T. Javed, Z. Mehmood and Ioan Pop
The purpose of this paper is to analyze numerical results for heat transfer through mixed convection in an incompressible steady lid-driven fluid flow inside a trapezoidal cavity…
Abstract
Purpose
The purpose of this paper is to analyze numerical results for heat transfer through mixed convection in an incompressible steady lid-driven fluid flow inside a trapezoidal cavity in the presence of a uniform magnetic field.
Design/methodology/approach
In this study, the authors have considered three different cases, in which left and right walls of the cavity are tilted at different angles of 0, 30 and 45 degrees, respectively. Both left and right side walls of the cavity are taken cold and the upper wall is insulated and assumed moving with constant speed, whereas the bottom wall is considered to be heated uniformly/non-uniformly. To eliminate pressure term, penalty method is applied to governing Navier–Stokes’ equations. The reduced equations are solved by Galerkin weighted residual technique of finite element method. Grid-independent results are obtained and shown in terms of plots for streamlines, isotherms, Nusselt number and average Nusselt number for a wide range of flow parameters, including Rayleigh numbers Ra, Prandtl number Pr and Hartman number Ha.
Findings
It has been observed that the effects of moving lid become negligible for Ra = 100,000, whereas increasing Rayleigh number results in stronger streamline circulation and convection dominant effects inside the enclosure. Local Nusselt number Nu along the bottom wall is observed to be maximum at edges and it reduces while moving toward the center from edges, and attains minimum value at the center of the bottom wall.
Research limitations/implications
The problem is modeled for laminar and incompressible flow, induced magnetic field has been considered negligibly small and local thermal equilibrium has been assumed.
Originality/value
In this investigation, the authors have presented new and original results for mixed convection flow inside a lid-driven trapezoidal cavity under the influence of a magnetic field. Hence, this study would be important for the researchers working in the area of heat transfer in cavity flows involving magnetic effects to become familiar with the flow behavior and properties.
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T. Javed, Z. Mehmood, M.A. Siddiqui and Ioan Pop
The purpose of this paper is to perform a numerical study for heat transfer through natural convection in the presence of a constant magnetic field in an incompressible steady…
Abstract
Purpose
The purpose of this paper is to perform a numerical study for heat transfer through natural convection in the presence of a constant magnetic field in an incompressible steady nanofluid flow inside an isosceles triangular cavity.
Design/methodology/approach
For this flow problem, the left wall of the cavity subjected to uniform/nonuniform heat was considered, while right and bottom walls of the cavity were kept cold. The obtained equations were solved by using the Galerkin weighted residual technique. Results are computed for a wide range of parameters including Rayleigh number (Ra) (10^3 < Ra < 10^7), Hartman number (Ha) (0 < Ha < 60), and heat-generation/-absorption coefficient (q) (−10 < q < 10), while, Prandtl number (Pr) was kept fixed at 6.2. These computed results are presented in terms of stream functions, isotherms, Nusselt numbers and average Nusselt numbers through figures.
Findings
It is observed that, in case of uniform heating of the side wall, the strength of stream lines’ circulations increases with an increase in Ra and decreases with an increase in Ha. Similarly, by increasing heat-absorption coefficient q, an increase in the circulation strength is noted and the circulation cell moves towards the left wall in the presence of a heat sink (q < 0) and moves to the cold right wall in the presence of a heat source (q > 0). In the case of nonuniformly heated left wall in the presence of a heat source (q > 0), a higher-temperature gradient is observed in the cavity and isotherms are clustered to the left wall in the lower portion and to right wall in the upper portion; these appear to be straight and parallel to the x-axis near the bottom wall. On the other hand, the heat transfer rate along all the walls of the cavity is observed to be higher for smaller values of q. Whereas, Nusselt number along the bottom wall (Nu-B) increases with an increase in the values of x, while, that along the left wall (Nu-L) first increases and then decreases. But Nusselt number along the right wall (Nu-R) is found to be qualitatively opposite to Nu-L with an increase in distance x. Whereas, average Nusselt number increases with an increase in Rayleigh number Ra and heat-generation/-absorption coefficient q.
Research limitations/implications
The problem is formulated for an incompressible flow; viscous dissipation has been neglected, negligible induced magnetic field has been considered and local thermal equilibrium has been considered.
Originality/value
Results presented in this paper are original and new for the effects of a uniform magnetic field on the natural convection of Cu–water nanofluid in a triangular cavity. Hence, this study is important for researchers working in the area of heat transfer in cavity flows involving the nanofluid to become familiar with the flow behavior and properties.
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Madiha Ajmal, Rashid Mehmood, Noreen Sher Akbar and Taseer Muhammad
This study aims to focuse on the flow behavior of a specific nanofluid composed of blood-based iron oxide nanoparticles, combined with motile gyrotactic microorganisms, in a…
Abstract
Purpose
This study aims to focuse on the flow behavior of a specific nanofluid composed of blood-based iron oxide nanoparticles, combined with motile gyrotactic microorganisms, in a ciliated channel with electroosmosis.
Design/methodology/approach
This study applies a powerful mathematical model to examine the combined impacts of bio convection and electrokinetic forces on nanofluid flow. The presence of cilia, which are described as wave-like motions on the channel walls, promotes fluid propulsion, which improves mixing and mass transport. The velocity and dispersion of nanoparticles and microbes are modified by the inclusion of electroosmosis, which is stimulated by an applied electric field. This adds a significant level of complexity.
Findings
To ascertain their impact on flow characteristics, important factors such as bio convection Rayleigh number, Grashoff number, Peclet number and Lewis number are varied. The results demonstrate that while the gyrotactic activity of microorganisms contributes to the stability and homogeneity of the nanofluid distribution, electroosmotic forces significantly enhance fluid mixing and nanoparticle dispersion. This thorough study clarifies how to take advantage of electroosmosis and bio convection in ciliated micro channels to optimize nanofluid-based biomedical applications, such as targeted drug administration and improved diagnostic processes.
Originality/value
First paper discussed “Numerical Computation of Cilia Transport of Prandtl Nanofluid (Blood-Fe3O4) Enhancing Convective Heat Transfer along Micro Organisms under Electroosmotic effects in Wavy Capillaries”.
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Sawan Kumar Rawat, Ashish Mishra and Manoj Kumar
The purpose of this paper is to explore the flow of Cu-water and Ag-water nanofluids past a vertical Riga plate. The plate is infinite in height and has zero normal wall flux…
Abstract
Purpose
The purpose of this paper is to explore the flow of Cu-water and Ag-water nanofluids past a vertical Riga plate. The plate is infinite in height and has zero normal wall flux through its surface. Influence of thermal radiation, slip, suction and chemical reaction on the flow characteristics are reported.
Design/methodology/approach
Non-dimensional forms of the flow governing equations are obtained by means of a set of similarity transformations. Numerical solution is obtained with the help of fourth-fifth-order Runge–Kutta–Fehlberg method with shooting procedure. Comparison of solution profiles of Cu-water and Ag-water nanofluids are presented graphically and with the help of tables. Influence of pertinent parameters on skin friction and heat transfer rate is also reported.
Findings
Results reveal that the skin friction coefficient is more prominent in the case of Ag-water nanofluid for an increase in thermal radiation and volume fraction. The role of suction and slip is to increase velocity but decrease the temperature in both nanofluids. Temperature and velocity of both nanofluids increase as volume fraction and thermal radiation values are augmented. Heat transport increases with thermal radiation. Region near the plate experiences rise in nanoparticle concentration with an increase in chemical reaction parameter.
Originality/value
A complete investigation of the modeled problem is addressed and the results of this paper are original.
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Muhammad Sohail and Sana Tariq
Thermal and species transport of magneto hydrodynamic Casson liquid over a stretched surface is investigated theoretically in this examination for the three-dimensional boundary…
Abstract
Purpose
Thermal and species transport of magneto hydrodynamic Casson liquid over a stretched surface is investigated theoretically in this examination for the three-dimensional boundary layer flow of a yield exhibiting material. The phenomenon of heat and species relocation is based upon modified Fourier and Fick’s laws that involves the relaxation times for the transportation of heat and mass. Conservation laws are modeled under boundary layer analysis in the Cartesian coordinates system. The purpose of this paper is to find the influence of different emerging parameters on fluid velocity, temperature and transport of species.
Design/methodology/approach
Reconstructed nonlinear boundary layer ordinary differential equations are analyzed through eigenvalues and eigenvectors. Due to the complexity and non-existence of the exact solution of the transformed equations, a convergent series solution by the homotopy algorithm is also derived. The reliability of the applied scheme is presented by comparing the obtained results with the previous findings.
Findings
Physical quantities of interest are displayed through graphs and tables and discussed for sundry variables. It is discerned that higher magnetic influence slows down fluid motion, whereas concentration and temperature profiles upsurge. Reliability of the recommended scheme is monitored by comparing the obtained results for the dimensionless stress as a limiting case of previous findings and an excellent agreement is observed. Higher values of Schmidt number reduce the concentration profile, whereas mounting the values of Prandtl number reduces the dimensionless temperature field. Moreover, heat and species transfer rates increase by mounting the values of thermal and concentration relaxation times.
Originality/value
The phenomenon of heat and species relocation is based upon modified Fourier and Fick’s laws which involves the relaxation times for the transportation of heat and mass. Conservation laws are modeled under boundary layer analysis in the Cartesian coordinates system.
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Irfan Ahmed, Owais Mehmood, Zeshan Ghafoor, Syed Hassan Jamil and Afkar Majeed
This study aims to examine the impact of board characteristics on debt choice.
Abstract
Purpose
This study aims to examine the impact of board characteristics on debt choice.
Design/methodology/approach
The sample comprises of unique nonfinancial firms listed in the FTSE 350 over the period 2011–2018. This study uses Tobit and OLS regressions to check the impact of board characteristics on debt choice. The results are robust to the battery of robust checks.
Findings
This study finds that board size and board independence are positively associated with public debt. However, CEO duality and board meetings frequency are inversely associated with public debt. Overall, the findings are consistent with the “financial intermediation theory” that the firms with weak governance rely on bank financing, and firms with better corporate governance go for public debt.
Research limitations/implications
This study offers significant insights for investors and policymakers.
Originality/value
This study offers new insights regarding the role of board characteristics in firms’ debt choice by showing the significant impact of board characteristics on debt choice. The findings indicate that the board’s efficient internal monitoring may substitute external monitoring by the bank.
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Rashid Mehmood, Royston Meriton, Gary Graham, Patrick Hennelly and Mukesh Kumar
The purpose of this paper is to advance knowledge of the transformative potential of big data on city-based transport models. The central question guiding this paper is: how could…
Abstract
Purpose
The purpose of this paper is to advance knowledge of the transformative potential of big data on city-based transport models. The central question guiding this paper is: how could big data transform smart city transport operations? In answering this question the authors present initial results from a Markov study. However the authors also suggest caution in the transformation potential of big data and highlight the risks of city and organizational adoption. A theoretical framework is presented together with an associated scenario which guides the development of a Markov model.
Design/methodology/approach
A model with several scenarios is developed to explore a theoretical framework focussed on matching the transport demands (of people and freight mobility) with city transport service provision using big data. This model was designed to illustrate how sharing transport load (and capacity) in a smart city can improve efficiencies in meeting demand for city services.
Findings
This modelling study is an initial preliminary stage of the investigation in how big data could be used to redefine and enable new operational models. The study provides new understanding about load sharing and optimization in a smart city context. Basically the authors demonstrate how big data could be used to improve transport efficiency and lower externalities in a smart city. Further how improvement could take place by having a car free city environment, autonomous vehicles and shared resource capacity among providers.
Research limitations/implications
The research relied on a Markov model and the numerical solution of its steady state probabilities vector to illustrate the transformation of transport operations management (OM) in the future city context. More in depth analysis and more discrete modelling are clearly needed to assist in the implementation of big data initiatives and facilitate new innovations in OM. The work complements and extends that of Setia and Patel (2013), who theoretically link together information system design to operation absorptive capacity capabilities.
Practical implications
The study implies that transport operations would actually need to be re-organized so as to deal with lowering CO2 footprint. The logistic aspects could be seen as a move from individual firms optimizing their own transportation supply to a shared collaborative load and resourced system. Such ideas are radical changes driven by, or leading to more decentralized rather than having centralized transport solutions (Caplice, 2013).
Social implications
The growth of cities and urban areas in the twenty-first century has put more pressure on resources and conditions of urban life. This paper is an initial first step in building theory, knowledge and critical understanding of the social implications being posed by the growth in cities and the role that big data and smart cities could play in developing a resilient and sustainable transport city system.
Originality/value
Despite the importance of OM to big data implementation, for both practitioners and researchers, we have yet to see a systematic analysis of its implementation and its absorptive capacity contribution to building capabilities, at either city system or organizational levels. As such the Markov model makes a preliminary contribution to the literature integrating big data capabilities with OM capabilities and the resulting improvements in system absorptive capacity.
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Aurang Zaib, Rizwan Ul Haq, Ali J. Chamkha and Mohammad Mehdi Rashidi
The purpose of this paper is to present an inclusive study of the mixed convective flow involving micropolar fluid holding kerosene/water-based TiO2 nanoparticle towards a…
Abstract
Purpose
The purpose of this paper is to present an inclusive study of the mixed convective flow involving micropolar fluid holding kerosene/water-based TiO2 nanoparticle towards a vertical Riga surface with partial slip. The outcomes are confined for opposing and assisting flows.
Design/methodology/approach
Similarity equations are acquired and then worked out numerically by the Keller box technique.
Findings
Impacts of significant parameters on microrotation velocity, temperature distribution, velocity profile together with the Nusselt number and the skin friction are argued with the help of graphs. Two solutions are achieved in opposing flow, while the solution is unique in assisting flow. It is also monitored that the separation of boundary layer delays because of micropolar parameter and accelerates because of volume fraction.
Originality/value
The authors trust that all these results are new and significant for researchers.
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Olumide Falodun Bidemi and M.S. Sami Ahamed
The purpose of this paper is to consider a two-dimensional unsteady Casson magneto-nanfluid flow over an inclined plate embedded in a porous medium. The novelty of the present…
Abstract
Purpose
The purpose of this paper is to consider a two-dimensional unsteady Casson magneto-nanfluid flow over an inclined plate embedded in a porous medium. The novelty of the present study is to investigate the effects of Soret–Dufour on unsteady magneto-nanofluid flow.
Design/methodology/approach
Appropriate similarity transformations are used to convert the governing non-linear partial differential equations into coupled non-linear dimensionless partial differential equations. The transformed equations are then solved using spectral relaxation method.
Findings
The effects of controlling parameters on flow profiles is discussed and depicted with the aid of graphs. Results show that as the non-Newtonian Casson nanofluid parameter increases, the fluid velocity decreases. It is found that the Soret parameter enhance the temperature profile, while Dufour parameter decreases the concentration profile close to the wall.
Originality/value
The novelty of this paper is to consider the combined effects of both Soret and Dufour on unsteady Casson magneto-nanofluid flow. The present model is in an inclined plate embedded in a porous medium which to the best of our knowledge has not been considered in the past. The applied magnetic field gives rise to an opposing force which slows the motion of the fluid. A newly developed spectral method known as spectral relaxation method (SRM) is used in solving the modeled equations. SRM is an iterative method that employ the Gauss–Seidel approach in solving both linear and non-linear differential equations. SRM is found to be effective and accurate.