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Article
Publication date: 1 March 2003

Sorin Cioc and Theo G. Keith

A numerical scheme that has been successfully used to solve a wide variety of compressible flow problems, entitled the space‐time conservation element and solution element…

Abstract

A numerical scheme that has been successfully used to solve a wide variety of compressible flow problems, entitled the space‐time conservation element and solution element (CE/SE) method, is extended to predict the effects of gaseous cavitation in moderate to heavily loaded bearings. The formulation of the two‐dimensional, finite length, bearing problem is presented. The numerical results obtained are compared with other numerical solutions to demonstrate the superior ability of the method to solve such problems.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 13 no. 2
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 June 1992

KAMEL M. AL‐KHALIL, THEO G. JR. KEITH and KENNETH J. DE WITT

A numerical solution for ‘running wet’ aircraft anti‐icing systems is developed. The model includes breakup of the water film, which exists in regions of direct…

Abstract

A numerical solution for ‘running wet’ aircraft anti‐icing systems is developed. The model includes breakup of the water film, which exists in regions of direct impingement, into individual rivulets. The wetness factor distribution resulting from the film breakup and rivulet configuration on the surface are predicted in the numerical solution procedure. The solid wall is modelled as a multi‐layer structure and the anti‐icing system used is of the thermal type utilizing hot air and/or electrical heating elements embedded within the layers. Details of the calculation procedure and the methods used are presented.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 2 no. 6
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 January 1991

KAMEL M. AL‐KHALIL, THEO G. JR. KEITH and KENNETH J. DE WITT

The hydrodynamics and thermal characteristics of a laminar rivulet flow down a vertical surface are investigated. The velocity distribution within a rivulet is determined…

Abstract

The hydrodynamics and thermal characteristics of a laminar rivulet flow down a vertical surface are investigated. The velocity distribution within a rivulet is determined numerically by the use of a finite element method. In turn, a regression analysis is performed to fit the numerical data with an assumed closed form function. The breakup of a thin liquid film into rivulets is also considered. Heat transfer characteristics are determined. Nusselt numbers were obtained for the two cases of prescribed constant wall temperature and constant wall heat flux.

Details

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

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Article
Publication date: 1 June 2006

Sunil Mathew, Theo G. Keith Theo G. Keith Jr and Efstratios Nikolaidis

The purpose is to present a new approach for studying the phenomenon of traveling bubble cavitation.

Abstract

Purpose

The purpose is to present a new approach for studying the phenomenon of traveling bubble cavitation.

Design/methodology/approach

A flow around a rigid, 2D hydrofoil (NACA‐0012) with a smooth surface is analyzed computationally. The Rayleigh‐Plesset equation is numerically integrated to simulate the growth and collapse of a cavitation bubble moving in a varying pressure field. The analysis is performed for both incompressible and compressible fluid cases. Considering the initial bubble radius as a uniformly distributed random variable, the probability density function of the maximum collapse pressure is determined.

Findings

The significance of the liquid compressibility during bubble collapse is illustrated. Furthermore, it is shown that the initial size of the bubble has a significant effect on the maximum pressure generated during the bubble collapse. The maximum local pressure developed during cavitation bubble collapse is of the order of 104 atm.

Research limitations/implications

A single bubble model that does not account for the effect of neighboring bubbles is used in this analysis. A spherical bubble is assumed.

Originality/value

A new approach has been developed to simulate traveling bubble cavitation by interfacing a CFD solver for simulating a flow with a program simulating the growth and collapse of the bubble. Probabilistic analysis of the local pressure due to bubble collapse has been performed.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 16 no. 4
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 8 August 2008

Ramin K. Rahmani, Theo G. Keith and Anahita Ayasoufi

Fluid mixing plays a critical role in the success or failure of industrial processes which call for the addition of small quantities of chemicals to working fluid. This…

Abstract

Purpose

Fluid mixing plays a critical role in the success or failure of industrial processes which call for the addition of small quantities of chemicals to working fluid. This paper aims to describe how mixing processes of liquids in turbulent flow regime can be simulated numerically, present the flow pattern through a helical static mixer, and provide useful information that can be extracted from the simulation results.

Design/methodology/approach

The performance of a helical static mixer under turbulent flow conditions is numerically studied. The model solves the 3D Reynolds‐averaged Navier‐Stokes equations, closed with the Spalart‐Allmaras turbulence model, using a second‐order‐accurate finite‐volume numerical method. Numerical simulations are carried out for a six‐element mixer. Using a variety of predictive tools, mixing results are obtained and the performance of static mixer under turbulent flow condition is studied.

Findings

The upstream mixing elements increase the mixing more effectively compared to the downstream mixing elements; and also, the rate of mixing is higher in the regions close to the edges of mixing elements.

Practical implications

Static mixers have been widely used in the following industries: chemicals, food processing, heating, ventilation, and air conditioning, mineral processing, paints and resins, petrochemicals and refining, pharmaceuticals, polymers and plastics, pulp and paper, and water and waste treatment.

Originality/value

This paper fulfils an identified information need and offers practical help to an individual researcher in academia as well as industry.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 18 no. 6
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 December 1997

Chain‐Nan Yung, Kenneth J. De Witt, Srikanth Subramanian, Abdollah A. Afjeh and Theo G. Keith

Pulsatile flow of an incompressible, Newtonian fluid through a symmetric bifurcated rigid channel was numerically analysed by solving the three‐dimensional Navier‐Stokes…

Abstract

Pulsatile flow of an incompressible, Newtonian fluid through a symmetric bifurcated rigid channel was numerically analysed by solving the three‐dimensional Navier‐Stokes equations. The upstream flow conditions were taken from an experimentally measured human arterial pulse cycle. The bifurcation was symmetrical with a branch angle of 60° and a daughter to mother area ratio of 2.0. The predicted velocity patterns were in qualitative agreement with experimental measurements available in the literature. The effect of unsteadiness on the various flow characteristics was studied. The most drastic effect observed was on the flow reversal regions. There was no flow reversal at the highest inlet Reynolds number in the pulse cycle, whereas in the case of steady flow at the same Reynolds number, the flow reversal region was the largest. The presence of secondary flow was observed at all times during the pulse cycle. Shear stress was calculated along the outer and inner walls and the low and high time averaged shear stress regions correspond to the clinically observed sites of formation of atherosclerotic plaque and lesions.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 7 no. 8
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 February 2000

Yaw A. Debrah and Ian G. Smith

Presents over sixty abstracts summarising the 1999 Employment Research Unit annual conference held at the University of Cardiff. Explores the multiple impacts of…

Abstract

Presents over sixty abstracts summarising the 1999 Employment Research Unit annual conference held at the University of Cardiff. Explores the multiple impacts of globalization on work and employment in contemporary organizations. Covers the human resource management implications of organizational responses to globalization. Examines the theoretical, methodological, empirical and comparative issues pertaining to competitiveness and the management of human resources, the impact of organisational strategies and international production on the workplace, the organization of labour markets, human resource development, cultural change in organisations, trade union responses, and trans‐national corporations. Cites many case studies showing how globalization has brought a lot of opportunities together with much change both to the employee and the employer. Considers the threats to existing cultures, structures and systems.

Details

Management Research News, vol. 23 no. 2/3/4
Type: Research Article
ISSN: 0140-9174

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Article
Publication date: 13 July 2021

Włodzimierz Wróblewski, Krzysztof Bochon, Mirosław Majkut, Krzysztof Rusin and Emad Hasani Malekshah

The presence of air in the water flow over the hydrofoil is investigated. The examined hydrofoil is ClarkY 11.7% with an angle of attack of 8 deg. The flow simulations are…

Abstract

Purpose

The presence of air in the water flow over the hydrofoil is investigated. The examined hydrofoil is ClarkY 11.7% with an angle of attack of 8 deg. The flow simulations are performed with the assumption of different models. The Singhal cavitation model and the models which resolve the non-condensable gas including 2phases and 3phases are implemented in the numerical model. The calculations are performed with the uRANS model with assumption of the constant temperature of the mixture. The two-phase flow is simulated with a mixture model. The dynamics and structures of cavities are compared with literature data and experimental results.

Design/methodology/approach

The cavitation regime can be observed in some working conditions of turbomachines. The phase transition, which appears on the blades, is the source of high dynamic forces, noise and also can lead to the intensive erosion of the blade surfaces. The need to control this process and to prevent or reduce the undesirable effects can be fulfilled by the application of non-condensable gases to the liquid.

Findings

The results show that the Singhal cavitation model predicts the cavity structure and related characteristics differently with 2phases and 3phases models at low cavitation number where the cavitating flow is highly dynamic. On the other hand, the impact of dissolved air on the cloud structure and dynamic characteristic of cavitating flow is gently observable.

Originality/value

The originality of this paper is the evaluation of different numerical cavitation models for the prediction of dynamic characteristics of cavitating flow in the presence of air.

Details

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

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Article
Publication date: 1 April 2003

Georgios I. Zekos

Aim of the present monograph is the economic analysis of the role of MNEs regarding globalisation and digital economy and in parallel there is a reference and examination…

Abstract

Aim of the present monograph is the economic analysis of the role of MNEs regarding globalisation and digital economy and in parallel there is a reference and examination of some legal aspects concerning MNEs, cyberspace and e‐commerce as the means of expression of the digital economy. The whole effort of the author is focused on the examination of various aspects of MNEs and their impact upon globalisation and vice versa and how and if we are moving towards a global digital economy.

Details

Managerial Law, vol. 45 no. 1/2
Type: Research Article
ISSN: 0309-0558

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Article
Publication date: 1 May 1983

In the last four years, since Volume I of this Bibliography first appeared, there has been an explosion of literature in all the main functional areas of business. This…

Abstract

In the last four years, since Volume I of this Bibliography first appeared, there has been an explosion of literature in all the main functional areas of business. This wealth of material poses problems for the researcher in management studies — and, of course, for the librarian: uncovering what has been written in any one area is not an easy task. This volume aims to help the librarian and the researcher overcome some of the immediate problems of identification of material. It is an annotated bibliography of management, drawing on the wide variety of literature produced by MCB University Press. Over the last four years, MCB University Press has produced an extensive range of books and serial publications covering most of the established and many of the developing areas of management. This volume, in conjunction with Volume I, provides a guide to all the material published so far.

Details

Management Decision, vol. 21 no. 5
Type: Research Article
ISSN: 0025-1747

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