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1 – 10 of over 2000
Article
Publication date: 25 October 2022

Siwen Wang and Qiyou Cheng

Computational fluid dynamics (CFD)/computational structural dynamics (CSD) coupling analysis is an important method in the research of helicopter aeroelasticity due to its high…

Abstract

Purpose

Computational fluid dynamics (CFD)/computational structural dynamics (CSD) coupling analysis is an important method in the research of helicopter aeroelasticity due to its high precision. However, this method still suffers from some problems, such as wake dissipation and large computational cost. In this study, a new coupling method and a new air load correction method that combine the free wake model with the CFD/CSD method are proposed to maintain computational efficiency whilst solving the wake dissipation problem of the prior coupling methods.

Design/methodology/approach

A new coupling method and a new air load correction method that combine the free wake model with the CFD/CSD method are proposed. With the introduction of the free wake model, the CFD solver can adopt two-order accuracy schemes and fewer aerodynamic grids, thus maintaining computational efficiency whilst solving the wake dissipation problem of the prior coupling methods.

Findings

Compared with the predictions of the prior methods and flight test data, those of the proposed method are more accurate and closer to the test data. The difference between the two methods in high-speed forward flight is minimal.

Research limitations/implications

Because of the chosen research approach, the research results may lack generalisability. Therefore, researchers are encouraged to test the proposed method further.

Originality/value

In this paper, a CFD/CSD/free wake coupling method is proposed to improve the computational accuracy of the traditional CFD/CSD coupled method and ensure the computational efficiency.

Details

Aircraft Engineering and Aerospace Technology, vol. 95 no. 1
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 13 June 2016

Sayed M. Derakhshani, Dingena L. Schott and Gabriel Lodewijks

The macroscopic properties of dried sand can be correctly modelled when the accurate determination of the microscopic properties is available. The microscopic properties between…

353

Abstract

Purpose

The macroscopic properties of dried sand can be correctly modelled when the accurate determination of the microscopic properties is available. The microscopic properties between the particles such as the coefficients of rolling (µ r) and sliding (µ s), are numerically determined in two different ways: with and without considering the fluid effect. In an earlier study, the microscopic properties were determined by discrete element method (DEM) and without considering the air effect on the macroscopic properties such as the Angle of Repose. The purpose of this paper is to recalibrate the microscopic properties through a coupling between the DEM and computational fluid dynamics (CFD).

Design/methodology/approach

The first step is dedicated to the calibration of the CFD-DEM model through modelling a single particle sedimentation within air, water, and silicon oil. The voidage and drag models, the grid size ratio (D/dx), the domain size ratio (W/D), and the optimum coupling interval between the CFD and DEM were investigated through comparing the CFD-DEM results with the analytical solution and experimental data. The next step is about modelling an Hourglass with the calibrated CFD-DEM model to recalibrate the µ r and µ s of dried sand particles.

Findings

It was concluded that the air has a minor effect on the macroscopic properties of the dried sand and the µ r and µ s that were obtained with the DEM can be utilized in the CFD-DEM simulation.

Originality/value

Utilizing the granulometry of dried quartz sand in the calibration process of the CFD-DEM method has raised the possibility of using the µ r and µ s for other applications in future studies.

Details

Engineering Computations, vol. 33 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 11 March 2020

Hamidreza Khodayari, Fathollah Ommi and Zoheir Saboohi

The purpose of this paper is to review the applications of the chemical reactor network (CRN) approach for modeling the combustion in gas turbine combustors and classify the CRN…

609

Abstract

Purpose

The purpose of this paper is to review the applications of the chemical reactor network (CRN) approach for modeling the combustion in gas turbine combustors and classify the CRN construction methods that have been frequently used by researchers.

Design/methodology/approach

This paper initiates with introducing the CRN approach as a practical tool for precisely predicting the species concentrations in the combustion process with lower computational costs. The structure of the CRN and its elements as the ideal reactors are reviewed in recent studies. Flow field modeling has been identified as the most important input for constructing the CRNs; thus, the flow field modeling methods have been extensively reviewed in previous studies. Network approach, component modeling approach and computational fluid dynamics (CFD), as the main flow field modeling methods, are investigated with a focus on the CRN applications. Then, the CRN construction approaches are reviewed and categorized based on extracting the flow field required data. Finally, the most used kinetics and CRN solvers are reviewed and reported in this paper.

Findings

It is concluded that the CRN approach can be a useful tool in the entire process of combustion chamber design. One-dimensional and quasi-dimensional methods of flow field modeling are used in the construction of the simple CRNs without detailed geometry data. This approach requires fewer requirements and is used in the initial combustor designing process. In recent years, using the CFD approach in the construction of CRNs has been increased. The flow field results of the CFD codes processed to create the homogeneous regions based on construction criteria. Over the past years, several practical algorithms have been proposed to automatically extract reactor networks from CFD results. These algorithms have been developed to identify homogeneous regions with a high resolution based on the splitting criteria.

Originality/value

This paper reviews the various flow modeling methods used in the construction of the CRNs, along with an overview of the studies carried out in this field. Also, the usual approaches for creating a CRN and the most significant achievements in this field are addressed in detail.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 4
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 5 August 2020

Moeti Masiane, Eric Jacques, Wuchun Feng and Chris North

The purpose of this paper is to collect data from humans as they generate insights from the visualised results of computational fluid dynamics (CFD) scientific simulation. The…

Abstract

Purpose

The purpose of this paper is to collect data from humans as they generate insights from the visualised results of computational fluid dynamics (CFD) scientific simulation. The authors hypothesise the behaviour of their insight errors (IEs) and proceed to quantify the IEs provided by the crowd participants. They then use the insight framework to model the behaviours of the errors. Using the crowd responses and models from the framework, they test the hypotheses and use the results to validate the framework for the speedup of CFD applications.

Design/methodology/approach

The authors use a randomised between-subjects experiment with blocking. CFD grid resolution is the independent variable while IE is the dependent variable. The experiment has one treatment factor with five levels. In case varying timestamps has an effect on insight variance levels, the authors block the responses by timestep. In total, 150 participants are randomly assigned to one of five groups and also randomly assigned to one of five blocks within a treatment. Participants are asked to complete a benchmark and open-ended task.

Findings

The authors find that the variances of insight and perception errors have a U-shaped relationship with grid resolution, that similar to the previously studied visualisation applications, the IE framework is valid for insights generated from CFD results and grid resolution can be used to predict the variance of IE resulting from observing CFD post-processing results.

Originality/value

To the best of the authors’ knowledge, no other work has measured IE variance to present it to simulation users so that they can use it as a feedback metric for selecting the ideal grid resolution when using grid resolution to speedup CFD simulation.

Details

Journal of Engineering, Design and Technology , vol. 19 no. 1
Type: Research Article
ISSN: 1726-0531

Keywords

Article
Publication date: 7 June 2023

Hafiz Muhammad Muien, Sabariah Nordin and Bazeet Olayemi Badru

As the benefit of gender diversity continues to receive significant attention, a holistic investigation of its effect on corporate financial distress (CFD) is lacking. Therefore…

Abstract

Purpose

As the benefit of gender diversity continues to receive significant attention, a holistic investigation of its effect on corporate financial distress (CFD) is lacking. Therefore, this study examines the effects of board gender diversity, measured in different forms, such as the presence and proportion of female directors, family-affiliated female directors and the chief executive officer (CEO) gender, on CFD in Pakistan. The study also investigates the interacting effects of family-controlled (20 and 50% family-owned) companies on the association between board gender diversity and CFD.

Design/methodology/approach

The study applied the pooled cross-sectional logistic regression model to examine the effect of board gender diversity (presence and proportion of female directors, family-affiliated female directors and CEO gender) on CFD through a sample of 285 non-financial companies in Pakistan over the period of 2006–2017.

Findings

The results reveal that gender diversity on boards is significantly and negatively associated with CFD in Pakistan. In addition, when family ownership is 50% or more, the interacting effect of family control is found to be significant, while gender effects remain negative. The results suggest that female directors contribute to the long-term viability of companies, especially family-owned companies. Female directors are also found to be more prevalent in family-owned companies compared to their non-family counterparts.

Research limitations/implications

The findings imply that female directors may efficiently manage and control all functions necessary to guarantee the company's long-term prosperity. Similarly, gender effects can outweigh the detrimental impact of family control when female directors are in reasonable numbers and of high quality in the boardroom.

Practical implications

The practical relevance of the findings is that female directors play a significant role on the corporate board. Thus, it is a wakeup call for Pakistani companies to recognize the critical role and uniqueness of women on the corporate ladder. Family companies can also galvanize on the uniqueness of women to improve their governance structure.

Originality/value

This study adds to the literature on the benefits of gender diversity in family and non-family-owned companies. Specifically, this study applied multiple measures of gender diversity and family control in a single study. In addition, the study was conducted in a country that is ranked as the second worst country in the Global Gender Gap Index 2022, implying that investigating this type of research would go a long way towards changing the minds of corporate executives and regulators about the critical role that women can play in the economy.

Details

Journal of Family Business Management, vol. 14 no. 1
Type: Research Article
ISSN: 2043-6238

Keywords

Article
Publication date: 11 March 2020

Weiwei Li, Jin-Lou Zhao, Linxiao Dong and Chong Wu

Long-term contract is an important developing direction of China's coal industry coordination. This paper aims to discuss how to use contract for difference (CFD) to avoid risk…

Abstract

Purpose

Long-term contract is an important developing direction of China's coal industry coordination. This paper aims to discuss how to use contract for difference (CFD) to avoid risk and effectively increase the benefit of both coal and thermal power plants in the coal-electricity supply chain.

Design/methodology/approach

Based on prospect theory, this paper takes the risks and benefits of the coal and coal-fired power plants in the coal supply chain under CFD into balanced consideration to construct the contract coordination mechanism. In this mechanism, the coal demand in the coal supply chain equilibrium under centralized decision-making is regarded as the total annual volume of transactions needed to design the contract coordination mechanism and solve double marginalization. Then, based on prospect theory, in the construction of CFD, this paper takes the income of power and coal enterprises when they are in equilibrium under Stackelberg non-cooperative game as the reference point. In addition, considering that coal demand is a random variable, the CFD with a one-year trading session can be designed.

Findings

The research derives the coal price of the contract for difference, contract trading volume and its proportion of the total trading volume. A numerical example shows that the model above can be used to effectively avoid the risk of both coal and electricity sides.

Originality/value

To solve the conflict between coal enterprises and thermal power plants, let the coal-electricity supply chain be converted from non-cooperative game to cooperative game. Based on the prospect theory, this paper takes the income of the non-cooperative game of coal and thermal power plants as a reference point and considers how to design the coordination mechanism, the contract for difference, so as to make the two parties cooperate to solve the double marginal utility of the non-cooperative game in a chain supply. The main innovation of the work lies in the following: first, the coal demand when the coal-electrical supply chain is in balance under centralized decision-making is taken as the total annual trading volume needed to design the contract coordination mechanism and solve double marginalization. Second, based on prospect theory, in the construction of CFD, the benefits of coal-fired power plants and coal enterprises when both sides are in equilibrium under the Stackelberg non-cooperative game are taken as the reference points, and coal demand is taken as a random variable to design the CFD with a one-year transaction period. The price of coal that is not traded through CFD is calculated according to the daily market price. Third, this paper proposes the prospect M-V criterion of the risk-benefit equilibrium of both power and coal enterprises, which means that the risk-benefit equilibrium of both sides is the prospect variance effect of both sides relative to the reference point benefit divided by the prospect expectation effect.

Details

Kybernetes, vol. 50 no. 1
Type: Research Article
ISSN: 0368-492X

Keywords

Article
Publication date: 21 May 2021

Marion Charlier, Antoine Glorieux, Xu Dai, Naveed Alam, Stephen Welch, Johan Anderson, Olivier Vassart and Ali Nadjai

The purpose of this paper is to propose a simplified representation of the fire load in computational fluid dynamics (CFD) to represent the effect of large-scale travelling fire…

654

Abstract

Purpose

The purpose of this paper is to propose a simplified representation of the fire load in computational fluid dynamics (CFD) to represent the effect of large-scale travelling fire and to highlight the relevance of such an approach whilst coupling the CFD results with finite element method (FEM) to evaluate related steel temperatures, comparing the numerical outcomes with experimental measurements.

Design/methodology/approach

This paper presents the setup of the CFD simulations (FDS software), its corresponding assumptions and the calibration via two natural fire tests whilst focusing on gas temperatures and on steel temperatures measured on a central column. For the latter, two methods are presented: one based on EN 1993-1-2 and another linking CFD and FEM (SAFIR® software).

Findings

This paper suggests that such an approach can allow for an acceptable representation of the travelling fire both in terms of fire spread and steel temperatures. The inevitable limitations inherent to the simplifications made during the CFD simulations are also discussed. Regarding steel temperatures, the two methods lead to quite similar results, but with the ones obtained via CFD–FEM coupling are closer to those measured.

Originality/value

This work has revealed that the proposed simplified representation of the fire load appears to be appropriate to evaluate the temperature of steel structural elements within reasonable limits on computational time, making it potentially desirable for practical applications. This paper also presents the first comparisons of FDS–SAFIR® coupling with experimental results, highlighting promising outcomes.

Details

Journal of Structural Fire Engineering, vol. 12 no. 3
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 17 October 2008

R. Aghaei tog, A.M. Tousi and A. Tourani

The purpose of this paper is to show the superior turbulence method in CFD analysis of radial turbo machines and to introduce the best way to choose turbulence parameters whenever…

2504

Abstract

Purpose

The purpose of this paper is to show the superior turbulence method in CFD analysis of radial turbo machines and to introduce the best way to choose turbulence parameters whenever FLUENT user applies this software as a complementary design tool for high‐speed turbo machinery components.

Design/methodology/approach

One of the most important issues in CFD is analysis of flow field in turbo machines. Flow in high‐speed radial turbo machinery is a 3D, turbulent and unsteady behavior so needs suitable method for converging. It is clear that the turbulence model has an extraordinary effect on investigation of 3D flows in high‐speed turbo machinery. A centrifugal compressor of micro and radial turbines have been designed and simulated 3D using the commercial CFD‐code FLUENT 6. Three turbulence models kε/standard, renormalization‐group (RNG) and RSM were considered and results of three models were compared with experimental and 1D design results.

Findings

The study showed numerical results are compatible with experimental performance data. It determined that RNG method in CFD analysis of radial turbo machines has provided better results than the standard kε method. In addition, when using the RNG method, the phenomena of flow field were more visible than other methods.

Originality/value

This paper offers use of the RNG method as a superior turbulence method in CFD analysis of radial turbo machines.

Details

Aircraft Engineering and Aerospace Technology, vol. 80 no. 6
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 12 September 2016

Nicola Tondini, Andrea Morbioli, Olivier Vassart, Sullivan Lechêne and Jean-Marc Franssen

This paper aims to present the assumptions and the issues that arise when developing an integrated modelling methodology between a computational fluid dynamics (CFD) software…

Abstract

Purpose

This paper aims to present the assumptions and the issues that arise when developing an integrated modelling methodology between a computational fluid dynamics (CFD) software applied to compartment fires and a finite element (FE) software applied to structural systems.

Design/methodology/approach

Particular emphasis is given to the weak coupling approach developed between the CFD code fire dynamics simulator (FDS) and the FE software SAFIR. Then, to show the potential benefits of such a methodology, a multi-storey steel-concrete composite open car park was considered.

Findings

Results show that the FDS–SAFIR coupling allows overcoming shortcomings of simplified models by performing the thermal analysis in the structural elements based on a more advanced modelling of the fire development, whereas it appears that the Hasemi model is more conservative in terms of thermal action.

Originality/value

A typical design approach using the Hasemi model is compared with a more advanced analysis that relies on the proposed FDS–SAFIR coupling.

Details

Journal of Structural Fire Engineering, vol. 7 no. 3
Type: Research Article
ISSN: 2040-2317

Keywords

Article
Publication date: 5 April 2019

Corrado Groth, Ubaldo Cella, Emiliano Costa and Marco Evangelos Biancolini

This paper aims to present a fast and effective approach to tackle complex fluid structure interaction problems that are relevant for the aeronautical design.

Abstract

Purpose

This paper aims to present a fast and effective approach to tackle complex fluid structure interaction problems that are relevant for the aeronautical design.

Design/methodology/approach

High fidelity computer-aided engineering models (computational fluid dynamics [CFD] and computational structural mechanics) are coupled by embedding modal shapes into the CFD solver using RBF mesh morphing.

Findings

The theoretical framework is first explained and its use is then demonstrated with a review of applications including both steady and unsteady cases. Different flow and structural solvers are considered to showcase the portability of the concept.

Practical implications

The method is flexible and can be used for the simulation of complex scenarios, including components vibrations induced by external devices, as in the case of flapping wings.

Originality/value

The computation mesh of the CFD model becomes parametric with respect to the modal shape and, so, capable to self-adapt to the loads exerted by the surrounding fluid both for steady and transient numerical studies.

Details

Aircraft Engineering and Aerospace Technology, vol. 91 no. 6
Type: Research Article
ISSN: 1748-8842

Keywords

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