Articleshttp://hdl.handle.net/20.500.14131/5472024-03-28T12:58:52Z2024-03-28T12:58:52ZFates of a Nonwetting Slug in Tapered Microcapillaries under Gravity and Zero Gravity Conditions: Dynamics, Asymptotic Equilibrium Analysis, and Computational Fluid Dynamics VerificationsAmgad SalamaJisheng KouEl-Amin, Mohamed F.http://hdl.handle.net/20.500.14131/14632024-02-28T05:57:56Z2024-02-21T00:00:00ZFates of a Nonwetting Slug in Tapered Microcapillaries under Gravity and Zero Gravity Conditions: Dynamics, Asymptotic Equilibrium Analysis, and Computational Fluid Dynamics Verifications
Amgad Salama; Jisheng Kou; El-Amin, Mohamed F.
It has been determined experimentally and numerically that a nonwetting slug in a tapered capillary tube, under the sole action of capillary force, self-propels itself toward the wider end of the tube until an equilibrium state is reached. The aim of this work is to highlight the state of the slug at equilibrium in terms of configuration and location. Furthermore, it turns out that gravity adds richness to this phenomenon, and more fates become possible. A modified Bond number is developed that determines the relative importance of gravity and capillarity for this system. According to the magnitude of the Bond number, three more fates are possible. Therefore, in a tapered capillary tube held vertically upward with its wider end at the top, in the absence of gravity or under microgravity conditions, the nonwetting slug moves upward toward the wider end of the tube until it reaches equilibrium with the two menisci part of a single sphere. The location of the slug at equilibrium in this case represents the farthest fate among the other fates. When gravity exists yet capillarity dominates, the slug still moves upward toward the wider end. However, in this case, the two menisci become parts of two different spheres of different curvatures. For this scenario, the slug climbs upward but reaches a lower level compared to the previous scenario. On the other hand, when gravity dominates, the slug experiences a net downward pull toward the narrower end of the tube and starts to move in the direction of gravity until capillary force establishes a balance, then it stops. When gravity sufficiently dominates, it pulls the slug downward until it completely drains off the tube. A computational fluid dynamics (CFD) analysis is conducted in order to build a framework for verification exercises. Excellent agreements between the results of the developed model and the CFD analysis are obtained. A fate map and a scheme are developed to identify these four fates based on two Bond numbers; namely, the initial Bond number and that associated with the slug when it is at the exit.
2024-02-21T00:00:00ZMapping the Research Landscape of Organizational Climate and Performance Using Bibliometric AnalysisSif Islem AmalouBrahimi, Tayebhttp://hdl.handle.net/20.500.14131/14622024-02-28T05:55:28Z2023-12-01T00:00:00ZMapping the Research Landscape of Organizational Climate and Performance Using Bibliometric Analysis
Sif Islem Amalou; Brahimi, Tayeb
This study aims to address the limited understanding of rganizational climate and performance by conducting a omprehensive bibliometric analysis of scholarly publications. The methodology involves analyzing publications using bibliometric techniques and VOSviewer. The results indicate that organizational performance, employee engagement, job satisfaction, leadership, and leadership culture are prominent topics within the field. The top five countries in terms of published documents and citations are the USA, India, the UK, Australia, and Malaysia. Recent publications have prioritized topics such as quality of work life, innovation, productivity, well-being, organizational commitment, work engagement, and corporate social responsibility. This study provides valuable insights for researchers, practitioners, and organizations to improve employee performance and productivity. The significance of this work lies in its ability to inform future research directions and guide collaboration efforts. Ultimately, this study advances the understanding of organizational climate and performance with practical implications for various organizational settings.
2023-12-01T00:00:00ZAnalytical solutions for harvesting atmospheric water using desiccant materialsEl-Amin, Mohamed F.http://hdl.handle.net/20.500.14131/14452024-02-27T12:02:06Z2023-09-21T00:00:00ZAnalytical solutions for harvesting atmospheric water using desiccant materials
El-Amin, Mohamed F.
Atmospheric water generation using desiccant materials is a promising technology for producing clean drinking water in water-scarce regions. While experimental research on this topic has been extensive, modeling and simulation research are still in their nascent stages. The development of accurate models and simulations is crucial for predicting performance and refining system design. This paper presents analytical solutions for predicting and improving the behavior of water absorption and desorption by the calcium chloride (CaCl2) desiccant, which is commonly used in atmospheric water generation systems. The model considers several physical effects, such as mass transfer, and diffusion. The model considers a linear relationship between the collected water content and relative humidity. Based on this assumption the model has been solved analytically for different cases of boundary conditions including, Dirichlet boundary conditions and Dirichlet–Neumann boundary conditions. Several physical scenarios have been calculated and the results have been discussed.
2023-09-21T00:00:00ZAnalytical solutions for harvesting atmospheric water using desiccant materialsEl-Amin, Mohamed F.http://hdl.handle.net/20.500.14131/10642023-10-01T09:46:04Z2023-09-21T00:00:00ZAnalytical solutions for harvesting atmospheric water using desiccant materials
El-Amin, Mohamed F.
Atmospheric water generation using desiccant materials is a promising technology for producing clean drinking water in water-scarce regions. While experimental research on this topic has been extensive, modeling and simulation research are still in their nascent stages. The development of accurate models and simulations is crucial for predicting performance and refining system design. This paper presents analytical solutions for predicting and improving the behavior of water absorption and desorption by the calcium chloride (CaCl2) desiccant, which is commonly used in atmospheric water generation systems. The model considers several physical effects, such as mass transfer, and diffusion. The model considers a linear relationship between the collected water content and relative humidity. Based on this assumption the model has been solved analytically for different cases of boundary conditions including, Dirichlet boundary conditions and Dirichlet–Neumann boundary conditions. Several physical scenarios have been calculated and the results have been discussed.
2023-09-21T00:00:00Z