinpointed in the last section before the bibliography. From presented work, it is analyzed that the velocity field along y-axis and x-axis are increasing and decreasing functions of suction/injection parameter. The velocity of the fluid starts increases for Reynolds number and declines for volumetric fraction of the nanoparticles. Significant variations in angular velocity are observed for volumetric fraction and Reynolds number, respectively. Thermal field increases rapidly for brick-shaped nanoparticles, and for platelet-shaped nanoparticles, it decreases rapidly. Local rate of heat transfer increases for radiation and Reynolds number and starts decreasing for Eckert number.

Originality/value

The study presented is original and has not been submitted to any other journal for the publication purpose. The contents are original and proper references have been provided wherever applicable.

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Article
Publication date: 31 December 2019

Mona Jami Pour, Javad Mesrabadi and Mahnaz Hosseinzadeh

Today, the high cost of e-learning systems’ implementation and the difficulty of managing the infrastructures motivate educational institutions toward application of…

Abstract

Purpose

Today, the high cost of e-learning systems’ implementation and the difficulty of managing the infrastructures motivate educational institutions toward application of cloud-based e-learning systems. This new system should be aligned with the academics’ aims and pedagogical principles to be beneficial for learners and instructors. Therefore, the vendor selection of learning systems is one of the most important processes to migrate toward cloud-based e-learning. The purpose of this paper is to develop a new framework to facilitate the vendor selection of cloud-based e-learning systems in the cloud market.

Design/methodology/approach

To identify the initial criteria as to the vendor selection of cloud-based e-learning services, a literature review is done. To enrich the initial criteria, a focus group of experts is investigated, and the framework developed; then, a survey analysis is conducted to validate the proposed framework. The extracted criteria and sub-criteria are weighted and prioritized using best-worst method (BWM).

Findings

The results indicate that the main dimensions of vendor selection framework as regards cloud-based e-learning systems are managerial, technological and pedagogical factors. The rank orders and weights of the mentioned aspects and their sub-criteria are calculated using the BWM.

Practical implications

The proposed framework helps managers to get a big picture of requirements as to cloud-based e-learning and more effectively to select appropriate vendors in this initiative. In the vendor selection process, managers must pay attention to technological issues as well as managerial and pedagogical considerations.

Originality/value

Cloud-based e-learning systems are getting increasingly essential to offer training courses more efficiently in educational institutions. Although the intersection between cloud computing and e-learning has increasingly grown in both practical and academic contexts, there are little studies on how educational institutions and organizations could be able to select appropriate cloud-based e-learning systems. This paper explores the ignored but critically important subject of cloud-based e-learning. The main contribution of this paper is to propose a novel and integrated framework containing the important aspects of vendor selection in cloud-based e-learning services. The proposed framework comprises managerial, technological and pedagogical aspects simultaneously as well as sub-criteria denoting each aspect.

Details

Online Information Review, vol. 44 no. 1
Type: Research Article
ISSN: 1468-4527

Keywords

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