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.

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.

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.

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.

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.

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.

This paper reports on a transient heat, air and moisture transfer (HAM) model. The governing partialdifferential equations are simultaneously solved for temperature and capillary pressure through multi-layered porous media, including the non-linear transfer and storage properties of materials. Using partial differential equations functions, some thermo-physical properties of porous media are converted into coefficients depending on temperature and capillary pressure. Major features of the model are multi-dimensional and transient coupling of heat, air and moisture transport. The coupled equations are solved using the COMSOL Multiphysics time-dependent solver. This solver enables HAM (Heat, Air, Moisture) modeling in porous media. Besides, the good agreements obtained with a 2D benchmark suggest that the model can be used to assess the hygrothermal performance of building envelope components. This paper concludes that the total heat flux in the insulated wall represents only the quarter of that crossing the uninsulated concrete roof. On the other hand, the concrete having the lowest water vapour permeability of all used materials allows maintaining the vapour pressure levels close to the initial value (103 Pa). This induces a situation of interstitial condensation within the concrete of the roof. Being able to evaluate the hygrothermal behaviour, the proposed model may turn out to be a valuable tool to solve other building problems.

The results of time-dependent one-dimensional modelling of a dielectric barrier discharge (DBD) in a nitrogen– oxygen– water vapor mixture at atmospheric pressure are presented. The voltage– current characteristics curves and the productionof active species are studied. The discharge is driven by a sinusoidal alternating high voltage– power supply at 30 kV withfrequency of 27 kHz. The electrodes and the dielectric are assumed to be copper and quartz, respectively. The currentdischarge consists of an electrical breakdown that occurs in each half-period. A detailed description of the electronattachment and detachment processes, surface charge accumulation, charged species recombination, conversion of negativeand positive ions, ion production and losses, excitations and dissociations of molecules are taken into account. Timedependentone-dimensional electron density, electric field, electric potential, electron temperature, densities of reactiveoxygen species (ROS) and reactive nitrogen species (RNS) such as: O, O-, O? , O 2, Oþ 2, O3, N; Nþ 2, N2s and N 2 aresimulated versus time across the gas gap. The results of this work could be used in plasma-based pollutant degradationdevices.