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Article
Publication date: 15 May 2009

Mohamed A. Antar and Maged A.I. El‐Shaarawi

The purpose of this paper is to investigate the problem of entropy generation around a spinning/non‐spinning solid sphere subjected to uniform heat flux boundary condition…

Abstract

Purpose

The purpose of this paper is to investigate the problem of entropy generation around a spinning/non‐spinning solid sphere subjected to uniform heat flux boundary condition in the forced‐convection regime.

Design/methodology/approach

The governing continuity, momentum, energy and entropy generation equations are numerically solved for a wide range of the controlling parameters; Reynolds number and the dimensionless spin number.

Findings

The dimensionless overall total entropy generation increases with the dimensionless spin number. The effect of increasing the spin number on the fluid‐friction component of entropy generation is more significant compared to its effect on heat transfer entropy generation.

Research limitations/implications

Since the boundary‐layer analysis is used, the flow is presented up to only the point of external flow separation.

Practical implications

Entropy generation analysis can be used to evaluate the design of many heat transfer systems and suggest design improvements.

Originality/value

A review in the open literature indicated that no study is available for the entropy generation in the unconfined flow case about a spinning sphere.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 19 no. 3/4
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 1 April 2014

M.A. Antar, Rached Ben-Mansour and Salem Ahmed Al-Dini

There are industrial applications for varying speed lid-driven flow and heat transfer such as the float glass process where the glass film stretches or thickens depending…

Abstract

Purpose

There are industrial applications for varying speed lid-driven flow and heat transfer such as the float glass process where the glass film stretches or thickens depending on the desired thickness. Hence the tin cavity underneath or the nitrogen cavity above is being driven by a variable speed. The purpose of this paper is to simulate such behavior.

Design/methodology/approach

Numerical solution of variable speed lid-driven cavity is carried out with thermal radiation being considered using control volume approach and staggered grid and applying the SIMPLE algorithm. Transient simulation is used for 2D model in the present study. Second order upwind schemes were used for discretization of momentum, energy equations and time.

Findings

Under laminar conditions, thermal radiation plays a significant role in the heat transfer characteristics of the lid-driven cavity. This effect is more significant for blackbody radiation and decreases as the surface emissivity decreases. Nusselt number (Nu) behavior lies between these two limiting case profiles considering constant speed profiles of both maximum and minimum lid velocities, respectively. In addition, local Nu values at the tip where higher than those at the top of the cavity that is stagnant.

Research limitations/implications

The study is limited to laminar flow case.

Practical implications

The applications of this study can be found in float glass process where the glass film stretches or thickens depending on the desired thickness. Hence the tin cavity underneath or the nitrogen cavity above is being driven by a variable speed. Another application involves casting of plastic films. The molten polymer leaves the die with a considerable thickness and high temperature. The film is then trenched to reach its final thickness. In this case, usually there is no actual cavity above or below the film but one can approximate the problem as such. Other similar applications do exist in food drying and processing where the conveyer belt is in portions and their speed may not be the same in different section of the processing oven.

Originality/value

To the best of the authors knowledge, no study in the literature addressed the effect of thermal radiation in lid-driven cavities with variable speed

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 24 no. 3
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 1 November 2002

M.A. Antar and M.A.I. El‐Shaarawi

Boundary‐layer flow around a spinning liquid sphere moving steadily in a gas stream is investigated numerically. The shear stress exerted on the sphere's surface results…

Abstract

Boundary‐layer flow around a spinning liquid sphere moving steadily in a gas stream is investigated numerically. The shear stress exerted on the sphere's surface results in surface rotation in the meridional direction in addition to the azimuthal velocity resulting from the spinning of the liquid sphere. The parameters controlling the flow around the sphere are the external flow Reynolds number (Re), the liquid‐to‐gas viscosity ratio (μ*) and the spinning parameter (Rer/Re)2. The effect of these parameters on the velocity components (namely the meridional, radial and azimuthal velocity components) and on the shear stress is shown. Moreover, their effect on the location of external flow point of separation is also demonstrated.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 12 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 25 February 2021

Leo Lukose and Tanmay Basak

The purpose of this paper is to address various works on mixed convection and proposes 10 unified models (Models 1–10) based on various thermal and kinematic conditions of…

Abstract

Purpose

The purpose of this paper is to address various works on mixed convection and proposes 10 unified models (Models 1–10) based on various thermal and kinematic conditions of the boundary walls, thermal conditions and/ or kinematics of objects embedded in the cavities and kinematics of external flow field through the ventilation ports. Experimental works on mixed convection have also been addressed.

Design/methodology/approach

This review is based on 10 unified models on mixed convection within cavities. Models 1–5 involve mixed convection based on the movement of single or double walls subjected to various temperature boundary conditions. Model 6 elucidates mixed convection due to the movement of single or double walls of cavities containing discrete heaters at the stationary wall(s). Model 7A focuses mixed convection based on the movement of wall(s) for cavities containing stationary solid obstacles (hot or cold or adiabatic) whereas Model 7B elucidates mixed convection based on the rotation of solid cylinders (hot or conductive or adiabatic) within the cavities enclosed by stationary or moving wall(s). Model 8 is based on mixed convection due to the flow of air through ventilation ports of cavities (with or without adiabatic baffles) subjected to hot and adiabatic walls. Models 9 and 10 elucidate mixed convection due to flow of air through ventilation ports of cavities involving discrete heaters and/or solid obstacles (conductive or hot) at various locations within cavities.

Findings

Mixed convection plays an important role for various processes based on convection pattern and heat transfer rate. An important dimensionless number, Richardson number (Ri) identifies various convection regimes (forced, mixed and natural convection). Generalized models also depict the role of “aiding” and “opposing” flow and combination of both on mixed convection processes. Aiding flow (interaction of buoyancy and inertial forces in the same direction) may result in the augmentation of the heat transfer rate whereas opposing flow (interaction of buoyancy and inertial forces in the opposite directions) may result in decrease of the heat transfer rate. Works involving fluid media, porous media and nanofluids (with magnetohydrodynamics) have been highlighted. Various numerical and experimental works on mixed convection have been elucidated. Flow and thermal maps associated with the heat transfer rate for a few representative cases of unified models [Models 1–10] have been elucidated involving specific dimensionless numbers.

Originality/value

This review paper will provide guidelines for optimal design/operation involving mixed convection processing applications.

Details

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

Keywords

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Article
Publication date: 6 June 2016

Ammar Mushtaq, M. Mustafa, T. Hayat and A. Alsaedi

– The purpose of this paper is to consider a laminar two-dimensional incompressible flow of an electrically conducting fluid over a moving flat plate with a parallel free stream.

Abstract

Purpose

The purpose of this paper is to consider a laminar two-dimensional incompressible flow of an electrically conducting fluid over a moving flat plate with a parallel free stream.

Design/methodology/approach

The governing equations are first reduced into self-similar forms and then solved for the numerical solutions by shooting method.

Findings

The results are compared with the available studies is some special cases and found in excellent agreement. It is noticed that an increase in the magnetic field strength leads to a decrease in the momentum boundary layer thickness and enhancement in the rate of heat transfer from the plate. It is also observed that temperature and heat transfer from the plate increase when radiation effect is strengthened.

Originality/value

A recently proposed idea of nonlinear radiative heat transfer with Joule heating and viscous dissipation effects is analyzed.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 26 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 8 May 2018

Sen-Yung Lee, Li-Kuo Chou and Chao Kuang Chen

The purpose of this paper is to propose the Laplace Adomian Decomposition Method (LADM) for studying the nonlinear temperature and thermal stress analysis of annular fins…

Abstract

Purpose

The purpose of this paper is to propose the Laplace Adomian Decomposition Method (LADM) for studying the nonlinear temperature and thermal stress analysis of annular fins with time-dependent boundary condition.

Design/methodology/approach

The nonlinear behavior of temperature and thermal stress distribution in an annular fin with rectangular profile subjected to time-dependent periodic temperature variations at the root is studied by the LADM. The radiation effect is considered. The convective heat transfer coefficient is considered as a temperature function.

Findings

The proposed solution method is helpful in overcoming the computational bottleneck commonly encountered in industry and in academia. The results show that the circumferential stress at the root of the fin will be important in the fatigue analysis.

Originality/value

This study presents an effective solution method to analyze the nonlinear behavior of temperature and thermal stress distribution in an annular fin with rectangular profile subjected to time-dependent periodic temperature variations at the root by using LADM.

Details

Engineering Computations, vol. 35 no. 3
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 4 September 2019

Sa'd Shannak and Malak Alnory

Solar as an energy source has a massive potential to reduce dependence on fossil fuels in Gulf Countries (GC). One attractive application of solar energy is solar-powered…

Abstract

Purpose

Solar as an energy source has a massive potential to reduce dependence on fossil fuels in Gulf Countries (GC). One attractive application of solar energy is solar-powered desalination, which is a viable method to produce fresh water. The most significant factor determining the potential deployment of this application is economics.

Design/methodology/approach

In this study, the classical economic analysis model has been modified to assess the penetration of solar technology to power desalination plants at different periods during the project lifetime. Furthermore, the environmental and financial values were combined to assess the incentive of powering desalination plants with solar energy in Saudi Arabia. Three systems of solar technologies accompanied with water desalination based on technical applicability were modeled and economically analyzed to understand the impact of various design and operation parameters.

Findings

This study shows that PV-RO is currently more competitive at both market and administrated prices in Saudi Arabia, followed by the MED-CSP system and finally CSP-RO system. CSP-RO system starts to generate positive surplus after 11 years, while the base case shows no positive surplus at all during the entire lifetime. Moreover, the same trend continues to hold with MED-CSP and PV-RO systems. The MED-CSP generates positive surplus after six years and PV-RO after five years only. On average, it takes eight years for a project running based on solar (CAPEX and OPEX) and desalination OPEX to generate positive cash surplus.

Originality/value

This paper discusses the debate about incentives for renewable energy in GC and the impact of coupling water production and solar generation. Given that there is no analytical framework built earlier, this paper provides an alternative methodology for policy analysis to understand the role of economies of scope to incentivize solar generation. In other words, the authors are investigating options to reduce the total cost of solar production as a result of increasing the number of different goods produced.

Details

Journal of Science and Technology Policy Management, vol. 11 no. 3
Type: Research Article
ISSN: 2053-4620

Keywords

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Article
Publication date: 25 November 2020

Lilly-Mari Sten, Pernilla Ingelsson, Ingela Bäckström and Marie Häggström

The purpose of this literature review was to explore to what extent quality management (QM) and nursing science offer complementary perspectives to provide better quality…

Abstract

Purpose

The purpose of this literature review was to explore to what extent quality management (QM) and nursing science offer complementary perspectives to provide better quality care, by looking at QM core concepts and tools.

Design/methodology/approach

A systematic literature review was conducted. Papers published in academic journals between January 2013 and December 2019 were included. A deductive content analysis was chosen using QM core values as an analytical framework.

Findings

The results showed that QM core values, methodologies and tools were found in the reviewed articles about intensive care unit (ICU) transitional care. The results indicated that core values in QM and the core competencies within nursing science in ICU transitional care are mutually dependent upon each other and exist as a whole. ICU transitional care is, however, a complex interpersonal process, characterized by differences in organizational cultures and core values and involving multidisciplinary teams that collaborate across hospital units. The QM core value that was least observed was committed leadership.

Research limitations/implications

Combining QM and nursing science can contribute to a deeper understanding of how to improve the ICU transitional care process by bringing complementary perspectives.

Practical implications

The included articles portray how QM is applied in ICU transitional care. Implications for future research focus on enhancing the understanding of how QM and nursing science can bring complementary perspectives in order to improve ICU transitional care and how QM values, methodologies and tools can be used in ICU transitional care. Committed leadership and team collaboration in ICU transitional care are areas that call for further research.

Originality/value

The findings contribute to the body of literature by providing important insights in terms of how QM core values, methodologies and tools are present in research about ICU transitional care and how the two research subjects, namely, QM and nursing science, bring complementary perspectives.

Details

International Journal of Quality and Service Sciences, vol. 12 no. 3
Type: Research Article
ISSN: 1756-669X

Keywords

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Case study
Publication date: 20 January 2017

Elizabeth A. Powell and Antar Al-Qawwee

Antar Al-Qawwee describes in vivid detail his first days on the job at his summer internship in Sales and Trading and reflects on the lessons he learned through careful…

Abstract

Antar Al-Qawwee describes in vivid detail his first days on the job at his summer internship in Sales and Trading and reflects on the lessons he learned through careful observation. Among the lessons he identifies are (1) Speak up early and often; (2) Be flexible and adjust your style; (3) Fate favors the prepared; and (4) Be yourself. As important as these explicit lessons are, equally important are the skills of presence of mind, mindful self-awareness, and sensitive reading of people and situations that he demonstrates.

Details

Darden Business Publishing Cases, vol. no.
Type: Case Study
ISSN: 2474-7890
Published by: University of Virginia Darden School Foundation

Keywords

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Article
Publication date: 25 November 2019

Antar Si Mohammed, Rachid Smail and Mourad Chebila

The purpose of this paper is to develop an advanced decision-making support for the appropriate responding to critical alarms in the hazardous industrial facilities.

Abstract

Purpose

The purpose of this paper is to develop an advanced decision-making support for the appropriate responding to critical alarms in the hazardous industrial facilities.

Design/methodology/approach

A fuzzy analytical hierarchy process is suggested by considering three alternatives and four criteria using triangular fuzzy numbers to handle the associated uncertainty. A logarithmic fuzzy preference programming (LFPP)-based nonlinear priority method is employed to analyze the suggested model.

Findings

A quantitative decision-making support is not only a necessity in responding to critical alarms but also easy to implement even in a relatively short reaction time. Confirmation may not be the appropriate option to deal with a critical alarm, even with the availability of the needed resources.

Practical implications

A situation related to a flammable gas alarm in a gas plant is treated using the developed model showing its practical efficiency and practicality.

Originality/value

The proposed model provides a rational, simple and holistic fuzzy multi criteria tool with a refined number of criteria and alternatives using an LFPP method to handle process alarms.

Details

International Journal of Quality & Reliability Management, vol. 37 no. 8
Type: Research Article
ISSN: 0265-671X

Keywords

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