Journal of Simulation and Analysis of Novel Technologies in Mechanical Engineering
Volume:13 Issue: 3, Aug 2021

In this study, the electrochemical and hydrodynamic characteristics of a PEM fuel cell are investigated using an agglomerate model. Modeling is single-phase, two-dimensional, incompressible and steady-state. In this study, current density, water distribution and gas velocity inside the anode and cathode gas diffusion layers are obtained. This study using the present agglomerate model can provide a good prediction of the current density. The results show that the highest current density occurs in the areas of the interface between current collectors and gas diffusion layers. In addition, in the sharp areas, where the interface is between the current collectors and the gas diffusion layers, there is the highest flow velocity. In these areas, values of velocity gradients that can affect cell performance. Therefore, in order to achieve better performance, it is necessary to design different flow channels and gas diffusion layers and compare them with each other. The amount of water in the gas diffusion layer should be controlled so as not to reduce the chemical reaction on the cathode side.

In this study, CFD simulation of hydrothermal of a nanofluid in a microchannel under a magnetic field with spherical depressions and protrusions on hot and cold walls is investigated. The effects of increasing Hartman (Ha) and Reynolds numbers (Re) in various volume fraction (φ) are investigated. The governing equation by using single-phase model, finite volume method and SIMPLE algorithm are solved. Also it assumes the flow is laminar, steady-state and incompressible. The simulation are considered in ranges of 10 ≤ Re ≤150, 0 ≤ Ha ≤10, and 0 ≤ φ ≤0.03. The findings illustrate that in a certain Ha number, increasing in Re number and φ cause the Nu number increase. Also in a constant Re number, As the Ha number increases, the mean Nu number increases. Likewise, an increase in φ has enhanced heat transfer in all Re and Ha numbers. In a certain φ, as Ha number and Re number enhance, the Nu number increases. By enhancing thermal conductivity, the heat transfer increases. When Re=150, the percentage increase of heat transfer in φ=0.03 relative to pure fluid is %5.98.

Despite the spread of science in all fields in today's world, human beings are always seeking new knowledge. Energy is one of the issues that human beings significantly think about its control and protection. Solar chimneys can go through a very valuable process in hot and dry climates by creating air conditioning. Thus, the study of factors affecting the optimization of the solar chimney is inevitable. Since there is airflow in the solar chimney, it can be important to study the number of openings that cause air to enter the building in the wall of the building envelope. In this research was done using the simulated environment method in Design Builder software and the CFD analysis. Thus, a result of 25% was obtained by examining five sample openings with different percentages in the wall, which was the most suitable option for the model in terms of economic and energy efficiencies.

This work was intended as an attempt to motivate readers for a comparison study of constructions of Legendre multiwavelet and Chebyshev multiwavelet. It is also shown how to use them in Petrov-Galerkin approach for solving Fredholm integro-differential equation of high orders of the second kind. In fact, a numerical technique for the discretization method of Fredholm integro-differential equations is presented that yields linear system. The important point to note here is the convergence of presented methods. For the first time, two conditions are proved for convergence of Legendre and Chebyshev multiwavelets in Petrov-Galerkin method. The proof of these conditions with using linear algebra and matrix theory ensures that Petrov-Galerkin methods has a unique approximation. Finally, some relevent numerical examples, for which the exact solution is known, will indicate accuracy and applicability of the proposed method.

Today, electronic ceramics make up the largest share of advanced markets. Ceramics are chemically neutral and resistant to high temperatures, so they provide a good environment for circuits. Most ceramics have electronic mobility. Ceramic engineering is one of the attractive trends in the field of materials science and engineering. In ceramic engineering, parts are made of inorganic and non-metallic materials. Like other trends in materials engineering, ceramic engineering is based on the study of the structure, chemical composition and properties of ceramic materials from the atomic dimension of the material to its bulk structure. Ceramic materials have different crystalline, semi-crystalline and amorphous structures. In other classifications, ceramics are divided into two categories such as traditional and advanced ceramics. Therefore, in this we evaluate the mechanical properties and application of the modern ceramics. Nowadays, the study of engineered and advanced ceramics is very widespread. Advanced ceramics are a group of ceramics that have components, complex manufacturing technology and more sensitive applications, and different categories are considered for them in which are in the form of engineering ceramics, glass ceramics, electro ceramics and bioceramics.

Alginate is a natural polysaccharide that is extracted from alga sources mainly laminaria. Alginate is readily processable for applicable three-dimensional (3D) scaffold materials such as hydrogels, microspheres, microcapsules, sponges, foams and fibers. Alginate hydrogels have been particularly attractive in wound healing, drug delivery, neuroscience and soft tissue engineering applications. As these gels retain structural similarity to the extracellular matrices (ECM) in tissues and can be manipulated to play several critical roles. The nervous system is a crucial component of the body and damages to this system, either by of injury or disease which can result in serious or potentially lethal consequences. In this research, the aim is to simulate nerve fibers in Abaqus simulation software by finite element method (FEM). Also, the use of a similar material such as alginate can be used to validate this simulation. Restoring the damaged nervous system is a great challenge due to the complex physiology system and limited regenerative capacity. Currently, most of neural tissue engineering applications are in pre-clinical study, in particular for use in the central nervous system, however collagen polymer conduits aimed at regeneration of peripheral nerves have already been successfully tested in clinical trials. In this study, due to the complexity of measuring nerve endurance, static simulation was used in Abaqus software and the results showed that paired strings are stronger than the number of individuals and the string plays a key role in the center.