Comsol Multiphysics Simulation Research Papers (original) (raw)

This paper presents a numerical modeling approach for hygrothermal behavior of bio-based materials. The mathematical model describes the heat and moisture transfer through a wall of biobased materials. The studied wall is subjected to both convective heat transfer and moisture flux transfer with the surroundings. Moreover, a parametric study was performed to analyze the effect of varying the model's key parameters on the overall thermal performance of the wall. Consequently, an optimal proposal can be suggested to attain the main objective, which is
reducing energy consumption for winter heating and summer cooling

- by and +1
- •
- Heat Transfer, Heat and Mass Transfer, Comsol Multiphysics Simulation

GaAs/GaAlAs/GaAs Asymmetric Quantum Wells (AQW) have shown in the past multiple advantages in the domain of inter-sub-band transition (ISBT) while serving as the basic structures for advanced electro-optical devices. A new approach enables to create and control the modulation of Self-Induced Electrical Fields (SIEF), as a function of the dopant concentration variation in the structure. Combined numerical and analytical analyses present a smart way to design such structures towards their future integration in advanced devices. The results are obtained by means of Comsol software which needed solid and creative adaptations in order to deal with this kind of challenging structure.

- by Avi Karsenty and +1
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- Modeling and Simulation, Asymmetry, Comsol Multiphysics Simulation, Quantum Well

Plasma Arc Welding (PAW) is one of the important arc welding processes used in electronics, medical, automotive and aerospace industries due its high accuracy and ability of welding any hard materials. Though PAW is more complex and requires more expensive equipment compared to other commercial arc welding processes, it finds application in automotive sectors. In automotive applications, titanium metal is used particularly in motorcycle racing, where weight reduction is critical while maintaining high strength and rigidity. Titanium is in the group of reactive metals, which means that they have a good affinity for oxygen and readily forms an oxide layer leads to oxygen embrittlement. Therefore, the welding of titanium sheets is still an emerging technology in automotive sectors. The present investigation deals with the numerical simulation of plasma arc welding of 2 mm thick Ti-6Al-4V alloy using Finite Element code COMSOL. A Modified Three Dimensional Conical (MTDC) heat source model and a newly developed heat source model are considered for performing the numerical simulation to predict the temperature distribution on thin sheets of titanium alloy. The temperature dependent material properties of Ti-6Al-4V such as thermal conductivity, specific heat and density are used for performing the numerical analysis. Based on the results, it is observed that the predicted weld bead geometry from the temperature distribution plots using newly developed heat source model is in good agreement with the corresponding experimental result.

- by Dhinakaran Veeman
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- Welding Simulation, Comsol Multiphysics Simulation

Workers at mineral processing facilities are often exposed to high levels of dust generated when ores are processed. Crushing, grinding, screening, and other processes generate large quantities of dust, which can exceed the threshold values prescribed by the Mine Safety and Health Administration (MSHA). Many ores contain quartz (silica), which has been known to cause serious health problems in workers over time. Given the structure of mineral processing plants, the airflow regime is not coherent inside the building, which may lead to multiple recirculation zones. These recirculation zones can trap dust, and concentrations of dust can then rise over time. Therefore, there is a need to understand the airflow phenomenon that occur inside of mineral processing facilities and how these occurrences interact with the dust generation processes to identify zones of potentially high dust concentration. Computational fluid dynamics (CFD) modeling can give a better understanding of the airflow and help recommend designs and methods to mitigate the high dust concentrations in a mineral processing plant. This paper presents the CFD modeling of airflow inside of a mill building to demonstrate airflow patterns that will affect the generation and subsequent dispersion of dust due to crushing, grinding, and other activities. This study was conducted by researchers from the National Institute for Occupational Safety and Health (NIOSH).

Abstract: Arterial disease, especially Coronary Artery Disease (CAD) is one of the leading causes of premature morbidity and mortality. During the flow, blood not only interacts with vessel wall mechanically but also chemically which modulates the plaque formation in blood vessel thus leading to coronary artery diseases. Here we propose to simulate a MEMS based flexible flow sensor based on anemometer principle which is designed to integrate at a catheter tip.

- by DEBASHIS MAJI and +2
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- PDMS, Comsol Multiphysics Simulation, Flexible Electronics

- by Fatemeh Shahbazi
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- Materials Science, Design, Nanobiotechnology and Biosensors, Optimization

This is an example of fluid flow in a micro channel coupled with a surface reaction taking place along the channel walls. A small concentration of a biological analyte is mixed with the fluid. The flow velocity is so small that the concentration of the analyte is transported to the reaction surface where it binds to an antibody ligand, mainly by diffusion through the fluid.

Studies of the electrical, thermal, and mechanical stresses on power cables have received much attention in recent years. However, there is a research gap in studying the electromagnetic forces of the power cables of electric arc furnaces (EAFs). The challenges of studying the EAF's power cable are highlighted because of the special cyclic operations, inrush currents, current harmonics, and short circuit faults of the EAF. The electromagnetic forces are influenced by the magnitude current and behavior of the current passing through the cable. The main purpose of this paper is to respond to a research gap about studying the electromagnetic forces of EAF's power cables under different normal and abnormal conditions. The proposed study is implemented in the COMSOL Multiphysics environment. Test results of applying the proposed method to an actual test system highlight the advantages of the proposed study. Simulation results imply that current harmonics, particularly the 7th harmonic order, intensify the electromagnetic forces. Test results emphasize the impacts of short circuit currents on the induced electromagnetic force. Furthermore, test results show that although cable clips limit the cable movement, internal von Mises cable stress increase due to the deployment of cable clips.

- by Hamed Hashemi-dezaki and +1
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- Electrical Engineering, Finite element method, Electromechanical Engineering, Comsol Multiphysics Simulation

Biosensors are favored devices for the fast and cost-effective detection of biological species without the need for laboratories. Microfluidic integration with biosensors has advanced their capabilities in selectivity, sensitivity, controllability, and conducting multiple binding assays simultaneously. Despite all the improvements, their design and fabrication are still challenging and time-consuming. The current study aims to enhance microfluidic-integrated biosensors’ performance. Three different functional designs are presented with both active (with the help of electroosmotic flow) and passive (geometry optimization) methods. For validation and further studies, these solutions are applied to an experimental setup for DNA hybridization. The numerical results for the original case have been validated with the experimental data from previous literature. Convection, diffusion, migration, and hybridization of DNA strands during the hybridization process have been simulated with finite element method (FEM) in 3D. Based on the results, increasing the velocity on top of the functionalized surface, by reducing the thickness of the microchamber in that area, would increase the speed of surface coverage by up to 62%. An active flow control with the help of electric field would increase this speed by 32%. In addition, other essential parameters in the fabrication of the microchamber, such as changes in pressure and bulk concentration, have been studied. The suggested designs are simple, applicable and cost-effective, and would not add extra challenges to the fabrication process. Overall, the effect of the geometry of the microchamber on the time and effectiveness of biosensors is inevitable. More studies on the geometry optimization of the microchamber and position of the electrodes using machine learning methods would be beneficial in future works.

In this book, a multi-physics approach to the modeling and analysis of nuclear reactor core behavior is presented, and applied to study the dynamics of Molten Salt Reactors (MSR). The Multi-Physics Modeling (MPM) approach is implemented in a unified simulation environment, which results able to catch the synergy between the different phenomena involved in the
reactor core behavior, whose modeling would otherwise require either the adoption of existing simulation tools with drastic modifications of their structure and possible loss of significant information or the development of purpose-made numerical codes for the specific analyzed situation.
The book is organized into four chapters, which are conceived so as to be read independently of each other. Here, the rationale of the R&D activities performed at the Politecnico di Milano by the authors, and giving rise to the book contents, is briefly outlined.
In the last years, MSRs have been the subject of a growing and renewed interest from the scientific community in the framework of the Generation IV International Forum. Due to the availability of an advanced conceptual design, the Molten Salt Breeder Reactor (MSBR) developed at the Oak Ridge
National Laboratory during the 1960s is usually considered in the literature as reference system for benchmark analyses and validation purposes. Coherently, the MSBR has been chosen as reference configuration for the analyses presented in the book. In such kind of Circulating Fuel Reactor (CFR), like the other MSRs, the coupling between neutronics and thermo-hydrodynamics is a key issue. This feature cannot be neglected in order to perform an adequate description of the reactor dynamic behavior, which shows peculiar aspects with respect to solid-fuelled conventional nuclear power plants. Relevant differences in terms of safety, fuel cycle and technology also distinguish the MSRs from the other nuclear reactors (Chapter 1).
The developed MPM methodology and the adopted models for neutronics and thermo-hydrodynamics required a deep investigation for what concerns the assessment and the extension of the simulation environment, represented in the specific case by the finite element COMSOL Multiphysics® software (chosen thanks to its flexible and modular numerical structure), but the same methodology can be applied to other multi-physics platforms. As far as thermo-hydrodynamics is concerned, a generalized approach was developed (Chapter 2) and exploited for the assessment of COMSOL simulations
(Chapter 3), making use of a dedicated finite volume computational fluid dynamics code (FLUENT®), in order to better appreciate the differences in numerical approaches to turbulence. The generalized approach was built in order to carefully take into account the molten salt mixture specificities (i.e., a fuel that operates also as coolant), the reactor core power conditions and the heat transfer in graphite. In this context, a Nusselt number correlation was developed, which takes into account the effect of internal heat generation on
fluid heat transfer characteristics. As far as neutronics is concerned, a module for the "reactor physics" was built in the COMSOL environment of simulation, and allowed to extend the potentialities of this computing platform. Numerical results were assessed by means of: (i) a code-to-code comparison with
dedicated neutron transport codes, in the case of static fuel; (ii) a comparison with simplified neutron kinetics models, representative of the zero-power dynamics, in the case of circulating fuel.
After the assessment of the COMSOL capabilities to cope with the adopted models for neutronics and thermo-hydrodynamics, the MPM approach was applied to study the dynamic behavior of a single-channel representative of the average conditions of the MSBR core (Chapter 4). For this case study, the MPM approach resulted particularly suitable because of the strong nonlinear coupling between the fuel motion and neutron dynamics, which requires a careful description of the time-space distribution of the physical quantities. Several different transients were analyzed, such as those driven by: reactivity variations due to control rod movements; fuel mass flow rate variations due to the change of the primary pump working conditions; presence of periodic perturbations, due to local precipitation of fissile solid compounds within the molten salt mixture. The analyses gave significant information on the MSBR dynamic behavior and highlighted the several advantages and potentialities offered by the proposed MPM approach (for instance, the "modularity", namely the possibility to include other physical phenomena and couplings).
These potentialities are of more general interest in the prospect of studying the design configuration, the dynamics and the control strategy of next generation MSRs, as well as of other nuclear reactor types.

Insulations are the most important part of high voltage equipment such as cables and machines. Therefore the study of the condition and mechanism of failure of high voltage insulations is important. In this paper the electric field and potential distribution in the insulation of stator bar are studied. In particular, the effects of the size and location of the void in the insulation are investigated. COMSOL software was used to carry out the simulation based on the finite element method (FEM). A 2D modeling of stator bar insulation was used in this work. The results show the electric field is affected by the size and location of the void in the insulation, in terms of the field strength and uniformity. The results of this work to help improve the understanding of the electric field response due to the size and location of void within the stator bar insulation. [Hadi Nabipour-Afrouzi, Zulkurnain Abdul-Malek, Saeed Vahabi-Mashak. Study on Effect of Size and Location of Void on Electric Field and Potential Distributions in Stator Bar Insulation with finite-element-model. Life Sci J 2013;10(4):2036-2041]. (ISSN:1097-8135). http://www.lifesciencesite.com. 270

- by Saeed Vahabi
- •
- Comsol Multiphysics Simulation, Electric Field

The main objective of this paper work is to optimize the welding parameters such that the maximum temperature in the work piece material reaches up to 80-90% of melting point of base material in friction stir welding of aluminum plates. Friction stir welding (FSW), invented and established by The Welding Institute (TWI) in 1991 amongst the emerging new welding technologies, is used frequently for welding of high strength aluminum alloys which are difficult to weld by conventional fusion welding techniques. Friction stir welding (FSW) is a relatively new welding process that may have significant advantages compared to the fusion processes as follow: joining of conventionally non-fusion weldable alloys, reduced distortion and improved mechanical properties of weldable alloys joints due to the pure solid-state joining of metals. The study of microstructure and flow of material around the welding tool during friction stir welding (FSW) is closely linked to many of the key issues related to the process. The heat source in this model is the friction between the material and the probe and the shoulder. For understanding the FSW thermo mechanical process, the thermal history in the friction stirred weld is simulated numerically. It is necessary that the model can be further to optimize the FSW process in order to minimize peak temperature within process window. The welding process was simulated using COMSOL MULTIPHYSICS software and developed thermal profile. Modeling and simulation of FSW has been a great challenge due to the complexity of the process. The results clears that an increase in the rotational speed and coefficient of friction causes increase in the peak temperature in workpeice. The simulation result is compared to available experimental results. According to results in steady state model, when tool is at center in process the temperature is not maximum at center but slightly front of the tool, this is due to preheating in the workpeice.

The numerical simulations of low-pressure radio-frequency (RF) inductively coupled argon discharge are carried out by using the finite element method (FEM) based on COMSOL Multiphysics® software program. Two-dimensional axisymmetric ICP model is used to compute the axial and the radial profiles of the electron density (n e), the electron temperature (T e) and the plasma potential (V p). The axial analyses are obtained at two different gas pressures 30 and 40 mTorr for a fixed r=10 cm and P=300 Watt. While the radial measurements are done at P= 200, 300 and 400 Watt for a fixed z=4 cm and p=30 mTorr.

Different analytical and numerical methods are commonly used to solve transient heat conduction problems. In this problem, the use of Alternating Direct Implicit scheme (ADI) was adopted to solve temperature variation within an infinitesimal long bar of a square cross-section. The bottom right quadrant of the square cross-section of the bar was selected. The surface of the bar was maintained at constant temperature and temperature variation within the bar was evaluated within a time frame. The Laplace equation governing the 2dimesional heat conduction was solved by iterative schemes as a result of the time variation. The modelled problem using COMSOL-MULTIPHYSICS software validated the result of the ADI analysis. On comparing the Modelled results from COMSOL MULTIPHYSICS and the results from ADI iterative scheme graphically, there was an high level of agreement between both results.

Solar photovoltaic (PV) cells are semiconductor devices that convert solar energy to electricity using photovoltaic effect. These cells are commonly known as solar cells, or solar panels, and in 2012 around 93 terawatt-hours (TWh) of electricity was produced, which is enough to power over 20 million homes. When designing solar panels, it is important all parameters are taken into account in order to minimize the losses. In this paper we discuss two main solar energy generation devices namely Solar Dish receiver and Solar panel array. We have varied various parameters of the solar dish array and simulated using COMSOL Multiphysics how these parameters have an effect on the efficiency of the receiver. Also, we have designed the model for solar array and simulated the effect of fluid flow load (wind speed 54km/hr) on the solar panel efficiency.

- by Tithi Desai
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- Solar Energy, Solar Power, Comsol Multiphysics Simulation

In this paper a MV (medium voltage) of 11 KV XLPE (cross linked polyethylene) power cable is implemented in COMSOL MULTIPHYSICS. This software simulates the results based on FEM (Finite Element Method) in order to know the stress effects of electric field in the formation of water trees. Water voids form when there is mechanical damage while laying directly or buried in ducts and water penetrates through the cable sheath. So the impurities fill the cable and result in treeing which develops slowly. The results show the field effect is more at the corners of the ellipse shaped water void which direct radial outwards from the cable axis. This maximum value of electric field causes the formation of channels between the micro cavities which further leads to breakdown.

- by Raquel Cumeras and +1
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- Ion mobility spectrometry, Comsol Multiphysics Simulation

The modeling of conjugate development of fractures and fluid flow remains a significant subject in a diversity of rock engineering. Continuum numerical methods are paramount in the modeling of rock engineering practice problems, merely with restrained capacities in modeling the problem of fracture development coupled by fluid flow. There exists a demand for them to be understood in details. Driven by this, we demonstrated an approach based on a three-dimensional development of fracture of an abstract model condensed to two-dimensional analysis comprising rocks with fractures. In the framework of a continuum method of modeling, the contact between the fracture development and deformation was paired with fluid flow. A 3-D model was established in this case for a shale reservoir and fluid was injected at multiple pressures to understand the initiation and propagation of fractures, as applied to the field of hydraulic fracturing. The stress, strain, displacement in the reservoir were monitored at multiple injection pressures. Linear relations of injection pressures were observed with these parameters. A detailed insight with quantification of the values is given into the subject based on the findings of this study.

Ferrofluid sloshing vibration energy harvesters are the recent addition in the domain of vibration energy harvesting systems. These systems are unique in using a liquid state transduction mechanism to harvest ambient vibrations/oscillations to generate electric power. In this paper, a 2-D representation of one such system is numerically simulated. The simulation consists of interface tracking between air and ferrofluid via the level-set method, modeling permanent magnets using the AC/DC module, and the general incompressible Navier-Stokes equations using the CFD Module. To establish the accuracy of the simulation, grid convergence studies are performed. Secondly, an additional validation of numerical algorithms in COMSOL is performed by mimicking a published experimental configuration for Ferrofluid Vibration Energy Harvesting. The extracted RMS voltages from the experimental results and COMSOL numerical simulation agree within 5% of the variance. Finally, the proposed system with four permanent magnets is analyzed.

- by nadish anand and +1
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- Level Set Methods, Ferrofluids, Comsol Multiphysics Simulation, Vibration Energy Harvesting

In this experiment-based research, the performance and behaviour of a pouch type Li-ion battery cell are reported. The commercial test cell has a Lithium Titanate Oxide (LTO) based anode with 13Ah capacity. It is accomplished by measuring the evolution of surface temperature distribution, and the heat flux of the battery cell at the same time. Temperatures on the surface of the cell are measured using contact thermocouples, whereas, the heat flux is measured simultaneously by the isothermal calorimeter. This heat flux measurement is used for determining the heat generation inside the cell. Consequently, using the heat generation result the important performance constituent of the battery cell efficiency is calculated. Those are accomplished at different temperature levels (-5°C, 10°C, 25°C and 40°C) of continuous charge and discharge constant current rate (1C,2C,4C,8C,10C (maximum)). There is a significant change in heat generation in both charge and discharge events on different temperature and Crate. The heat flux change level is non-linear. This nonlinear heat flux is responsible for the nonlinear change of efficiency in different Crate in a particular temperature. The presented experimental technique is a very precise determination to profile the battery cell. The result of the research can be incorporated in constructing a precise datasheet for a battery cell which can assist the researchers, engineers, and different stakeholders to enhance different aspects of battery research. Keywords— Surface temperature; spatial distribution; Isothermal Calorimeter; Lithium Titanate Oxide (LTO), Battery thermal management, battery efficiency, heat Generation, key performance indicator (KPI), battery behaviour.

- by Mohammad Rezwan Khan and +1
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- Lithium-Ion Battery, Multiphysics, Comsol Multiphysics Simulation, Battery Thermal Management System for EVs/HEVs

ABSTRACT Ground Source Heat Pumps (GSHPs) have received significant attention in recent years because of their energy efficiency. Most studies are interested in the performance of GSHPs. However, little research has been done on the underground temperature distribution and change affected by GSHPs. This study set up a numerical model in Comsol Multiphysics and simulated the underground temperature over 100 years. The long-term underground temperature around an energy pile was investigated without considering groundwater movement. Parameters and boundary conditions were examined before the simulation. The temperature changes at different depths and distances were presented. Temperature decreases were found in half-compensation and no-compensation conditions, and the decrease processes were found happened mainly within the first decade.

- by Xianglei Zheng
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- Comsol Multiphysics Simulation, GSHP

In solar thermal energy storage systems the operation modes involve charging and discharging. This paper focuses only on the charging leading to an endothermic reaction and therefore an efficient heat exchanger is required to transfer the heat for fast and complete charging. Two different heat exchangers are studied in this paper. A plate fin and helical coil heat exchangers embedded in a magnesium chloride bed is modelled and solved using the software Comsol 4.3a based on finite element method. Meshing analysis is performed for parameters sensibility and the results show a temperature variation of 13 °C (helical coil) and 19 °C (plate fin) in the material bed during the charging mode of the thermochemical heat storage system. The pressure distribution in the heat transfer fluid and the temperature distribution in the material bed are presented and the calculated overall heat transfer coefficient of 173 W/m2•K (helical coil) and 236 W/m2•K (plate-fin) are obtained on the base of the total heat transferred (Q) to through the system. The fluid flow is in turbulence regime (Re = 13200) in the fin-plate, but in laminar mode (can be kept up to Re = 20000) [1] in the coil because the flow is affected by secondary flow cause by centrifugal forces. This study allows the choice of the heat exchanger wherein with first experiment has been made and compared.

- by Prof. Armand Fopah Lele and +1
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- Heat Transfer, Heat Exchanger, Solar Energy, Comsol Multiphysics Simulation

A three-dimensional multiphysics-based thermal model of a battery pack is presented. The model is intended to demonstrate the cooling mechanism inside the battery pack. Heat transfer (HT) and computational fluid dynamics (CFD) physics are coupled for both time-dependent and steady-state simulation. Inside the battery cells in the pack a lumped value of heat generation (HG), that works as a volumetric heat source, is used. The measured HG stems from the cell level isothermal calorimeter experiment. The batteries inside the pack stay in the same initial thermal state in the simulation case. The pack is simulated to find the temperature gradient over the pack surfaces. Moreover, the temperature evolution results are simulated. It is demonstrated that the developed pack model can provide the thermal spatio-temporal behaviour with great detail. The result helps to understand the thermal behavior of the cells inside a battery pack.

- by Mohammad Rezwan Khan
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- Smart Grid, Lithium-Ion Battery, Battery, battery management system (BMS)

In the present work a three dimensional finite element thermal analysis of friction stir welding has been carried out in Comsol Multiphysics software. In the present model only heat generation due to friction is considered. The thermal profile obtained from the simulation has shown good agreement with the previously published experimental results. Three factors viz. axial force, welding speed and rpm each having three different levels was studied. The optimization of the process parameters for maximum temperature has been carried out by Taguchi method based on Taguchi's L9 orthogonal array. In this approach, each response ie. Temperature is transferred to corresponding signal to noise ratio by using Taguchi's larger the better criterion (LBT). The optimum welding parameters obtained after the analysis are F=5000N, S=80 mm/min and N= 1600 rpm. A conformation test is conducted by using these process parameters. The maximum temperature obtained was 590.62⁰C which is 89.4 % of melting temperature of the material.

We know the mechanical properties of silicon. However, little is known about the mechanical properties of silicon solar cells. Modeling is widely used in the study of solar cells. This article discusses in detail the effect of mechanical stress on solar cells. To do this, a model of the solar cell was created and simulated at Comsol Multiphysics. The results were presented visually and graphically. The results were tested for relevance and accuracy.

- by Jasurbek Gulomov
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- Solar Cell, Simulation, Comsol Multiphysics Simulation, Mechanical Stress

Carbon capture and storage (CCS) projects require an accurate evaluation of the sealing potential of faults and highly fractured zones to minimize the potential for CO2 leakage. A study on the control exerted by fracture and fault networks on fluid flow, and in particular on CO2 leakage, should be based upon a representation of discrete fracture networks (DFN) that is as close as possible to that observed in the field. Due to post-lithogenetic fracturing or weathering, coal matrix can contain complex dual porosity structure, which makes it difficult to identify the fluid flow behavior through it. Although CO2-enhanced coal bed methane (ECBM) recovery has been comprehensively investigated, the impact of coal matrix-fracture interactions on the evolution of coal permeability under in-situ conditions is still unclear. In this studies laminar flow models was developed to explicitly quantify the flow behavior of CO2 gas through dual solid media (coal matrix and fracture). A numerical simulation model was developed to simulate flow profiles and fluid flow in COMSOL Multiphysics. The COMSOL Multiphysics model closely predicts the gas flow through the porous coal matrix sample for the range of confining and gas injection pressures studied in low gas flow rates (laminar flow). COMSOL Multiphysics model uses DarcyÃ¢â‚¬â„¢s law and FrickÃ¢â‚¬â„¢s law for flow simulations. The graphical relations between velocities, pressure, shear stress etc. with Height and Width displacement was studied in this investigation.

A simple, readily available SERS substrate was investigated by utilizing the metallic layer of commercially available DVDs. The channel-like regions could trap metal NPs creating 'hotspots". Au nanoparticles fabricated using fs laser... more

A B S T R A C T The significance of geometrical and physical parameters of hollow fiber membrane modules in the membrane distillation process has not been fully evaluated. In this study, we develop a three-dimensional multi-physics model of a hollow fiber membrane module in order to investigate the effect of operating and design parameters on the module performance. The permeate flux and thermal efficiency of the system are considered as the characteristic parameters of the module, operated in direct contact membrane distillation mode (DCMD). The simulation results indicate that the permeate flux for the module can be enhanced by 54% when 1) the hollow fibers are in close-packed configuration, and 2) the interspacing parameter, the ratio of a fiber radius to the center-to-center distance between neighboring fibers, is adjusted properly. We identify the fiber interspacing parameter as a critical parameter for the module design. The permeate flux significantly drops when the in-terspacing parameter is equal to a value of 0.5, implying that the fibers are adjacent to each other. Moreover, the results indicate that, in our system, the time constant for the mass transfer process through the membrane is higher than that of heat transfer, meaning that the DCMD process for a hollow fiber membrane module under parallel flow condition is a mass transfer limited process.

Although a large number of previous researches have significantly contributed to the understanding of the quasi-static mechanical behavior of cemented tailings backfill, an evolutive porous medium used in underground mine cavities, very few efforts have been made to improve the knowledge on its response under sudden dynamic loading during the curing process. In fact, there is a great need for such information given that cemented backfill structures are often subjected to blast loadings due to mine ex-ploitations. In this study, a coupled thermo-hydro-mechanical-chemical (THMC)-viscoplastic cap model is developed to describe the behavior of cementing mine backfill material under blast loading. A THMC model for cemented backfill is adopted to evaluate its behavior and evolution of its properties in curing processes with coupled thermal, hydraulic, mechanical and chemical factors. Then, the model is coupled to a Perzyna type of viscoplastic model with a modified smooth surface cap envelope and a variable bulk modulus, in order to reasonably capture the nonlinear and rate-dependent behaviors of the cemented tailings backfill under blast loading. All of the parameters required for the variable-modulus viscoplastic cap model were obtained by applying the THMC model to reproducing evolution of cemented paste backfill (CPB) properties in the curing process. Thus, the behavior of hydrating cemented backfill under high-rate impacts can be evaluated under any curing time of concern. The validation results of the proposed model indicate a good agreement between the experimental and the simulated results. The authors believe that the proposed model will contribute to a better understanding of the performance of hydrating cemented backfill under blasting, and also to practical risk management of backfill structures associated with such a dynamic condition.

- by Mamadou Fall and +1
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- Viscoplasticity, Blast and impact engineering, Multiphysics, Comsol Multiphysics Simulation

In this article a solid-fluid interaction in an open loop and finger skirt is considered. The combined loop and finger skirt takes advantage of flexibility of the finger and stability benefits of the loop. On the other hand, compare to the other skirt types, it is a difficult skirt to design. We consider the loop and finger skirt as a flexible structure which is in interaction with air flow. The gradual expansion and deformation of loop and fingers are important design parameters which are considered in this paper. We made a finite element analysis of the skirt system to find the large deformation and stresses of the skirt. Adjacent fingers are in contact and move with respect to each other. As a result we have a frictional contact problem. This phenomenal is also study in different cases using different loadings, and boundary conditions. Three dimensional (3D) geometrical model of the problem is considered. Different materials are also used in our analysis.

- by Mehrdad Javidi and +1
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- Finite Element Methods, Finite Element Analysis (Engineering), Fluid structure interaction, Comsol Multiphysics Simulation

Hot air is required in many engineering applications such as heating spaces and drying food. Solar air heater is used to heat air in an environmentally-friendly way. The solar air heater consists of many components that are worthy to be studied to improve its performance. In the present study, the influence of air space height, between absorber and glass cover, on the air temperature and the mass flow rate at the exit of the solar air heater was experimentally and numerically investigated. Further, the temperature distribution along the heater absorber was numerically exhibited. The studied heights of air space were 3, 5, 7, and 9 cm. Experimentally, four identical solar air heaters, each had different air space, were designed and constructed. Numerically, COMSOL Multiphysics ® software was adopted. The used implemented modules were Heat transfer in fluids and Laminar flow. In addition, surface-to-ambient radiation was used. The properties of air flowing through the air solar heater were based on that available in Material Browser. A comparison was performed between the experimental and numerical results, and an acceptable agreement was found with a deviation of 4.6% for the outlet air temperature and 6.8% for the air mass flow rate. The results showed that the highest air outlet temperature was gained with the narrowest space, particularly 88.95 °C at 3 cm. While the highest mass flow rate was gained with the widest space, i.e. 9.41 g/s at 9 cm.

Drinking water contamination is a major cause for multiple diseases and deaths in humans. Currently detection and characterization of drinkable water is expensive and time consuming due to culture formation. Here, we present a flexible sensor consist of an Inter-digitated electrodes (IDEs) on a polyethylene terephthalate (PET) substrate and it is compatible for integration through additive printing techniques. The sensor structure is simulated for electrical characterization in COMSOL Multiphysics. Further, by using LC formation, the resonating behavior is also analyzed in Ansys High Frequency Structure Simulation (HFSS) for RF characterization. The sensor detected the presence of bacteria in water as the capacitance and resistance of the sensor reduced by 5.2 pF and 363 kΩ, respectively, as compared to the values of pure water. While using HFSS, the sensor detected the bacterial presence by showing the resonance frequency response of 4.075 GHz and 4.175 GHz for pure and Escherichia Coli contaminated water, respectively.

- by Muhammad Awais
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- Comsol Multiphysics Simulation, HFSS

ABSTRACT Heat storage systems using reversible chemical solid-fluid reactions to store and release thermal energy operates in charging and discharging phases. During last three decades, discussions on thermal decomposition of several salt-hydrates were done (experimentally and numerically) [1,2]. A mathematical model of heat and mass transfer in fixed bed reactor for heat storage is proposed based on a set of partial differential equations (PDEs). Beside the physical phenomena, the chemical reaction is considered via the balances or conservations of mass, extent conversion and energy in the reactor. These PDEs are numerically solved by means of the finite element method using Comsol Multiphysics 4.3a. The objective of this paper is to describe an adaptive modeling approach and establish a correct set of PDEs describing the physical system and appropriate parameters for simulating the thermal decomposition process. In this paper, kinetic behavior as stated by the ICTAC committee [3] to understand transport phenomena and reactions mechanism in gas and solid phases is taking into account using the generalized Prout-Tompkins equation with modifications based on thermal analysis experiments. The model is then applied to two thermochemical materials CaCl2 and MgCl2 with experimental activation energies and a comparison is made with TGA-DSC measurement results.

- by Wolfgang Ruck and +1
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- Chemical Engineering, Materials Science, Numerical Modelling, Heat and Mass Transfer

Electrical Capacitance Tomography is a modality
which enables users to visualize and monitor the process flow in a
closed pipe. It is a non-invasive and non-intrusive technique, yet,
it suffers from soft-field effect which produces low resolution
images. Segmented excitation is proposed in this paper to
overcome the problem faced by ECT single excitation. The
comparison between single and segmented excitation are
presented in form of images and electrical potential value. From
the 1st switching, segmented excitation recorded 315% higher
electrical potential compared to single excitation at the center of
the pipe. From simulations, sensitivity maps are generated and
compared between both excitation methods. The electrical
potential for segmented excitation is well-distributed and
produces 164% higher of average electrical potential compared
to single excitation method.

- by Aizat Utm and +1
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- Modeling and Simulation, Tomography, Comsol Multi Physics, Comsol Multiphysics Simulation

Heat storage systems using reversible chemical solid-fluid reactions to store and release thermal energy operates in charging and discharging phases. During last three decades, discussions on thermal decomposition of several salt-hydrates were done (experimentally and numerically) [1,2]. A mathematical model of heat and mass transfer in fixed bed reactor for heat storage is proposed based on a set of partial differential equations (PDEs). Beside the physical phenomena, the chemical reaction is considered via the balances or conservations of mass, extent conversion and energy in the reactor. These PDEs are numerically solved by means of the finite element method using Comsol Multiphysics 4.3a. The objective of this paper is to describe an adaptive modeling approach and establish a correct set of PDEs describing the physical system and appropriate parameters for simulating the thermal decomposition process. In this paper, kinetic behavior as stated by the ICTAC committee [3] to understand transport phenomena and reactions mechanism in gas and solid phases is taking into account using the generalized Prout-Tompkins equation with modifications based on thermal analysis experiments. The model is then applied to two thermochemical materials CaCl2 and MgCl2 with experimental activation energies and a comparison is made with TGA-DSC measurement results.

- by Prof. Armand Fopah Lele and +1
- •
- Chemical Engineering, Materials Science, Numerical Modelling, Heat and Mass Transfer

ÖZET Bu çalışmanın esas amacı, parametrik optimizasyonu yapılmış olan iki-ızgaralı silindir yapıdaki indüktif-eşli radyo frekanslı plazma (RF-ICP) iyon iticilerinin niceliksel itki ve I sp analizlerini yapmaktır. Bu silindirik itici tasarımının simülasyonlarını yapmak için, COMSOL Multiphysics® yazılım programı kullanılmıştır. İtki sistemi, 300 W RF gücüyle, farklı gaz basınçlarında (30-230 mTorr) çalıştırılmıştır. Özgül itme hesapları için, hızlandırma potansiyeli 1110 V olarak alınmış ve yapılan hesaplar sonucunda, itki değerleri 0.411 mN, özgül itme ise 7459 saniye olarak hesaplanmıştır. GİRİŞ Günümüzde, basit ve kompakt bir tasarıma sahip olan plazma iticilerinin popülerliği, giderek artmaktadır. Bunun en önemli nedenlerinden biri gerçeğe en yakın modelleme sonuçları sağlamalarıdır. Bu tip iticilerden olan indüktif-eşli radio frekanslı plazma (RF-ICP) iyon iticileri de yüksek özgül itme ve yüksek verim sağladıklarından dolayı en çok tercih edilenlerdendir. İlk defa 1960 yılında, Alman bilim adamı Profesör Horst Loeb, RF-ICP iticileri üzerine araştırmalar yapmaya başladı. Daha sonra, 1922 yılında,Loebìn araştırmaları öncülüğünde RIT 10 adı verilen itici EURECA uydusu üzerine yerleştirildi [Dobkevicius, 2017]. RF-ICP iyon iticileri, uzay araçlarının itişinde kullanılan bir tür roket motorlarıdır. Bu tip sistemlerin fiziksel çalışma prensipleri elektrohidrodinamik itkiye dayanmaktadır. RF-ICP iticiler, elektrot kullanmadan indüktif deşarj ile iyon üretmektedirler. Bu sayede katot erozyonun sebep olduğu negatif etkiler ortadan kalkar ve iticilerin ömrü daha uzun olur. Ayrıca bu tip iticilerde iyon üretimi ve hızlandırma mekanizmaları birbirinden bağımsız olduğundan daha az RF gücü ile çalışabilen ve daha küçük ebatlarda iticiler üretilebilmektedir. RF-ICP iyon iticileri Şekil-1`de görüldüğü gibi beş ana bölümden oluşmaktadır; plazma odası, RF bobinleri, RF jeneratörü ve uyarlama (matching) sistemi, iyon optik sistemi (IOS-ekran ızgarası, hızlandırıcı ızgarası ve yavaşlatma ızgarası) ve bir nötrleştirici. Genellikle, bu tip sistemlerde iletken ve atom numarasının büyük olmasından dolayı yakıt (ortam gazı) olarak Xenon gazı kullanılır [Tsay, 2010]. Plazma odacığında (anotta) bulunan nötr Xenon gazı, RF jeneratöründen uygulanan güç yardımıyla iyonize edilerek plazma oluşturulur. Odacığın etrafına sarılmış olan bobinlerin oluşturduğu elektromanyetik alanların ve hızlandırıcı ızgaraya uygulanan yüksek voltajın etkisiyle de iyonlar hızlandırılarak odacığın dışına doğru püskürtülür. Dışarıda püskürtülerek oluşan iyon hüzmesi de bir oyuk katot yardımıyla nötralize edilir. Böylelikle iticinin yük dengesi korunur [Dobkevicius, 2017].

Receptor plays an essential role in determining the efficiency of lightning strike protection on wind turbine blades. To investigate the effects of receptors with different shapes and sizes on the lightning strike protection, we apply five different receptor configurations to the blade of a high fidelity wind turbine model. The static electric field strength on the blade surfaces due to a lightning stepped leader is predicted through the development of a numerical model with finite element analysis. The interception efficiency is evaluated by comparing the predicted maximum electric field strength in the vicinity of the receptors. In addition, the locations of the predicted lightning strike attachment points match well with those obtained by experimental measurements, which validate the current numerical approach.

- by Yeqing Wang
- •
- Wind Energy, Comsol Multi Physics, Wind turbine, Lightning

The Coulomb criterion, which requires that both the shear and normal stress on an incipient fault plane satisfy critical conditions, is the most widely used condition of the rock failure. Changes in Coulomb stress associated with one or more earthquakes may trigger subsequent events and produce an aftershock series, where faults are optimally orientated for failure as a result of the stress change caused by the main shock. The Coulomb-3 software calculates the Coulomb failure stress changes directly from the co-seismic slip data. The calculations are made in an elastic halfspace with uniform isotropic elastic properties following the analytical solution of Okada (1992) and thus ignore effects associated with the crustal structure.
The COMSOL software operates with a final element grid and enables to account the complex structure of the simulated domain. COMSOL calculates the whole stress tensor in every volumetric grid element which is used, then it calculates the Coulomb failure stress changes. First, we run a series of benchmarking simulations for homogeneous crust and compare the results with those obtained using the Coulomb-3 software. Then, we repeat the modeling for the flat layered structure. The results present a significant difference (in scale of 1.6 [bar]) of the Coulomb failure stress changes simulations received images. This difference increases with the depth and extend value of maximal change around 6.3 [bar] at the deep of 21.64 km (depth of the mantle).
The last series of simulations were performed for the study area including the southern part of the Dead Sea transform, from the Arava Valley to the Nuweiba-at the Gulf of Eilat. The crustal structure was constructed using the available geophysical observations (seismic profiles, Gulf of Eilat-bathymetric data and else). The model consists of four layers: the sedimentary succession, the seismic basement and the upper mantle. Stress simulations were performed using co-seismic slip data from the 3-D earthquake modeling based on integrated seismological and INSAR data for the November 22, 1995 Nuweiba earthquake (Baer et al., 2008). The comparison between the results of homogeneous and flat layered models to those obtained for the structural model demonstrate that the Coulomb failure stress change distribution is significantly affected by the heterogeneity of the study area. The difference is around 9 [bar], that increase with the depth and extends maximal change value around 10 [bar].

- by Mariana Belferman
- •
- Earth Sciences, Geophysics, Modeling, Modeling and Simulation

• MHD natural convection in a quadrantal enclosure filled with nanofluid is studied. • Rayleigh number, Hartmann number and nanofluid volume fraction effects are studied. • Average Nusselt number decreases with Ha, especially at higher Ra... more

Fluctuations in groundwater levels along the coast have a significant impact on the extent of saltwater intrusion into freshwater aquifers. This study aims to simulate the groundwater Cow and solute transport in the region by using the mSim toolbox in the MATLAB and COMSOL Multiphysics. The investigation is focussed on a micro-basin of Pavanje river located along the west coast of India. The model results are calibrated and validated against the Beld observations. The results show that the variation of the water table over the year is significant and range from about 3-14 m. There exists a reasonable correlation between the simulated and observed values of groundwater level and salinity. The wells that are most vulnerable to seawater intrusion in the region are identiBed. The COMSOL model estimated a salinity range of 0-20 mol/m 3. Additionally, the model is used to understand the response of coastal aquifer to various stress scenarios. The study reveals that reduced recharge rate with increased pumping has a serious impact on aquifer system.

- by Surajit Deb Barma
- •
- Geology, Hydrology, Matlab, Comsol Multiphysics Simulation
- by Adnene TLILI
- •
- Residual Stress (Engineering), Matlab, Comsol Multi Physics, Matlab Programming

Modulator (PWM) is used to control the solenoid valve operation. In addition to the above a thermal analysis for the fixed PV modules and the piping water is presented where the output water temperatures, rate of heat transfer, overall heat transfer coefficient and thermal efficiency are calculated. As a result, a significant enhancement in the total thermal efficiency is observed with acceptable increase in the output water temperature.

- by Editor IJRET
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- Renewable Energy, Matlab, Hybrid, Comsol Multiphysics Simulation

This article, a part of the larger research project of Surface-Enhanced Raman Scattering (SERS), describes an advanced study focusing on the shapes and materials of Tip-Enhanced Raman Scattering (TERS) designated to serve as part of a novel imager device. The initial aim was to define the optimal shape of the “probe”: tip or cavity, round or sharp. The investigations focused on the effect of shape (hemi-sphere, hemispheroid, ellipsoidal cavity, ellipsoidal rod, nano-cone), and the effect of material (Ag, Au, Al) on enhancement, as well as the effect of excitation wavelengths on the electric field. Complementary results were collected: numerical simulations consolidated with analytical models, based on solid assumptions. Preliminary experimental results of fabrication and structural characterization are also presented. Thorough analyses were performed around critical parameters, such as the plasmonic metal—Silver, Aluminium or Gold—using Rakic model, the tip geometry—sphere, spheroid, ellipsoid, nano-cone, nano-shell, rod, cavity—and the geometry of the plasmonic array: cross-talk in multiple nanostructures. These combined outcomes result in an optimized TERS design for a large number of applications.

- by Avi Karsenty and +1
- •
- Light Scattering, Nano-photonics and plasmonics, Absorption, Comsol Multiphysics Simulation

This paper reports preliminary results concerning thermal effects induced by urban/industrial air pollutants deposited on a limestone rock when heated by pulsed laser in the cleaning process. The process of laser cleaning treatment of the crust is simulated using COMSOL Multiphysics 4.4, finite element analysis software. Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy and Laser Induced Breakdown Spectroscopy techniques have been used to analyze the chemical composition of the samples. Two elements found as being present into the dust and in the crust, such as iron and magnesium particles are used for simulation in COMSOL. Therefore, the profiles heat evolutions on the crust surface and inside limestone are obtained as thermal interactions between the three components (iron, magnesium and limestone), simulating the non-homogeneous materials. It has been observed that iron impurities caused by the dust deposition may damage the limestone through a process of overheating, as a consequence of a high thermal conduction phenomenon, recorded for the region with iron impurities and sizes of micrometric order are localized. The thermal contact between the three components results in plots that reflect their thermal interactions.

- by Felicia Iacomi
- •
- Materials Science, Multidisciplinary, Limestone, Laser Ablation

In this research, we have used the COMSOL Multiphysisc software to solve differential equations, analyzing the parameters by finite element method in the piezoelectric and the sound wave propagating environments. We have built the hard PZT piezoelectric ceramic plate model and designed the Langevin transducer model and horn head transducer from the PZT piezoelectric ceramic plate. Surveying the design model effect to the characteristic parameters, we have reasearched the impedance characteristics by the frequency and identifed the resonance frequency, the near field sound pressure level and the emitted ultrasonic wave at the far field by the frequency of the two transducer types. This is the basis for selecting the design model to accord with the application purpose. Index Terms-Langevin transducer; horn head transducer; PZT hard piezoelectric ceramic; sound pressure level; COMSOL-Multiphysics.

— A direct simulation investigations of contaminant transport has been conducted. The simulations are based on the unsteady longitudinal advection diffusion contaminant decay equation, which is discretized using finite element Galerkin's method with backward difference time formulation with the application of COMSOL Multiphysics Software Package. It was observed that the simulation results, which are illustrated pictorially via line graphs and contours, consistently represented the analytical solutions of Mebine and George (2011), thereby demonstrating interesting features of the problem effected by the variety of contaminant decay time-dependent sources.

- by Engineering Journal Publication of Research work
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- Engineering, Air pollution, Research, Dispersion

The electrical output parameters and mode shapes of multiple piezoelectric unimorph cantilever beams (UCB's) with same thickness and different length reported and examined. Connecting arrays of 5 commercial unimorph beams made of polyvinylidene difluoride (PVDF) in series showed widening in the bandwidth and increasing in the power magnitude of energy harvester comparing to single unimorph beam. The output power was increased from 2 µW to 5 µW and the bandwidth was widened from (47, 55) Hz to (22, 88) Hz. Finite element analysis (FEA) was used to investigate about the first fifth mode shapes of the suggested system using COMSOL multi-physics, with a good agreement between model and experiment.

- by nadish anand and +1
- •
- Level Set Methods, Ferrofluids, Comsol Multiphysics Simulation, Vibration Energy Harvesting