Muhammad Faisal Javed, Mohammed Jameel, Muhammad Ijaz Khan, Sumaira Qayyum, Niaz B. Khan and Tufail Ahmad Khan
This study aims to focus on second grade fluid flow over a rotating disk in the presence of chemical reaction. Uniform magnetic field is also taken into account. Because of the…
Abstract
Purpose
This study aims to focus on second grade fluid flow over a rotating disk in the presence of chemical reaction. Uniform magnetic field is also taken into account. Because of the smaller magnetic Reynolds number, induced magnetic field is negligible. Heat equation is constructed by considering heat source/sink.
Design/methodology/approach
Suitable variables are used to transform nonlinear partial differential equations to ordinary ones. Convergent series solutions are attained by applying homotopy analysis method.
Findings
Trends of different parameters on concentration, velocity and temperature are shown graphically. Skin friction coefficient and local Nusselt number are calculated and investigated under the effect of elaborated parameters. An elevation in the value of magnetic field parameter causes collapse in the velocity distributions. Velocity distribution in increasing function of viscoelastic parameter. Temperature and concentration profiles are decreasing functions of viscoelastic parameter. Concentration distribution reduces by increasing the chemical reaction parameter. There is more surface drag force for larger M, while opposite behavior is noted for β.
Originality/value
To the best of the authors’ knowledge, such consideration is yet to be published in the literature.
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Muhammad Ijaz Khan, Madiha Rashid, Tasawar Hayat, Niaz B. Khan and Ahmed Alsaedi
This paper aims to examine the three-dimensional (3D) flow of carbon nanotubes (CNTs) due to bidirectional nonlinearly stretching surface by considering porous medium…
Abstract
Purpose
This paper aims to examine the three-dimensional (3D) flow of carbon nanotubes (CNTs) due to bidirectional nonlinearly stretching surface by considering porous medium. Characteristics of both single-walled CNTs and multi-walled CNTs are discussed by considering Xue model. Darcy–Forchheimer model is used for flow saturating porous medium.
Design/methodology/approach
Optimal homotopy analysis method is used for the development of series solutions.
Findings
The authors deal with 3D Darcy–Forchheimer flow of CNTs over a nonlinearly stretching surface. Heat transport mechanism is discussed in the presence of Xue model. The homogeneous and heterogeneous effects are also accounted. The mathematical modeling is computed using boundary-layer approximations.
Originality/value
No such work has been done yet in the literature.
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Muhammad Waqas, M. Mudassar Gulzar, Waqar Azeem Khan, Muhammad Ijaz Khan and Niaz B. Khan
This paper aims to elaborate the characteristics of magneto-Maxwell nanoliquid toward moving radiated surface. Flow analysis subject to Darcy–Forchheimer concept is studied…
Abstract
Purpose
This paper aims to elaborate the characteristics of magneto-Maxwell nanoliquid toward moving radiated surface. Flow analysis subject to Darcy–Forchheimer concept is studied. Newtonian heat/mass conditions and heat source aspects are taken into account for modeling. Apposite transformations are introduced for non-dimensionalization process.
Design/methodology/approach
Optimal homotopy analysis method is implemented to compute convergent solutions of nonlinear ordinary differential equations.
Findings
Temperature field increments when thermophoresis, heat generation and Brownian movement parameters are increased, whereas reverse situation is noticed for larger Prandtl number. The results also witness that concentration distribution has opposite characteristics for larger thermophoresis and Brownian movement parameters. Furthermore, the presented analysis reduces to traditional Darcy relation in the absence of local inertia coefficient.
Originality/value
As per the authors’ knowledge, no such analysis has been yet reported.
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Niaz B. Khan, Zainah B. Ibrahim, Mian Ashfaq Ali, Mohammed Jameel, Muhammad Ijaz Khan, Ahad Javanmardi and D.O. Oyejobi
Over the past few decades, the flow around circular cylinders has been one of the highly researched topics in the field of offshore engineering and fluid-structure interaction…
Abstract
Purpose
Over the past few decades, the flow around circular cylinders has been one of the highly researched topics in the field of offshore engineering and fluid-structure interaction (FSI). In the current study, numerical simulations for flow around a fixed circular cylinder are performed at Reynolds number (Re) = 3900 with the LES method using the ICEM-CFD and ANSYS Fluent tool for meshing and analysis, respectively. Previously, similar studies have been conducted at the same Reynolds number, but there have been discrepancies in the results, particularly in calculating the recirculation length and angle of separation. In addition, the purpose of this study is to address the impact of time interval averaging to obtain the fully converged solution.
Design/methodology/approach
This study presents the LES method, using the ICEM-CFD and ANSYS fluent tool for meshing and analysis.
Findings
In the current study, turbulence statistics are sampled for 25, 50, 75 and 100 vortex-shedding cycles with the CFL value O (1). The recirculation length, angle of separation, hydrodynamic coefficients and the wake behind the cylinder are investigated up to ten diameters. The drag coefficient and Strouhal number are observed to be less sensitive, whereas the recirculation length appeared to be highly dependent on the average time statistics and the non-dimensional time step. Similarly, the mean streamwise and cross-flow velocity are observed to be sensitive to the average time statistics and non-dimensional time step in the wake region near the cylinder.
Originality/value
In the current investigation, turbulence statistics are sampled for 25, 50, 75 and 100 vortex-shedding cycles with the CFL value O (1), using large eddy simulation method at Re = 3900 around a circular cylinder. The impact of time interval averaging to obtain the fully converged mean flow field is addressed. No such consideration is yet published in the literature.
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Srinivasan Raghavan, Jan Dzugan, Sylwia Rzepa, Pavel Podany, Norman Soh, Lim Jia Hao and Niaz Khan
This study aims to investigate the effect of the wall thickness, deposition orientation and two different post-processing methods on the local mechanical properties and…
Abstract
Purpose
This study aims to investigate the effect of the wall thickness, deposition orientation and two different post-processing methods on the local mechanical properties and microstructure of additively manufactured parts made of maraging steel. In order to examine the local properties of the build, miniaturized testing specimens were employed. Before application of small-sized specimens, their performance was verified.
Design/methodology/approach
The investigation was composed of two stages. As first, the part thickness, specimen size and orientation were studied on a laser-powder bed fusion (L-PBF) platform with deposited walls of various thicknesses made of maraging steel. Subsequently, the influence of different heat-treatment methods was investigated on the final product, i.e. impellers. The miniaturized and standard tensile tests were performed to investigate the local mechanical properties. The porosity, microstructures and fracture surfaces were analysed by X-ray-computed tomography, X-ray diffraction and scanning electron microscopy with electron backscatter diffraction.
Findings
The results revealed good agreement between the values provided by miniaturized and standard specimens. The thinnest parts produced had the largest pores and the highest scatter of elongation values. In these cases, also the sub-contour porosity was observed. Part thickness affected pores’ size and results repeatability but not total porosity. The two-step heat-treatment (solutionizing and age-hardening) exhibited the highest yield and ultimate tensile strength.
Practical implications
The microstructure and local mechanical properties were studied on L-PBF platform with deposited walls of various thicknesses. Subsequently, a detailed analysis was conducted on real components (impellers) made of maraging steel, commonly used in tooling, automotive and aerospace industries.
Originality/value
The broadly understood quality of manufactured parts is crucial for their reliable and long-lasting operation. The findings presented in the manuscript allow the readers better understanding of the connection between deposition parameters, post-processing, microstructure and mechanical performance of additive manufacturing-processed parts.
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Khuram Ali Khan, Tasadduq Niaz, Đilda Pečarić and Josip Pečarić
In this work, we estimated the different entropies like Shannon entropy, Rényi divergences, Csiszár divergence by using Jensen’s type functionals. The Zipf’s–Mandelbrot law and…
Abstract
In this work, we estimated the different entropies like Shannon entropy, Rényi divergences, Csiszár divergence by using Jensen’s type functionals. The Zipf’s–Mandelbrot law and hybrid Zipf’s–Mandelbrot law are used to estimate the Shannon entropy. The Abel–Gontscharoff Green functions and Fink’s Identity are used to construct new inequalities and generalized them for
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Ataur Rahman Belal, Md. Rezaul Kabir, Stuart Cooper, Prasanta Dey, Niaz Ahmed Khan, Taiabur Rahman and Mohobbot Ali
Purpose – In this article, we examine the nature and the extent of corporate environmental and climate change disclosures in Bangladesh.Design/methodology/approach – For this…
Abstract
Purpose – In this article, we examine the nature and the extent of corporate environmental and climate change disclosures in Bangladesh.
Design/methodology/approach – For this purpose, we have undertaken a content analysis of annual reports related to the year 2008 and websites of the 100 largest companies (according to market capitalization) listed on the Dhaka Stock Exchange. We have used 24 content analysis categories to capture the relevant disclosures related to climate change and other environmental issues.
Findings – Key findings of our analysis suggest that the level of environmental and climate change disclosures is very low in Bangladesh. Although 91% of companies made disclosures in at least one category, most companies disclosed information only on the “energy usage” category, which is a mandatory requirement. Even fewer companies made disclosures in the specific areas of climate change. No disclosure was made in the significant categories such as GHG emissions. The second most popular category related to climate change was adaptation measures. Among the other environmental disclosures, a significant finding is that only 5% of (website 6%) companies disclosed that they had an effluent treatment plant. Closer examination of the nature of disclosures suggests that most of the disclosures are positive and descriptive in nature.
Originality/value – As far as we are aware, this is the first study of its kind in Bangladesh which systematically examines corporate climate change disclosures as a particular focus of research.
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Yan Baoxu and Kong Dejun
The amorphous Al-Ni-Fe-Gd coatings were fabricated to improve anti-corrosion performance of offshore platforms.
Abstract
Purpose
The amorphous Al-Ni-Fe-Gd coatings were fabricated to improve anti-corrosion performance of offshore platforms.
Design/methodology/approach
The amorphous Al-Ni-Fe-Gd coatings were first fabricated on S355 steel using the laser thermal spraying.
Findings
The amorphous forming capability and corrosion resistance increases with the laser powers increasing.
Research Limitations/implications
The amorphous Al-Ni-Fe-Gd coatings were applied on S355 steel of offshore platforms to increase its long-term heavy and anti-corrosion protection.
Originality/value
The amorphous Al-Ni-Fe-Gd coatings were first fabricated using a laser thermal spraying, improving its anti-corrosion.
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Dewan Mahboob Hossain and Md. Saiful Alam
The main objective of this article is to explore the discourses on social inequality in the annual reports of Bangladeshi NGOs.
Abstract
Purpose
The main objective of this article is to explore the discourses on social inequality in the annual reports of Bangladeshi NGOs.
Design/methodology/approach
To fulfil this objective, a discourse analysis was conducted on the latest annual reports of ten renowned NGOs in Bangladesh. The findings were interpreted from the impression management perspective.
Findings
It was found that the NGOs of Bangladesh are highlighting several social inequality issues such as poverty, gender inequality, inequality related to getting healthcare, legal and education facilities, etc. in their annual reports. Several impression management tactics were applied in the narratives of the annual reports. The NGOs portrayed themselves as “problem solvers” who are the saviors of distressed people.
Practical implications
This study will facilitate improving the understanding of NGO communication. Policymakers will be able to understand the disclosures of NGOs and consider the necessity to provide guidance that may lead to better information dissemination through reports.
Originality/value
This study will contribute to the limited literature on NGO disclosures from the context of developing economies. In the context of NGO, this research is methodologically novel as it applies discourse analysis and interprets the findings through the lens of impression management.