Reverse Osmosis is one of the membrane processes used to desalinate salt water, remove natural organic compounds, certain contaminants and water softening. One of the most important problems with this type of membrane is the polarization of the concentration and deposition in them, which reduces the product flux and increases the passage of salt through the membrane and also increases the pressure drop. It is important to choose the proper type of membrane to meet the needs associated with the Reverse Osmosis separation process. In this study, Polydioxanone polymer (12%) was used to make the Reverse Osmosis membrane. Also, the phenomenon of mass transfer in the Reverse Osmosis condensation process of the mathematical model based on the separation of water-glucose solution was considered. Considering the surface structure of the membrane, the irreversible thermodynamic model of Spiegler-Kedem was selected to investigate the mass transfer inside the membrane, and the concentration polarization model was assumed to be one-dimensional flow to investigate the mass transfer outside the membrane. The current is assumed to be constant and compressible with constant properties. The results of this study show a decrease in the amount of pure water flux along the membrane due to accumulation of salts and pressure drop and increase in the width of the membrane with increasing pressure and feed concentration. The results obtained from the distribution of glucose concentration in the water show that increasing the applied pressure difference leading to increases the polarization of the concentration on the membrane surface, which should mainly reduce the product flux. But due to the membrane structure, increasing the pressure leads to an increase in the product flux.

In this paper, a one-dimensional simulation for discus plate dielectric barrier discharge (DBD) is done by Comsol Multiphysics software. The effects of different parameters such as voltage, frequency, dielectric thickness, dielectric constant and electrode’ s material on the temperature and density of electrons are investigated, it is found that secondary electron emission coefficient of the electrode, dielectric constant and the thickness of dielectric have a direct impact on the density of electron. The voltage increment from 5 to 50 kV, causes electron density growing from 4×1017m-3 to 3. 2×1018m-3. Based on this study, electron density could reach up to the orders of 1018m-3 by optimizing material and dimensions of dielectric and electrodes without applying high voltage and frequency which results a significant lower production cost.

Numerical simulation is a powerful tool to predict the physical behavior of the designed devices. This method provides detailed information about the investigated phenomenon for each point of the device, which is generally challenging by experiments. Comsol Multiphysics can be utilized in a wide range of engineering fields. This software employs the finite element method (FEM) to solve the physical governing equations. Due to the importance of the heat transfer in advanced ceramics and the potential of the numerical methods to solve the related problems, the present article aims to provide a comprehensive review of the performed numerical research works using Comsol Multiphysics.

Background: Investigating temperature changes and thermal distribution in the interaction of different lasers with various materials has always interested researchers. This study estimated thermal distribution and temperature change of skin, fat, and muscle tissue in interaction with different wavelengths of laser in laser therapy technique for repairing musculoskeletal injuries using Comsol Multi-physics software. Methods: A three-dimensional cube with separate layers and various thicknesses was determined, and then the optical and thermal parameters were determined for materials in different wavelengths. Bio-heat transfer physics in biological tissue was utilized to investigate thermal distribution. In addition, the energy radiated by the laser beam at different wavelengths was considered as a radiant heat source. Results: The results of the calculations by the software showed that different wavelengths of the laser could change the skin temperature up to 38.8 degrees Celsius. However, no noticeable temperature changes were observed in deeper tissues such as muscle tissue. Conclusion: In laser therapy methods for tissue repairing, photochemical phenomena are important, not thermal processes. In the present study, it was proven that temperature changes in tissues are not significant.

Dielectric barrier discharge (DBD) plasma is used for various applications. DBD is also one of the most efficient and low-cost methods for active fluid flow control. In this study, a detailed physical model of DBD in atmospheric pressure at 1 kV DC voltage is developed with Comsol Multiphysics software. Argon gas is also used as a background gas and electrodes are assumed to be copper. Plasma parameters such as electron and ion density, electric field, potential, and temperature for different gap distances of electrodes (1.0 mm, 0.9 mm, 0.8 mm) and different dielectric types (Quartz, Silica Glass, Mica). The results of the simulation show that the longitudinal distance of the grounded electrodes to the power electrodes has a direct influence on parameters such as electron temperature, and electron and ion density which are the main factors of fluid flow control. These parameters have the maximum value when Mica is used as a dielectric and the lowest value when Silica Glass is utilized.

A beta-voltaic battery design can be used to evaluate the functionality of the GEANT4 code and Comsol Multiphysics software. The spatial distribution of the deposited energy for the beta particles in the semiconductor transducer has been simulated by using the GEANT4 and then, the electron-hole pair generation rate has been obtained. Subsequently, output performances of the battery such as the current-voltage (I–, V) characteristics and the maximum electrical power have been determined by using the Comsol Multiphysics in which the electron-hole pair generation rate from the GEANT4 simulation was utilized as input. Validation is done by considering an optimized planar betavoltaic battery. The results of the current study have been compared with other articles. The results are in good agreement and the relative errors are less than 8%. Our simulation model can be extended to the betavoltaic batteries with other semiconductors and radioactive isotopes and can provide a powerful tool for predicting the output performance and optimizing the betavoltaic batteries.

Leachate from waste disposal is recognized as one of the primary sources of groundwater contamination. Therefore, improving the management of landfill sites is crucial for reducing and controlling environmental threats. This study focuses on modeling the dispersion of leachate in a landfill in the city of Isfahan using the finite element method, located 35 kilometers outside the city. The leachate is considered in this area with dimensions of 100 by 250 meters and a depth of 2 centimeters from the bottom. The transmission and spread of pollution across twenty sub-layers of soil have been modeled using Richards' equations and pollution transport equations in porous media. This research utilizes Comsol software to merge different environments using two model equations, and the three-dimensional model investigates the movement and absorption of leachate based on these equations. Meshing in the landfill is done finer in the upper and bottom layers where leachate leakage exists and coarser in the lower parts. Also, mesh modeling in the software is done freely and in a hexagonal shape. According to the findings, the soil under the landfill becomes saturated over time, with the saturation occurring faster in the upper layers. Modeling results show that phosphorus metal pollution has penetrated up to a depth of 1. 8 meters in the soil over 15 years, and leachate has reached approximately 10 meters deep into the ground. Given the proximity of groundwater to the soil surface, measures such as pumping wells and geomembranes must be considered to prevent pollution from entering the groundwater.

The CUSTOM 450 gas turbine compressor blades are corroded in chlorine environments. The initiation and growth of pits and cracks lead to failure. In this paper, prediction of the pitting corrosion behavior of the alloy is studied. In this regard, in the laboratory section, two-point bending specimen is first subjected to different potentials in a 3. 5 wt. % sodium chloride solution to cause pitting corrosion and finally leads to failure at the maximum bending region. According to different potentiostatic tests, an equation is proposed to predict the pitting and life time of stressed sample at different potentials. In the numerical section, the strain in the grown pits is calculated by using digital image correlation method and also the Comsol Multiphysics software. The location of the localized maximum strain obtained from these two methods is in good agreement with growth of the corrosion pits in the electrochemical experiments. Thus, without needs of experiments, the growth direction of the pit can be simulated.