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Article
Publication date: 28 November 2023

Waqar Khan Usafzai, Ioan Pop and Cornelia Revnic

This paper aims to present dual solutions for the two-dimension copper oxide with silver (CuO–Ag) and zinc oxide with silver (ZnO–Ag) hybrid nanofluid flow past a permeable…

Abstract

Purpose

This paper aims to present dual solutions for the two-dimension copper oxide with silver (CuO–Ag) and zinc oxide with silver (ZnO–Ag) hybrid nanofluid flow past a permeable shrinking sheet in a dusty fluid with velocity slip.

Design/methodology/approach

The governing partial differential equations for the two dust particle phases are reduced to the pertinent ordinary differential equations using a similarity transformation. Closed-form analytical solutions for the reduced skin friction and reduced Nusselt number, as well as for the velocity and temperature profiles, were presented, both graphically and in tables, under specific non-dimensional physical parameters such as the suction parameter, Prandtl number, slip parameter and shrinking parameter, which are also presented in both figures and tables.

Findings

The results indicate that for the shrinking flow, the wall skin friction is higher in the dusty fluid when compared with the clear (viscous) fluid. In addition, the effect of the fluid–particle interaction parameter to the fluid phase can be seen more clearly in the shrinking flow. Furthermore, multiple (dual, upper and lower branch solutions) are found for the governing similarity equations and the upper branch solution expanded with higher values of the suction parameter. It can be confirmed that the lower branch solution is unstable.

Practical implications

In practice, the study of the stretching/shrinking flow is crucially important and useful. Both the problems of steady and unsteady flow of a dusty fluid have a wide range of possible applications in practice, such as in the centrifugal separation of particles, sedimentation and underground disposal of radioactive waste materials.

Originality/value

Even though the problem of dusty fluid has been broadly investigated, very limited results can be found for a shrinking sheet. Indeed, this paper has succeeded to obtain analytically dual solutions. The stability analysis can be performed by following many published papers on stretching/shrinking sheets. Finally, the critical values and plotting curves for obtaining single or dual solution are successfully presented.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 34 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 9 January 2024

Kathiravan Balusamy, Vinothraj A. and Suresh V.

The purpose of this study is to explore the effects of aerospike and hemispherical aerodisks on flow characteristics and drag reduction in supersonic flow over a blunt body…

Abstract

Purpose

The purpose of this study is to explore the effects of aerospike and hemispherical aerodisks on flow characteristics and drag reduction in supersonic flow over a blunt body. Specifically, the study aims to analyze the impact of varying the length of the cylindrical rod in the aerospike (ranging from 0.5 to 2.0 times the diameter of the blunt body) and the diameter of the hemispherical disk (ranging from 0.25 to 0.75 times the blunt body diameter). CFD simulations were conducted at a supersonic Mach number of 2 and a Reynolds number of 2.79 × 106.

Design/methodology/approach

ICEM CFD and ANSYS CFX solver were used to generate the three-dimensional flow along with its structures. The flow structure and drag coefficient were computed using Reynolds-averaged Navier–Stokes equation model. The drag reduction mechanism was also explained using the idea of dividing streamline and density contour. The performance of the aero spike length and the effect of aero disk size on the drag are investigated.

Findings

The separating shock is located in front of the blunt body, forming an effective conical shape that reduces the pressure drag acting on the blunt body. It was observed that extending the length of the spike beyond a specific critical point did not impact the flow field characteristics and had no further influence on the enhanced performance. The optimal combination of disk and spike length was determined, resulting in a substantial reduction in drag through the introduction of the aerospike and disk.

Research limitations/implications

To predict the accurate results of drag and to reduce the simulation time, a hexa grid with finer mesh structure was adopted in the simulation.

Practical implications

The blunt nose structures are primarily employed in the design of rockets, missiles, and re-entry capsules to withstand higher aerodynamic loads and aerodynamic heating.

Originality/value

For the optimized size of the aero spike, aero disk is also optimized to use the benefits of both.

Details

Aircraft Engineering and Aerospace Technology, vol. 96 no. 2
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 1 March 2023

Natalia C. Roşca, Alin V. Roşca and Ioan Pop

This paper aims to present the steady dual solutions on three-dimensional flow and heat transfer of nanofluid over a permeable non-linearly shrinking surface with two-order…

Abstract

Purpose

This paper aims to present the steady dual solutions on three-dimensional flow and heat transfer of nanofluid over a permeable non-linearly shrinking surface with two-order velocity slips conditions. Boundary layer assumption is considered in the mathematical modelling. Authors comprehend from previous studies and papers that the shrinking surfaces are extremely important in current engineering and environmental systems.

Design/methodology/approach

Using appropriate similarity variables, the full partial differential equations (PDF) are modified into a specific set of ordinary (similar) differential equations (ODE). The resulting non-linear ordinary differential system is then solved both analytically for some particular cases and numerically for the general case using the function bvp4c from MATLAB for characteristic values of the parameters which govern the equations. The transformed mathematical model is analysed using the bvp4c procedure. Based on the given assumptions, this study is able to produce multiple solutions of the problem.

Findings

The ordinary (similarity) differential equations have two branches solutions, upper and lower branch solutions, given some interval of shrinking and velocity slip parameters. The authors consider here a temporal stability analysis, as they want to establish which of the solutions are stable and which are not. In a distinct paragraph, the authors discuss in detail and present in a graphical manner the effects of shrinking and second-order slip flow model on the skin friction coefficient, surface wall heat flux and dimensionless velocity and temperature profiles. The analysis reveals that the second order slip has a big influence on the flow and heat transfer characteristics.

Originality/value

The present discoveries are unique and truly new for the research of the three-dimensional stretching/shrinking forced convection flow and heat transfer nanofluids. The nanofluid is a water-based nanofluid (H2O), which contains one type of nanoparticles, namely, copper (Cu). Of course, the analysis can be further extended considering other types of nanoparticles such as alumina (Al2O3). The authors assume that the thermal equilibrium is reached for the base fluid together with the suspended nanoparticles and that the nanoparticles are uniform in dimension and form.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 33 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 23 October 2023

Gorakh Nath and Abhay Maurya

The purpose of the present article is to obtain the similarity solution for the shock wave generated by a piston propagating in a self-gravitating nonideal gas under the impact of…

Abstract

Purpose

The purpose of the present article is to obtain the similarity solution for the shock wave generated by a piston propagating in a self-gravitating nonideal gas under the impact of azimuthal magnetic field for adiabatic and isothermal flows.

Design/methodology/approach

The Lie group theoretic method given by Sophus Lie is used to obtain the similarity solution in the present article.

Findings

Similarity solution with exponential law shock path is obtained for both ideal and nonideal gas cases. The effects on the flow variables, density ratio at the shock front and shock strength by the variation of the shock Cowling number, adiabatic index of the gas, gravitational parameter and nonidealness parameter are investigated. The shock strength decreases with an increase in the shock Cowling number, nonidealness parameter and adiabatic index, whereas the strength of the shock wave increases with an increase in gravitational parameter.

Originality/value

Propagation of shock wave with spherical geometry in a self-gravitating nonideal gas under the impact of azimuthal magnetic field for adiabatic and isothermal flows has not been studied by any author using the Lie group theoretic method.

Details

Engineering Computations, vol. 40 no. 9/10
Type: Research Article
ISSN: 0264-4401

Keywords

Book part
Publication date: 4 September 2023

Vasuki Shastry

Abstract

Details

The Notorious ESG
Type: Book
ISBN: 978-1-80455-545-3

Open Access
Article
Publication date: 10 February 2023

Mario Rapaccini, Marco Paiola, Lino Cinquini and Riccardo Giannetti

This study aims to investigate the contribution of knowledge-intensive business services firms to small- and medium-sized manufacturers’ digital servitization journeys, addressing…

1796

Abstract

Purpose

This study aims to investigate the contribution of knowledge-intensive business services firms to small- and medium-sized manufacturers’ digital servitization journeys, addressing the standardization versus customization dichotomy of services and solutions provision.

Design/methodology/approach

To identify the challenges that small- and medium-sized firms must face in the digital servitization journey and the role that knowledge-intensive business services firms may play in the innovation processes, the authors conduct a review on two still unrelated literature streams and develop a longitudinal single-case study, with a particular focus on knowledge generation mechanisms.

Findings

Digital servitization is a particularly challenging transformational journey for minor firms. Knowledge-intensive business services firms can act as sources, facilitators, and carriers of knowledge, and they can orchestrate further contributions of other external partners and firms.

Research limitations/implications

The paper contributes to theory describing the roadmap and the role of external service providers in digital servitization journeys of smaller firms’, that are frequently excluded from mainstream research although being the backbone of European economies.

Practical implications

Digital servitization in minor manufacturing firms requires a long-term orientation and a multi-stage roadmap. Mixing standardized technology-based solutions and complementary professional services, knowledge-intensive business services firms can significantly contribute to lowering the journey’s uncertainties, operational complexity, and costs.

Originality/value

The paper sheds lights on how the collaboration between knowledge-intensive business services firms and small manufacturers generates novel knowledge and capabilities that contribute to takle the challenges of the different stages of the digital servitization roadmap.

Details

Journal of Business & Industrial Marketing, vol. 38 no. 6
Type: Research Article
ISSN: 0885-8624

Keywords

Book part
Publication date: 6 June 2023

Javier Vidal Olivares

During the 1920s, military interests in Latin America and international and diplomatic relations gave the impetus to the creation national airlines. In countries like Colombia and…

Abstract

During the 1920s, military interests in Latin America and international and diplomatic relations gave the impetus to the creation national airlines. In countries like Colombia and Brazil, the technological and commercial approaches of Germany and other Europeans nations influenced the forms airlines took. In the following decade the United States began to exert its influence which was consolidated after the Second World War. The pattern continued until the 1980s and involved strong international regulation, the predominance of publicly owned national airlines, and American technological leadership. Market liberalization then brought about a new scenario involving privatizations of national airlines across the region, intensified competition, and mergers and acquisitions that led to the formation of large carriers. Today, passenger traffic in the region is dominated by two carriers: LATAM and Avianca. Other local airlines remain, often linked to a global alliance member. Air traffic has been grown, with the prospect of further growth after economic recovery flowing the COVID-19 pandemic. Historically, commercial air traffic has adapted to the needs of its vast territory but where institutional changes have played a very important and often decisive role.

Details

Airlines and Developing Countries
Type: Book
ISBN: 978-1-80455-861-4

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