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Article
Publication date: 15 May 2009

H. Parhizkar and S.M.H. Karimian

The purpose of this paper is to present an engineering inviscid‐boundary layer method for the calculation of convective heating rates on three‐dimensional non‐axisymmetric…

409

Abstract

Purpose

The purpose of this paper is to present an engineering inviscid‐boundary layer method for the calculation of convective heating rates on three‐dimensional non‐axisymmetric geometries at angle of attack.

Design/methodology/approach

Based on the axisymmetric analog, convective heating rates are calculated along the surface streamlines which are determined using the inviscid properties calculated on an unstructured grid.

Findings

Since the method is capable of using inviscid properties calculated on an unstructured grid, it is applicable to a variety of configurations and it requires much less computational effort than a Navier‐Stokes code. The results of the present method are evaluated on different wing body configurations in laminar and turbulent hypersonic equilibrium flows. In comparison to experimental data, the present results are found to be fairly accurate in the windward and leeward regions.

Practical implications

With this approach, heating rates can be predicted on general three‐dimensional configurations at hypersonic speeds in an accurate and fast scheme.

Originality/value

In order to calculate the heating rates at any specific point on the surface, a technique is developed to calculate the inviscid surface streamlines in a backward manner using the inviscid velocity components. The metric coefficients are also calculated using a new simple technique.

Details

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

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Article
Publication date: 11 January 2008

S. Noori, S.M.H. Karimian and M. Malekzadeh Dirin

This paper aims to predict aerodynamic heating through the efficient solution of three‐dimensional viscous shock layer (VSL) equations, using axisymmetric analog.

248

Abstract

Purpose

This paper aims to predict aerodynamic heating through the efficient solution of three‐dimensional viscous shock layer (VSL) equations, using axisymmetric analog.

Design/methodology/approach

The three‐dimensional VSL equations are written in the curvilinear streamline coordinate system. In these equations, normal momentum equation is replaced by Maslen's pressure relation. In addition to this, axisymmetric analog is implemented along the streamlines through assuming a zero value for circumferential velocity component. In this case, three‐dimensional VSL equations are reduced into an axisymmetric form, which can be solved much easier.

Findings

It is demonstrated that the solution of three‐dimensional VSL equations in the curvilinear streamline coordinate system, using axisymmetric analog, has made it possible to predict convective heat fluxes in both windward and leeward regions. Moreover, in comparison with the 3D VSL methods, the present approach dramatically reduces the CPU time of calculations. Comparison with the experimental and numerical data shows a good agreement between both of these data and the present results.

Practical implications

This method is an excellent tool for parametric study and preliminary design of hypersonic vehicles.

Originality/value

This method can predict convective heat flux in the leeward region where other similar methods are not applicable. In addition to this the present method is faster than other methods of solution for the 3D VSL equations.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 18 no. 1
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 25 July 2019

Seyedmohammad Mousavisani, Javad Khalesi, Hossein Golbaharan, Mohammad Sepehr and D.D. Ganji

The purpose of this paper is to find the approximate solutions of unsteady squeezing nanofluid flow and heat transfer between two parallel plates in the presence of variable heat…

113

Abstract

Purpose

The purpose of this paper is to find the approximate solutions of unsteady squeezing nanofluid flow and heat transfer between two parallel plates in the presence of variable heat source, viscous dissipation and inclined magnetic field using collocation method (CM).

Design/methodology/approach

The partial governing equations are reduced to nonlinear ordinary differential equations by using appropriate transformations and then are solved analytically by using the CM.

Findings

It is observed that the enhancing values of aligned angle of the magnetic causes a reduction in temperature distribution. It is also seen that the effect of nanoparticle volume fraction is significant on the temperature but negligible on the velocity profile.

Originality/value

To the best of the authors’ knowledge, no research has been carried out considering the combined effects of inclined Lorentz forces and variable heat source on squeezing flow and heat transfer of nanofluid between the infinite parallel plates.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 6 July 2010

Hamed Sadeghi, Mahmoud Mani and S.M. Hossein Karimian

The primary purpose of this paper is to investigate the characteristics of the unsteady flow field in the wake of Eppler‐361 airfoil undergoing harmonic pitch oscillation in both…

1165

Abstract

Purpose

The primary purpose of this paper is to investigate the characteristics of the unsteady flow field in the wake of Eppler‐361 airfoil undergoing harmonic pitch oscillation in both pre‐stall and post‐stall regimes.

Design/methodology/approach

Experimental measurements were carried out to study the characteristics of the unsteady flow field within the wake of an airfoil. All of the experiments were conducted in a low‐speed wind tunnel, and the velocity field was measured by a hot‐wire anemometry. The airfoil was given a harmonic pitching motion about its half chord axis at two reduced frequencies of 0.091 and 0.273. All experimental data were taken at the oscillation amplitude of 8°. During the experiments, the mean angle of attack was altered from 2.5 to 10° that this made it possible to study the wake in both pre‐stall and post‐stall regimes.

Findings

From the results, it can be concluded that different velocity profiles are formed in the wake at different phase angles. In addition, the hysteresis of the velocity field in the wake is captured between increasing and decreasing incidences. It is also found that the velocity field in the wake is strongly affected by the operating conditions of the airfoil, e.g. mean angle of attack, reduced frequency and instantaneous angle of attack. Huge variations in the profiles of the wake are observed at high instantaneous angles of attack when the mean angle of attack is 10°, i.e. when the airfoil experiences significant oscillations beyond the static stall. It is concluded that this is due to dynamic stall phenomenon.

Practical implications

Findings of the present study give valuable information, which can be used to characterize wakes of micro air vehicles, helicopter's rotor blades, and wind turbine blades. In addition to this, present findings can be used to predict dynamic stall of the above applications.

Originality/value

The paper is the first to investigate the unsteady wake of Eppler‐361 airfoil and to predict the dynamic stall phenomenon of this airfoil.

Details

Aircraft Engineering and Aerospace Technology, vol. 82 no. 4
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 October 2004

M.F. Webster, I.J. Keshtiban and F. Belblidia

We introduce a second‐order accurate time‐marching pressure‐correction algorithm to accommodate weakly‐compressible highly‐viscous liquid flows at low Mach number. As the…

800

Abstract

We introduce a second‐order accurate time‐marching pressure‐correction algorithm to accommodate weakly‐compressible highly‐viscous liquid flows at low Mach number. As the incompressible limit is approached (Ma ≈ 0), the consistency of the compressible scheme is highlighted in recovering equivalent incompressible solutions. In the viscous‐dominated regime of low Reynolds number (zone of interest), the algorithm treats the viscous part of the equations in a semi‐implicit form. Two discrete representations are proposed to interpolate density: a piecewise‐constant form with gradient recovery and a linear interpolation form, akin to that on pressure. Numerical performance is considered on a number of classical benchmark problems for highly viscous liquid flows to highlight consistency, accuracy and stability properties. Validation bears out the high quality of performance of both compressible flow implementations, at low to vanishing Mach number. Neither linear nor constant density interpolations schemes degrade the second‐order accuracy of the original incompressible fractional‐staged pressure‐correction scheme. The piecewise‐constant interpolation scheme is advocated as a viable method of choice, with its advantages of order retention, yet efficiency in implementation.

Details

Engineering Computations, vol. 21 no. 7
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 1 October 2005

B.J. Henz, K.K. Tamma, R.V. Mohan and N.D. Ngo

The purpose of the present paper is to describe the modeling, analysis and simulations for the resin transfer molding (RTM), manufacturing process with particular emphasis on the…

947

Abstract

Purpose

The purpose of the present paper is to describe the modeling, analysis and simulations for the resin transfer molding (RTM), manufacturing process with particular emphasis on the sensitivity analysis for non‐isothermal applications.

Design/methodology/approach

For the manufacturing of advanced composites via RTM, besides the tracking of the resin flow fronts through a porous fiber perform, the heat transfer and the resin cure kinetics play an important role. The computational modeling is coupled multi‐disciplinary problem of flow‐thermal‐cure. The paper describes the so‐called continuous sensitivity formulation via the finite element method for this multi‐disciplinary problem for process modeling of composites manufactured by RTM to predict, analyze and optimize the manufacturing process.

Findings

Illustrative numerical examples are presented for two sample problems which include examination of sensitivity parameters for the case of material and geometric properties, and boundary conditions including fill time sensitivity analysis. The results indicate that the proposed formulations serve a useful role for the design and optimization of the RTM manufacturing process, thereby, avoiding heuristic trial‐and‐error methods.

Research limitations/implications

The paper restricts attention to constant properties and extensions to non‐linear thermophysical properties will serve as an added benefit.

Practical implications

The present efforts significantly impact the design/optimization process in the process modeling of composites manufactured by RTM.

Originality/value

To the authors' knowledge, this is the first time that continuous sensitivity analysis is done for non‐isothermal considerations in RTM.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 15 no. 7
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 28 February 2019

Saeed Haji Karimian, Jasper Mbachu, Temitope Egbelakin and Wajiha Shahzad

The purpose of this paper is to investigate the key productivity constraints faced by New Zealand (NZ) road pavement maintenance and rehabilitation contractors (RPMRCs) and the…

712

Abstract

Purpose

The purpose of this paper is to investigate the key productivity constraints faced by New Zealand (NZ) road pavement maintenance and rehabilitation contractors (RPMRCs) and the associated mitigation measures.

Design/methodology/approach

Interview-based exploratory research strategy was used to survey senior managers and directors of medium- to large-sized road contracting firms in NZ. Empirical data were analyzed using the multi-attribute analytical technique.

Findings

Results revealed 70 productivity constraints faced by the RPMRCs in NZ; in diminishing order of influence, these constraints were aggregated into eight broad categories as follows: finance, workforce, technology/process, statutory/regulatory compliance, project characteristics, project management/project team characteristics, unforeseen circumstances and other/external factors. The most important constraints in each of the eight broad categories were presented.

Research limitations/implications

The key limitation of the research is that it was based on feedback from a limited number of participants which were less than the minimum required to represent the views of the potential participants in the sampling frame for the study. As a result, the findings may not be reliably generalized beyond the scope of the data used. Further research on the subject is recommended to ensure that the representation of the views of the individuals and companies that comprised the sampling frame is achieved. The current findings could be formulated as propositions or hypotheses to be tested in future confirmatory research.

Practical implications

At the industry level, the findings could provide the basis for the skill development programs of the NZ RPMRCs. The application of the research findings by the RPMRCs and consultants could result in significant improvement in the productivity of the NZ roading sector and the sector’s enhanced contribution to the economy.

Originality/value

Currently, there is little research on the priority constraints to productivity and performance in the NZ roading sector. The findings contribute to knowledge by revealing critical factors constraining productivity performance of the NZ RMRCs and the associated improvement measures. New and more enriching viewpoints were provided on how contractors could leverage their limited resources to address the identified key constraints.

Details

Engineering, Construction and Architectural Management, vol. 26 no. 5
Type: Research Article
ISSN: 0969-9988

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Book part
Publication date: 30 January 2025

Seyi S. Stephen, Ayodeji E. Oke, Clinton O. Aigbavboa, Opeoluwa I. Akinradewo, Pelumi E. Adetoro and Matthew Ikuabe

The chapter explored integrating smart construction techniques in achieving stealth construction objectives, emphasising the development of building cross-sections, visibility…

Abstract

The chapter explored integrating smart construction techniques in achieving stealth construction objectives, emphasising the development of building cross-sections, visibility management, energy transmission optimisation, and countermeasure implementation. It delved into the multifaceted aspects of smart construction towards achieving stealth construction goals, including environmental protection, enhanced construction safety, accelerated construction duration, cost-effectiveness, and aesthetic considerations. Furthermore, the chapter underscores the importance of leveraging innovative approaches and advanced technologies to meet the evolving demands of stealth construction projects and pave the way for sustainable, safe, and aesthetically pleasing built environments.

Details

Stealth Construction: Integrating Practices for Resilience and Sustainability
Type: Book
ISBN: 978-1-83608-183-8

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Article
Publication date: 24 October 2024

James Elgy and Paul David Ledger

Magnetic polarizability tensors (MPTs) provide an economical characterisation of conducting magnetic metallic objects and their spectral signature can aid in the solution of metal…

11

Abstract

Purpose

Magnetic polarizability tensors (MPTs) provide an economical characterisation of conducting magnetic metallic objects and their spectral signature can aid in the solution of metal detection inverse problems, such as scrap metal sorting, searching for unexploded ordnance in areas of former conflict and security screening at event venues and transport hubs. In this work, the authors aim to discuss methods for efficiently building large dictionaries for classification approaches.

Design/methodology/approach

Previous work has established explicit formulae for MPT coefficients, underpinned by a rigorous mathematical theory. To assist with the efficient computation of MPTs at differing parameters and objects of interest, this work applies new observations about the way the MPT coefficients can be computed. Furthermore, the authors discuss discretisation strategies for hp-finite elements on meshes of unstructured tetrahedra combined with prismatic boundary layer elements for resolving thin skin depths and using an adaptive proper orthogonal decomposition (POD) reduced-order modelling methodology to accelerate computations for varying parameters.

Findings

The success of the proposed methodologies is demonstrated using a series of examples. A significant reduction in computational effort is observed across all examples. The authors identify and recommend a simple discretisation strategy and improved accuracy is obtained using adaptive POD.

Originality/value

The authors present novel computations, timings and error certificates of MPT characterisations of realistic objects made of magnetic materials. A novel postprocessing implementation is introduced and an adaptive POD algorithm is demonstrated.

Details

Engineering Computations, vol. 41 no. 10
Type: Research Article
ISSN: 0264-4401

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Book part
Publication date: 30 January 2025

Seyi S. Stephen, Ayodeji E. Oke, Clinton O. Aigbavboa, Opeoluwa I. Akinradewo, Pelumi E. Adetoro and Matthew Ikuabe

This chapter explored health and safety considerations in stealth construction, emphasising the integration of advanced technologies and innovative practices. It commences with a…

Abstract

This chapter explored health and safety considerations in stealth construction, emphasising the integration of advanced technologies and innovative practices. It commences with a general introduction, followed by a historical overview of safety practices in the construction industry, highlighting the evolution of a safety culture. The chapter examined various health and safety management techniques, including policy formulation, safety training programs, and job safety analysis. Additionally, it discussed current trends such as wearable technology, IoT, VR/AR, and predictive analytics. The unique requirements of stealth construction are addressed, focusing on building cross-section design, visibility, application of radio frequency emission and countermeasures. Finally, it presents a comprehensive approach to achieving stealth construction, emphasising environmental protection, safety, speed, economy, and aesthetics, and provides practical examples to illustrate these concepts.

Details

Stealth Construction: Integrating Practices for Resilience and Sustainability
Type: Book
ISBN: 978-1-83608-183-8

Keywords

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