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1 – 10 of 36Hamza Sayyou, Jabrane Belabid, Hakan F. Öztop and Karam Allali
The purpose of this paper is to investigate the effects of gravitational modulation on natural convection in a square inclined porous cavity filled by a fluid containing copper…
Abstract
Purpose
The purpose of this paper is to investigate the effects of gravitational modulation on natural convection in a square inclined porous cavity filled by a fluid containing copper nanoparticles.
Design/methodology/approach
The present study uses a system of equations that couple hydrodynamics to heat transfer, representing the governing equations of fluid flow in a square domain. The Boussinesq–Darcy flow with Cu-water nanofluid is considered. The dimensionless partial differential equations are solved numerically using finite difference method based on alternating direction implicit scheme. The cavity is differentially heated by constant heat flux, while the top and bottom walls are insulated. The authors examined the effects of gravity amplitude (λ), vibration frequency (σ), tilt angle (α) and Rayleigh number (Ra) on flow and temperature.
Findings
The numerical simulations, in the form of streamlines, isotherms, Nusselt number and maximum stream function for different values of amplitude, frequency, tilt angle and Rayleigh number, have revealed an oscillatory behavior in the development of flow and temperature under gravity modulation. An increase of amplitude from 0.5 to 1 intensifies the flow stream (from |ψmax| = 21.415 to |ψmax| = 25.262) and improves heat transfer (from
Originality/value
To the best of the authors’ knowledge, this study is original in its examination of the combined effects of modulated gravity and cavity inclination on free convection in nanofluid porous media. It highlights the crucial roles of these two important factors in influencing flow and heat transfer properties.
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Nirmal K. Manna, Abhinav Saha, Nirmalendu Biswas and Koushik Ghosh
This paper aims to investigate the thermal performance of equivalent square and circular thermal systems and compare the heat transport and irreversibility of magnetohydrodynamic…
Abstract
Purpose
This paper aims to investigate the thermal performance of equivalent square and circular thermal systems and compare the heat transport and irreversibility of magnetohydrodynamic (MHD) nanofluid flow within these systems.
Design/methodology/approach
The research uses a constraint-based approach to analyze the impact of geometric shapes on heat transfer and irreversibility. Two equivalent systems, a square cavity and a circular cavity, are examined, considering identical heating/cooling lengths and fluid flow volume. The analysis includes parameters such as magnetic field strength, nanoparticle concentration and accompanying irreversibility.
Findings
This study reveals that circular geometry outperforms square geometry in terms of heat flow, fluid flow and heat transfer. The equivalent circular thermal system is more efficient, with heat transfer enhancements of approximately 17.7%. The corresponding irreversibility production rate is also higher, which is up to 17.6%. The total irreversibility production increases with Ra and decreases with a rise in Ha. However, the effect of magnetic field orientation (γ) on total EG is minor.
Research limitations/implications
Further research can explore additional geometric shapes, orientations and boundary conditions to expand the understanding of thermal performance in different configurations. Experimental validation can also complement the numerical analysis presented in this study.
Originality/value
This research introduces a constraint-based approach for evaluating heat transport and irreversibility in MHD nanofluid flow within square and circular thermal systems. The comparison of equivalent geometries and the consideration of constraint-based analysis contribute to the originality and value of this work. The findings provide insights for designing optimal thermal systems and advancing MHD nanofluid flow control mechanisms, offering potential for improved efficiency in various applications.
Graphical Abstract
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Arooj Tanveer, Sami Ul Haq, Muhammad Bilal Ashraf, Muhammad Usman Ashraf and R. Nawaz
This study aims to numerically investigate heat transport in a trapezoidal cavity using hybrid nanoparticles (Ag-$Al_2O_3$). Unlike previous studies, this one covers…
Abstract
Purpose
This study aims to numerically investigate heat transport in a trapezoidal cavity using hybrid nanoparticles (Ag-$Al_2O_3$). Unlike previous studies, this one covers magnetohydrodynamics, joule heating with viscous dissipation, heat absorption and generation. The left and right sides of the chasm are frigid. The upper wall heats, whereas the bottom wall remains adiabatic.
Design/methodology/approach
After reducing the system of dimensional equations to dimensionless equations, the authors use the Galerkin finite element method to solve them numerically. Geometric parameters affect heating efficiency; thus, the authors use flow metrics such as the Reynold number Re, magnetic parameter M, volume fraction coefficient, heat absorption and Eckert number Ec. The authors use the finite volume method to solve the governing equations after converting them to dimensionless form. The authors also try the artificial neural network method to predict the innovative cavity’s heat response in future scenarios. Transition state charts, regression analysis, MSE and error histograms accelerate, smooth and accurately converge solutions.
Findings
As the magnetic parameter and Eckert number increase, the enclosure emits more heat. As Reynold and volume fraction coefficients rise, the Nusselt number falls. It rose as magnetic, Eckert and heat absorption characteristics increased. The average Nusselt number rises with Reynolds and volume fraction coefficients. The magnetic, Eckert and heat absorption characteristics have inverse values.
Originality/value
This study numerically investigates heat transport in a trapezoidal cavity using hybrid nanoparticles (Ag-$Al_2O_3$). Unlike previous studies, this one covers MHD, joule heating with viscous dissipation, heat absorption and generation. The left and right sides of the chasm are frigid. The upper wall heats, whereas the bottom wall remains adiabatic.
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Manjeet Kumar, Pradeep Kaswan and Manjeet Kumari
The purpose of this paper is to showcase the utilization of the magnetohydrodynamics-microrotating Casson’s nanofluid flow model (MHD-MRCNFM) in examining the impact of an…
Abstract
Purpose
The purpose of this paper is to showcase the utilization of the magnetohydrodynamics-microrotating Casson’s nanofluid flow model (MHD-MRCNFM) in examining the impact of an inclined magnetic field within a porous medium on a nonlinear stretching plate. This investigation is conducted by using neural networking techniques, specifically using neural networks-backpropagated with the Levenberg–Marquardt scheme (NN-BLMS).
Design/methodology/approach
The initial nonlinear coupled PDEs system that represented the MRCNFM is transformed into an analogous nonlinear ODEs system by the adoption of similarity variables. The reference data set is created by varying important MHD-MRCNFM parameters using the renowned Lobatto IIIA solver. The numerical reference data are used in validation, testing and training sets to locate and analyze the estimated outcome of the created NN-LMA and its comparison with the corresponding reference solution. With mean squared error curves, error histogram analysis and a regression index, better performance is consistently demonstrated. Mu is a controller that controls the complete training process, and the NN-BLMS mainly concentrates on the higher precision of nonlinear systems.
Findings
The peculiar behavior of the appropriate physical parameters on nondimensional shapes is demonstrated and explored via sketches and tables. For escalating amounts of inclination angle and Brinkman number, a viable entropy profile is accomplished. The angular velocity curve grows as the rotation viscosity and surface condition factors rise. The dominance of friction-induced irreversibility is observed in the vicinity of the sheet, whereas in the farthest region, the situation is reversed with heat transfer playing a more significant role in causing irreversibilities.
Originality/value
To improve the efficiency of any thermodynamic system, it is essential to identify and track the sources of irreversible heat losses. Therefore, the authors analyze both flow phenomena and heat transport, with a particular focus on evaluating the generation of entropy within the system.
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Fatih Selimefendigil and Hakan F. Oztop
Multiple encapsulated phase change materials (PCMs) are used in a wide range of applications, including convective drying, electronic cooling, waste heat recovery and air…
Abstract
Purpose
Multiple encapsulated phase change materials (PCMs) are used in a wide range of applications, including convective drying, electronic cooling, waste heat recovery and air conditioning. Therefore, it is important to understand the performance of multiple PCMs in channels with flow separation and develop methods to increase their effectiveness. The aim of the study is to analyze the phase transition dynamics of multiple encapsulated PCMs mounted in a U-shaped tube under inclined magnetic field by using ternary nanofluid.
Design/methodology/approach
The PCMs used in the upper horizontal channel, vertical channel and lower horizontal channel are denoted by M1, M2 and M3. Magnetic field is uniform and inclined while finite element method is used as the solution technique. Triple encapsulated-PCM system study is carried out taking into account different values of Reynolds number (Re, ranges from 300 to 1,000), Hartmann number (Ha ranges from 0 and 60), magnetic field inclination (between 0 and 90) and solid volume fraction of ternary nanofluid (between 0 and 0.03). The dynamic response of the liquid fraction is estimated for each PCM with varying Re, Ha and t using an artificial neural network.
Findings
It is observed that for PCMs M2 and M3, the influence of Re on the phase transition is more effective. For M2 and M3, entire transition time (t-F) lowers by approximately 47% and 47.5% when Re is increased to its maximum value, whereas it only falls by 10% for M1. The dynamic characteristics of the phase transition are impacted by imposing MGF and varying its strength and inclination. When Ha is raised from Ha = 0 to Ha = 50, the t-F for PCM-M2 (PCM-M3) falls (increases) by around 30% (29%). For PCMs M1, M2 and M3, the phase transition process accelerates by around 20%, 30% and 28% when the solid volume fraction is increased to its maximum value.
Originality/value
Outcomes of this research is useful for understanding the phase change behavior of multiple PCMs in separated flow and using various methods such as nano-enhanced magnetic field to improve their effectiveness. Research outputs are beneficial for initial design and optimization of using multiple PCMs in diverse energy system technologies, including solar power, waste heat recovery, air conditioning, thermal management and drying.
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Baharak Hooshyarfarzin, Mostafa Abbaszadeh and Mehdi Dehghan
The main aim of the current paper is to find a numerical plan for hydraulic fracturing problem with application in extracting natural gases and oil.
Abstract
Purpose
The main aim of the current paper is to find a numerical plan for hydraulic fracturing problem with application in extracting natural gases and oil.
Design/methodology/approach
First, time discretization is accomplished via Crank-Nicolson and semi-implicit techniques. At the second step, a high-order finite element method using quadratic triangular elements is proposed to derive the spatial discretization. The efficiency and time consuming of both obtained schemes will be investigated. In addition to the popular uniform mesh refinement strategy, an adaptive mesh refinement strategy will be employed to reduce computational costs.
Findings
Numerical results show a good agreement between the two schemes as well as the efficiency of the employed techniques to capture acceptable patterns of the model. In central single-crack mode, the experimental results demonstrate that maximal values of displacements in x- and y- directions are 0.1 and 0.08, respectively. They occur around both ends of the line and sides directly next to the line where pressure takes impact. Moreover, the pressure of injected fluid almost gained its initial value, i.e. 3,000 inside and close to the notch. Further, the results for non-central single-crack mode and bifurcated crack mode are depicted. In central single-crack mode and square computational area with a uniform mesh, computational times corresponding to the numerical schemes based on the high order finite element method for spatial discretization and Crank-Nicolson as well as semi-implicit techniques for temporal discretizations are 207.19s and 97.47s, respectively, with 2,048 elements, final time T = 0.2 and time step size τ = 0.01. Also, the simulations effectively illustrate a further decrease in computational time when the method is equipped with an adaptive mesh refinement strategy. The computational cost is reduced to 4.23s when the governed model is solved with the numerical scheme based on the adaptive high order finite element method and semi-implicit technique for spatial and temporal discretizations, respectively. Similarly, in other samples, the reduction of computational cost has been shown.
Originality/value
This is the first time that the high-order finite element method is employed to solve the model investigated in the current paper.
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Syed Modassir Hussain, Rohit Sharma, Manoj Kumar Mishra and Jitendra Kumar Singh
Nanosized honeycomb-configured materials are used in modern technology, thermal science and chemical engineering due to their high ultra thermic relevance. This study aims to…
Abstract
Purpose
Nanosized honeycomb-configured materials are used in modern technology, thermal science and chemical engineering due to their high ultra thermic relevance. This study aims to scrutinize the heat transmission features of magnetohydrodynamic (MHD) honeycomb-structured graphene nanofluid flow within two squeezed parallel plates under Joule dissipation and solar thermal radiation impacts.
Design/methodology/approach
Mass, energy and momentum preservation laws are assumed to find the mathematical model. A set of unified ordinary differential equations with nonlinear behavior is used to express the correlated partial differential equations of the established models, adopting a reasonable similarity adjustment. An approximate convergent numerical solution to these equations is evaluated by the shooting scheme with the Runge–Kutta–Fehlberg (RKF45) technique.
Findings
The impression of pertinent evolving parameters on the temperature, fluid velocity, entropy generation, skin friction coefficients and the heat transference rate is explored. Further, the significance of the irreversibility nature of heat transfer due to evolving flow parameters are evaluated. It is noted that the heat transference rate performance is improved due to the imposition of the allied magnetic field, Joule dissipation, heat absorption, squeezing and thermal buoyancy parameters. The entropy generation upsurges due to rising magnetic field strength while its intensification is declined by enhancing the porosity parameter.
Originality/value
The uniqueness of this research work is the numerical evaluation of MHD honeycomb-structured graphene nanofluid flow within two squeezed parallel plates under Joule dissipation and solar thermal radiation impacts. Furthermore, regression models are devised to forecast the correlation between the rate of thermal heat transmission and persistent flow parameters.
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Toka Fahmy Aly, Salma Ehab and Yomna Amr Lotfi
Safety, one of the basic human needs for existence, is a very important factor in achieving a successful urban space. A lack of its presence could make it challenging for…
Abstract
Purpose
Safety, one of the basic human needs for existence, is a very important factor in achieving a successful urban space. A lack of its presence could make it challenging for residents of a place to live and function effectively. Therefore, this study aims to identify the urban design attributes that would potentially enhance the perceived sense of safety, mainly focusing on two case studies in El-Sherouk neighborhood in Cairo. The two selected case studies are considered car-oriented due to their reduced levels of safety.
Design/methodology/approach
This study was conducted through a set of data collection phases from field surveys and survey questionnaires that infer the influence of the surrounding urban environment on a specific target group. Statistical Package for the Social Sciences (SPSS) statistical analysis tool was used to analyze data collected from survey questionnaires.
Findings
Finally, by the end of this research, a set of urban design qualities vital for achieving the desired levels of safety were introduced. The findings of this study revealed key urban design qualities that can potentially contribute to enhancing the perceived sense of safety as they showed a strong positive correlation: (1) imageability, (2) transparency, (3) complexity and (4) human scale and enclosure. Moreover, multiple linear regression indicates that urban design qualities are strong predictors of perceived safety.
Originality/value
This study presents a holistic approach to studying the relationship between urban design and perceived safety by examining two case studies located in El-Sherouk City in Cairo, Egypt. While previous research has focused on one theory of safety design such as crime prevention, defensible space theory, eyes on the street or safer city centers, this article tries to fill in the gap in the literature by analyzing all aspects of urban design and its correlation to an enhanced perceived safety. In addition, most of the previous studies have tackled the safety aspects of old urban settlements. However, this study tackles a new urban settlement.
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Albert Lin, Cindy Kao and Heeju Park
This study aims to develop and evaluate a modular smart garment design framework that simplifies the technical content associated with smart garment design.
Abstract
Purpose
This study aims to develop and evaluate a modular smart garment design framework that simplifies the technical content associated with smart garment design.
Design/methodology/approach
Smart garment design challenges were first identified through literature review and interviews. Then, a modular framework and toolkit was created to address these challenges. Finally, workshops were held to evaluate the modular toolkit.
Findings
Interviews highlighted the need for easier attachment of hard devices to soft textile materials, simpler electrical connection creation and straightforward device selection. A modular framework was proposed and divided into four elements: (1) the Central Computation Module, (2) Peripheral Electrical Modules, (3) Securely Attaching Modules with Substrates and (4) Managing Intra-garment Connections. Workshops showed the modular framework had statistically significant improvements in function and certain ease ratings when compared to non-modular components.
Originality/value
This research identified specific technical challenges faced by smart garment designers and alleviated them through a modular smart garment framework that in workshops outperformed non-modular components in key function and ease ratings.
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Despite worldwide climate change and the problems caused by using fossil fuels, energy consumption in the world keeps rising every year. The areas with extremely cold or scorching…
Abstract
Purpose
Despite worldwide climate change and the problems caused by using fossil fuels, energy consumption in the world keeps rising every year. The areas with extremely cold or scorching climates are large, and significant amounts of energy are getting used in these areas for heating, cooling, and ventilation. The general purpose of this study is to investigate the possible relationship between the climatic characteristics of the Esfahak, a village located in the hot desert region of Iran, and the physical characteristics of its built environment.
Design/methodology/approach
The method of this research is qualitative and somewhat descriptive-analytical. In this regard, the architectural features of Esfahak village are compared with the principles mentioned in the Mahoney tables to determine the degree of compliance of the architecture of this village with the climatic condition.
Findings
The results show that design principles have been used in all indicators discussed in the Mahoney tables. By applying these principles, not only did the acute weather conditions not prevent the initial settlement in the village location, they have not caused inhabitants to leave the site over time as well.
Originality/value
The impacts of bioclimatic design strategies on thermal comfort in hot desert regions are seldom studied. This research provides evidence-based and informed design recommendations that can help building designers and city authorities integrate bioclimatic design strategies at the earliest conceptual design phases in hot desert climates.
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