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The purpose of this paper is to consider natural convection of a nanofluid inside of a C-shaped cavity using Lattice Boltzmann method (LBM).

Effects of some geometry and flow parameters consisting of the aspect ratio of the cavity, aspect ratio of the heat source; Rayleigh number (Ra = 10³ − 10⁶) have been investigated. The validity of the method is checked by comparing the present results with ones from the previously published work.

The results demonstrate that for Ra = 10³, the aspect ratio of the heat source has more influence on the average Nusselt number in contrast to the case of Ra = 10⁶. Contrary to the fact that the average Nusselt number increases non-linearly more than twice because of the increase of the aspect ratio of the enclosure at Ra = 10³, the average Nusselt number has a linear relation with the aspect ratio for of Ra = 10⁶. Therefore, upon increasing the Rayleigh number, the efficiency of the aspect ratio of the cavity on the thermal convection, gradually diminishes.

The authors believe that all the results, both numerical and asymptotic, are original and have not been published elsewhere.

This paper aims to numerically investigate the natural convection heat transfer of a hybrid nanofluid into a porous cavity exposed to a variable magnetic field.

The non-linear elliptical governing equations have been solved numerically using control volume based finite element method. The effects of different governing parameters including Rayleigh number (Ra = 10³ − 10⁶), Hartman number (Ha = 0 − 50), volume fraction of nanoparticles (φ = 0 − 0.02), curvature of horizontal isolated wall (a = 0.85 − 1.15), porosity coefficient (ε = 0.1 − 0.9) and Darcy number (Da = 10⁻⁵ − 10⁻¹) have been studied.

The results indicate that at low Darcy numbers close to 0, the average Nusselt number Nu_a enhances as porosity coefficient increases. For a = 1 and a = 1.15 in comparison with a = 0.85, the stretching of the isothermal lines is maintained from the left side to the right side and vice versa, which indicates increased natural convection heat transfer for this configuration of the top and bottom walls. In addition, at higher Rayleigh numbers, by increasing the Hartmann number, a significant decrease is observed in the Nusselt number, which can be attributed to the decreased power of the flow.

The authors believe that all the results, both numerical and asymptotic, are original and have not been published elsewhere.

This study aims to use the thermal non-equilibrium approach to inquire the entropy production and conjugate natural heat exchange in a porous medium. Entropy generation is studied separately for the solid matrix and the hybrid nanoliquid.

The characteristic equations are unraveled by applying the finite element method. Mathematical relations are used to calculate the generated entropy for the hybrid nanoliquid and matrix structure.

Based on the results, the produced entropy and the viscous friction term associated with the hybrid nanoliquid phase are not affected by increasing the thermal conductivity ratio of the rigid wall to nanoliquid. Moreover, a higher amount of entropy is generated by the thermal gradients in the hybrid nanoliquid phase compared to the solid matrix.

No investigation in the literature has been reported in this context.

This study aims to evaluate the melting process of the phase-change RT-35 material in a shell and tube heat exchanger saturated with a porous medium. Titanium porous media with isotropic and inhomogeneous structures are studied. The considered tubes in the shell and tube exchanger are made of copper with specific thicknesses. The phase-change material has a non-Newtonian behavior and follows the endorsed Carreau–Yasuda Model.

The enthalpy–porosity method is used for modeling of the melting process. The governing equations were transferred to their dimensionless forms. Finally, the equations are solved by applying the Galerkin finite element method.

The findings for different values of the relative permeability (K*) and permeability deviation angle (λ) are represented in the forms of charts, streamlines and constant temperature contours. The considerable effects of the relative permeability (K*) and deviation angle (λ) on the flow line patterns of the melting phase-change material are some of the significant achievements of this works.

This study was conducted using data from relevant research articles provided by reputable academic sources. The data included in this manuscript have not been published previously and are not under consideration by any other journal.

This paper aims to study the natural convection of a nanofluid inside a cavity which contains obstacles using lattice Boltzmann method (LBM). The results have focused mainly on various parameters such as number and aspect ratio of roughness elements and different nanoparticle volume fraction. The isotherms and streamlines are presented to describe the hydrodynamics and thermal behaviors of the nanofluid flow throughout the enclosure.

The methodology of this paper consists of mathematical model, statement of the problem, nanofluid thermophysical properties, lattice Boltzmann method, LBM for fluid flow, LBM for heat transfer, numerical strategy, boundary conditions, Nusselt (Nu) number calculation, code validation and grid independence.

Natural convection heat transfers of a nanofluid inside cavities with and without rough elements have been studied. Lattice Boltzmann technique has been used as numerical approach. The results showed that at higher Rayleigh number (Ra = 10⁶), there are denser streamlines near the left (source) and right wall (sink) which results in better cooling and enhances convective heat rejection to the heat sink. After a distinctive aspect ratio of rough elements (A = 0.1), change in streamline pattern which arises from increasing of aspect ratio does not have an important effect on isotherms. Results indicate that for lower Rayleigh number (Ra = 10³), no variation in average Nu is observed with increasing in number of roughness, while for higher one (Ra = 10⁶) average Nu decreases from N = 0 (smooth cavity) up to N = 4 and then remains constant (N = 6).

Currently, no argumentative and comprehensive extraction can be concluded without fully understanding the role of different arrangement of roughness. Some geometrical parameters such as aspect ratio, number and position of rough elements have been considered. Also, the effect of nanoparticle concentration was studied at different Ra number. Briefly, using LBM, this paper aims to investigate the natural convection of a nanofluid flow on the thermal and hydrodynamics parameters in the presence of rough element with various arrangements.

The purpose of this paper is to numerically study MHD natural convection and entropy generation of Al₂O₃-water alumina nanofluid inside of T-shaped baffled cavity which is subjected to a magnetic field.

Effect of various geometrical, fluid and flow factors such as aspect ratio of enclosure and baffle length, Rayleigh and Hartmann number of nanofluid have been considered in detail. The hydrodynamics and thermal indexes of nanofluid have been described using streamlines, isotherms and isentropic lines.

It is found that by enhancing Hartmann number, symmetrical streamlines gradually lose symmetry and their values decline. It is found that by enhancing Hartmann number, symmetrical streamlines gradually lose symmetry and their values decline. The interesting finding is an increase in the impact of Hartmann number on heat transfer indexes with augmenting Rayleigh number. However, with augmenting Rayleigh number and, thus, strengthening the buoyant forces, the efficacy of Hartmann number one, an index indicating the simultaneous impact of natural heat transfer to entropy generation increases. It is clearly seen that the efficacy of nanofluid on increased Nusselt number enhances with increasing aspect ratio of the enclosure. Based on the results, the Nusselt number generally enhances with the larger baffle length in the enclosure. Finally, with larger Hartmann number and lesser Nusselt one, entropy production is reduced.

The authors believe that all the results, both numerical and asymptotic, are original and have not been published elsewhere.

This study aims to investigate the insights of soot formation such as rate of soot coagulation, rate of soot nucleation, rate of soot surface growth and soot surface oxidation in ethylene/hydrogen/nitrogen diffusion jet flame at standard atmospheric conditions, which is very challenging to capture even with highly sophisticated measuring systems such as Laser Induced Incandescence and Planar laser-induced fluorescence. The study also aims to investigate the volume of soot in the flame using soot volume fraction and to understand the global correlation effect in the formation of soot in ethylene/hydrogen/nitrogen diffusion jet flame.

A large eddy simulation (LES) was performed using box filtered subgrid-scale tensor. A filtered and residual component of the governing equations such as continuity, momentum, energy and species are resolved and modeled, respectively. All the filtered and residual components are numerically solved using the ILU method by considering PISO pressure–velocity solver. All the hyperbolic flux uses the QUICK algorithm, and an elliptic flux uses SOU to evaluate face values. In all the cases, Courant–Friedrichs–Lewy (CFL) conditions are maintained unity.

The findings are as follows: soot volume fraction (SVF) as a function of a flame-normalized length for three different Reynolds number configurations (Re = 15,000, Re = 8,000 and Re = 5,000) using LES; soot gas phase and particulate phase insights such as rate of soot nucleation, rate of soot coagulation, rate of soot surface growth and soot surface oxidation for three different Reynolds number configurations (Re = 15,000, Re = 8,000 and Re = 5,000); and soot global correction using total soot volume in the flame volume as a function of Reynolds number and Froude number.

The originality of this study includes the following: coupling LES turbulent model with chemical equilibrium diffusion combustion conjunction with semi-empirical Brookes Moss Hall (BMH) soot model by choosing C6H6 as a soot precursor kinetic pathway; insights of soot formations such as rate of soot nucleation, soot coagulation rate, soot surface growth rate and soot oxidation rate for ethylene/hydrogen/nitrogen co-flow flame; and SVF and its insights study for three inlet fuel port configurations having the three different Reynolds number (Re = 15,000, Re = 8,000 and Re = 5,000).

This paper aims to examine the mediating role of big data adoption (BDA) on the association between board governance (BG) and audit report lag (ARL).

This study uses data extracted from financial reports for a sample from EGX100 over the period from 2015 to 2019. This study applies content analysis approach to measure the level of BDA. This study uses ordinary least squares, structure equation modelling and principal component analysis to investigate the relationship between BG, BDA and ARL.

The findings indicate that BDA can be used as a predictor of ARL for companies listed on the Egyptian stock exchange. The results show that board diversity has a significant effect on ARL when BDA is used as a mediator.

This study only includes technology, telecommunications and health-care industries in the sample.

This paper raises investor and stakeholder awareness for the importance of BDA and corporate governance (CG) procedures in reducing audit report delays in developing countries such as Egypt. This study can assist regulators in developing audit report requirements and enforcing regulations to guarantee timely audit report publication.

This paper provides a shred of unique evidence on the role of BDA in mediating the relationship between BG and ARL in a developing country.

The government sometimes lacks sufficient financial, management and technical capabilities to deliver construction projects. As a result, it has recognized the need to introduce private sector capital and expertise to complete unfinished construction projects. This outsourcing paradigm is known as a public-private partnership, a form of privatization. This study aims to identify the barriers associated with the transfer of unfinished construction projects to the private sector in Iran and grouped them into areas that were ranked to shed light on where the risk lies.

After a thorough and comprehensive literature review, a questionnaire was developed and distributed to 67 experts in the public and private sectors in Iran. The survey included 37 barriers grouped into seven areas and measured on a five-point Likert scale. Face validity, content validity and structural validity of the collected data were confirmed. The reliability of the questionnaire was also tested and validated using Cronbach’s alpha coefficient.

The survey findings indicated that private company laws, national constitution, government policies, lack of sufficient regulations, one-sided regulations and lack of balance, the regulations of other organizations and taxation laws were perceived as the major barriers to the transfer of unfinished public sector construction projects to the private sector in Iran. The ranking of the seven areas produced the following top three ranked barriers areas: taxation laws, government policies and one-sided regulations and lack of balance of importance.

The elicitation of this study can be useful to both private and public sectors for the development of infrastructure construction projects.