Search results

This paper aims to study the mixed convective process due to various dynamics, namely, inner rotating cylinders and upper-wavy wall movement for the first time.

The Galerkin finite element method together with the characteristic-based split scheme is applied to solve the governing system.

The main outcomes revealed that the direction of the rotation of the cylinders, radius and locations of the rotating shapes are beneficial controlling elements for the enhancement of heat transfer. Also, for all the considered cases, values of the Bejan number indicate that the fluid friction irreversibility is dominance compared to the heat transfer irreversibility. Further, average values of the heat transfer entropy, fluid friction entropy and total entropy are minimized in the case of fixed cylinders regardless of the cylinder radius.

The authors are interested in the mixed convection case due to regular boundaries and hence this simulation purposes a first attempt to examine the mixed convective flow due to irregular wavy boundaries. This study considered various dynamics, namely, inner rotating cylinders and wavy-lid driven wall which makes it more attractive to the readers. Various cases based on radius of the cylinder and direction of the rotations together with several locations of the rotating shapes are taken into account which makes the current simulation is comprehensive. Various studies presented in this field are made by commercial software and these treatments need special conditions (having limitation) but the current solution methodology is based on a finite element method home-code. Various important impacts, are, also, examined, namely, inclined geometry, inclined magnetic field, thermal radiation and heat generation/absorption. The entropy of the current complex system is analyzed based on the second law of thermodynamics.

The purpose of this paper is to investigate the effects of magnetic field and viscous dissipation on mixed convection heat transfer, fluid flow and entropy generation in a porous media filled square enclosure heated with corner isothermal heater.

Finite volume method has been used to solve governing equations. A code is developed by FORTRAN and entropy generation is calculated from the obtained results of velocities and temperature. Results are presented via streamlines, isotherms, local and mean Nusselt number for different values of Richardson number (0.001=Ri=100), Hartmann number (0.001=Ha=100), Darcy number (0.001=Da=0.1), length of heaters (0.25=hx=hy=0.75) and viscous dissipation factors (10−4=ε=10−6).

It is observed that entropy is generated mostly due to lid-driven wall and right side of the heater. Entropy generation decreases with increasing of Hartmann number and heat transfer increases with decreasing of viscous parameter.

The originality of this work is to application of magnetic field and viscous dissipation on entropy generation in a lid-driven cavity with corner heater. Here, both corner heater and the external forces are original parameters.

The purpose of this numerical paper is to investigate the simulation of an unsteady double diffusive natural convection in square enclosure filled with a porous medium with various boundary conditions in the presence of thermal radiation and chemical reaction effects.

In this study, the governing dimensionless equations were written using the Brinkman Forchheimer extended Darcy model. They are numerically solved by using finite difference method by applying adiabatic boundary condition in top surface. The bottom surface is maintained at uniform temperature and concentration and left and right vertical walls are cooled.

Results are presented by streamlines, isotherms, temperature and concentration contours profiles as well as the local Nusselt number and Sherwood numbers for different values of the governing parameters such as Darcy number, buoyancy ratio, Rayleigh number, thermal radiation parameter and chemical reaction parameter. It is found that that both of the local Nusselt and Sherwood numbers increase as the Rayleigh number, buoyancy ratio and Darcy number increase. Moreover, increasing the thermal radiation effects leads to a pronounced increase in the local Nusselt number, while the opposite behavior is displayed by the local Sherwood number. Furthermore, the local Sherwood number increases and the local Nusselt number decrease when the chemical reaction parameter increase.

The originality of this study is the square cavity with various boundary conditions filled with a porous medium with thermal radiation and chemical reaction effects.

The purpose of this paper is to study the unsteady ferrofluid flow with a hot source helix inside a cavity under the impacts of a variable magnetic field by using the incompressible smoothed particle hydrodynamics method.

The governing equations are formulated by considering the basics of the magnetohydrodynamic and ferrohydrodynamics. Different locations of a variable magnetic source outside the geometry are investigated. The helical coils are extensively applied in the cooling and heating of air conditioners and heat pumps. Computations were carried out for different lengths of the heated helix (0.2 ≤ L_h ≤ 0.8), different locations of the magnetic source, (a = 0.5, b = −0.01), (a = 0.5, b = 1.01), (a = 1.01, b = 0.5), (a = −0.01, b = 0.5), different numbers of the inner helix (one helix, two helixes and three helixes) and different values of the nanoparticles volume fraction (0% ≤ ϕ ≤ 10%).

The outcomes of the investigations revealed that an increase in the lengths of a helix by 0.4 results in a reduction of the stream function by 25.60%. In addition, when the magnetic wire is located near the center of the right wall, the maximum values of the average Nusselt number are obtained while the smallest values of the average Nusselt number are given when the magnetic source is located near center of the top wall.

The novelty of this paper is investigating the natural convection flow from two different models of an inner hot helix inside a cavity with considering different locations of variable magnetic sources.

This paper aims to investigate the entropy generation due to magnetohydrodynamic natural convection flow and heat transfer in a porous enclosure filled with Cu-water nanofluid in the presence of viscous dissipation effect. The left and right walls of the cavity are thermally insulated. There are heated and cold parts, and these are placed on the bottom and top wall, respectively, whereas the remaining parts are thermally insulated.

The finite volume method is used to solve the dimensionless partial differential equations governing the problem. A comparison with previously published woks is presented and is found to be in an excellent agreement.

The minimization of entropy generation and local heat transfer according to different values of the governing parameters are presented in details. It is found that the presence of magnetic field has negative effects on the local entropy generation because of heat transfer and the local total entropy generation. Also, the increase in the heated part length leads to a decrease in the local Nusselt number.

This problem is original, as it has not been considered previously.

This paper aims to develop a lean manufacturing road map for industrial firms by selecting the appropriate lean tools relying on the predefined strategic objectives and the firm constraints. It also illustrates how to prioritize these tools considering their interrelationship.

Relying on the predefined strategic objectives, operational objectives can be set by using the balanced scorecard (BSC). Afterwards, the theory of constraints (TOC) is introduced to investigate the manufacturing system and to determine its constraints. For these constraints, the principle of fault tree analysis (FTA) is used to determine their root causes. Consequently, lean manufacturing tools/initiatives can be proposed. Finally, the fuzzy-decision making trial and evaluation laboratory (fuzzy-DEMATEL) method is implemented to prioritize these initiatives and to construct a suitable lean road map by managing experts’ knowledge.

The practical results indicate that diagnosing the manufacturing system and managing experts’ knowledge to select the appropriate lean initiatives, and prioritizing these initiatives relying on the understanding of their interrelationship could support achieving the strategic targets without consuming extra time or resources.

The study is limited to manufacturing firms. Besides, it reinforces the need for investigating the effectiveness of the proposed approach on service sectors.

The study provides a methodology with a real application, to manage experts’ knowledge for developing an effective lean improvement road map. The methodology could be adopted by any manufacturing firm.

The study supports decision makers of a firm to select the improvement initiatives by an original structural approach, which integrates BSC, TOC, FTA and fuzzy-DEMATEL. Besides, the interrelationships among the selected lean initiatives are considered, and results show the importance of analysing these interrelationships during the construction of the lean improvement plan. Moreover, its effectiveness and applicability are validated via a practical case study.

The Galerkin finite element method (FEM) based on the characteristic-based split (CBS) scheme is applied to simulate the nanofluid flow and thermal fields inside an inclined geometry filled by a heat-generating hydrodynamically and thermally anisotropic non-Darcy porous medium using the local thermal non-equilibrium model (LTNEM). Property of the hydrodynamic anisotropy is taken in both the Forchheimer coefficient and permeability and these tools are considered as functions of inclination of the principal axes. Also, the thermal conductivity for the porous phase is assumed to be anisotropic.

The Galerkin FEM based on the CBS scheme is applied to solve the partial differential equations governing the flow and thermal fields.

It is noted that the net rate of the heat transfer between the nanofluid and solid phases are influenced by variations of the anisotropic properties. Also, the system is reached to the thermal equilibrium state at H > 100. Further, the maximum nanofluid temperature is reduced by 12.27% when the nanoparticles volume fraction is varied from 0% to 4%.

This paper aims to study the nanofluid flow and heat transfer characteristics inside an inclined enclosure filled with a heat-generating, hydrodynamically and thermally anisotropic porous medium using the CBS scheme. The LTNEM is considered between the nanofluid and porous phases while the local thermal equilibrium model (LTEM) between the base fluid (water) and the nanoparticles (alumina) is taken into account. The Galerkin FEM is introduced to discretize the governing system of equations. Also, examine influences of the anisotropic properties (permeability, Forchheimer terms and thermal conductivity of the porous medium), inclination angle and nanoparticles volume fraction on the net rate of the heat transfer between the nanofluid and porous phases and on the local thermal non-equilibrium state is one of the concerns of this paper.

Achieving the goals of the sustainable development strategy and Egypt’s vision 2030 depends mainly on the existence of sources of funds. And since Egypt faces a great challenge in obtaining finance, then analyzing the drivers of financial development is a vital issue and there is a persistent need to shed light on the key obstacles for it. Thus, this paper aims to empirically assess the impact of natural resources, foreign direct investment (FDI) net inflows, education and clean energy sources on financial development in Egypt using the data of the 1971–2014 period.

The paper uses auto-regressive distributed lag and Toda-Yamomoto approaches to fulfill the purpose.

Empirical results signify that all variables except natural endowments stimulate financial development which can suggest the presence of the natural resources curse in Egypt. Moreover, the feedback effect between financial development and FDI is recognized. Clean energy sources cause financial development and natural endowments. Financial development causes natural endowments and FDI leads to the deployment of more clean energy resources.

Several crucial policy implications are suggested based upon these results as improving the quality and quantity of education and encouraging both domestic and foreign investors by providing several incentives. Moreover, the government has to enhance green finance through financing solar energy projects and other environmentally friendly projects.

It is the first research for Egypt that explores natural resource-financial development nexus using time series analysis according to our information, and two important variables are included in the model which is clean energy sources and FDI. Then, although several studies examined the impact of financial development on clean energy no empirical study before assessed the impact of clean energy on financial development.

The purpose of this study is to identify and assess new risks in construction projects that use 3D printing.

A mixed approach of both qualitative and quantitative methods was used. Literature review was conducted to extract 30 risks of 3D printing in construction. A survey was then developed to assess the probability and impact of these risks. In total, 37 respondents, who have experience and/or knowledge of 3D printing, completed the survey. The risk priority was calculated using a fuzzy logic approach. The main benefit of the proposed model is being able to use numerical and linguistic data in the risk assessment model.

The results show that the main risks, in terms of priority, are lack of codes and regulations for 3D printing in construction, delay in government approvals, shortage in labour skilled in 3D printed construction, lack of knowledge and information of 3D printed design concepts and changes in 3D construction codes and regulations.

This paper fills an identified gap in the literature related to 3D printing in construction and provides insights into the key risks affecting this disruptive technology.

The significance of organizational culture (OC) pervades all workplaces, extending even to health systems. While numerous studies have examined the perceptions of OC among nurses and physicians, there is a notable gap in understanding the perspectives of non-patient-facing health system employees. This study aims to fill this void by investigating the perceptions and drivers of OC among non-patient-facing personnel within health systems.

This study employed a mixed-methods approach, starting with a 31-question survey disseminated to health system employees through trade organizations to capture diverse perspectives on OC. Subsequently, employees were invited to participate in semi-structured interviews. A total of 23 interviews were conducted to explore the underlying factors shaping employees’ perceptions of OC.

A total of 67 surveys were completed, with 61 used in the analysis. The results revealed a predominantly positive outlook, highlighting the significance of supportive leadership and involvement in decision-making processes. The qualitative analysis identified four key themes: effective communication and transparency, coordinated teamwork, supportive leadership and the impact of external factors like the coronavirus disease 2019 (COVID-19) pandemic.

Effective leadership should prioritize open communication, employee autonomy and involvement in decision-making. These strategies foster a culture of trust, accountability and engagement, enhancing employee morale and job satisfaction while promoting a collaborative and innovative work environment conducive to long-term success and growth.

This research examines the often-overlooked perspectives of non-patient-facing health system staff, providing valuable insights and strategies for leaders to improve OC and create a more positive, inclusive and supportive work environment.