Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 56 2 2024 04 20 Developing a Coupled Free-Surface Flow Solver using Interface Tracking Algorithm in foam-extend Developing a Coupled Free-Surface Flow Solver using Interface Tracking Algorithm in foam-extend 149 184 5458 10.22060/mej.2024.22507.7635 FA Behnam Cheraghi Faculty of New Sciences and Technologies, University of Tehran 0000-0003-4546-5349 Shidvash Vakilipour Department of Aerospace Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran 0000-0002-6722-4258 Journal Article 2023 06 24 In the present study, the implementation of a coupled implicit solver is presented for solving the free-surface flows. The implementation of the coupled pressure and velocity along with the default interface tracking algorithm has led to the creation of a solver equivalent to the basic foam-extend solver, which is called interTrackFoam. All of the features of the foam-extend platform can still be used i.e. mesh motion and parallel processing. Also, the libraries related to the block matrices available in foam-extend are used in the developed solver. The block matrix system is utilized as the basis of the coupled solver. The single-step solution of pressure and velocity is known as one of the main differences with the default solver. The ability of the developed solver to solve various test cases including a three-dimensional tank, solving the free-surface flow around an airfoil, and the flow passing over the ramp is demonstrated. The simultaneous solution capability has provided the possibility of reducing the number of iterations or considering a relatively higher time step related to solving the flow field. This aforementioned solver is the first step towards the velocity, pressure, temperature, and species-coupled solver with heat and mass transfer capability. In the present study, the implementation of a coupled implicit solver is presented for solving the free-surface flows. The implementation of the coupled pressure and velocity along with the default interface tracking algorithm has led to the creation of a solver equivalent to the basic foam-extend solver, which is called interTrackFoam. All of the features of the foam-extend platform can still be used i.e. mesh motion and parallel processing. Also, the libraries related to the block matrices available in foam-extend are used in the developed solver. The block matrix system is utilized as the basis of the coupled solver. The single-step solution of pressure and velocity is known as one of the main differences with the default solver. The ability of the developed solver to solve various test cases including a three-dimensional tank, solving the free-surface flow around an airfoil, and the flow passing over the ramp is demonstrated. The simultaneous solution capability has provided the possibility of reducing the number of iterations or considering a relatively higher time step related to solving the flow field. This aforementioned solver is the first step towards the velocity, pressure, temperature, and species-coupled solver with heat and mass transfer capability.

https://mej.aut.ac.ir/article_5458_28a543c2a9eee8c0d6fbfaff7ca7e224.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 56 2 2024 04 20 Effect of Various arrangements of piezoelectric beam on Energy Harvesting of Vortex Induced Vibration of Circular Cylinder Effect of Various arrangements of piezoelectric beam on Energy Harvesting of Vortex Induced Vibration of Circular Cylinder 185 212 5456 10.22060/mej.2024.22869.7687 FA Shiva Sharifi Mechanical and Aerospace Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran Ali Esmaeili Mechanical and Aerospace Engineering Department, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad, Iran, 0000-0002-4463-6823 Journal Article 2023 12 17 In this study, in order to harvest energy from the vortex-induced vibration of fluid flow, piezoelectric beams mounted behind a circular cylinder are considered, and the effect of various arrangements of the beams is studied. To reach this goal, a three-way coupling model in the turbulent, unsteady, and viscous flow regime is numerically investigated. The simulations are investigated for different values of electrical resistance and its effect on vibration amplitude, frequency ratio, voltage, and power output are compared. It has been shown that the maximum oscillation amplitude and frequency ratio occurs by a resistance value of 1000 Ω and its value decreases with the increase of resistance. Furthermore, by growing the load resistance, the generated voltage goes up significantly and the maximum voltage is obtained in the load resistance as 100 MΩ, Contrastingly, maximum power is obtained at low values of the load resistance. Finally, it is found that in the parallel arrangement of beams, due to less damping ratio due to stronger interaction between beams and shear layers, larger vibration amplitude, and much more electrical output occurs. In this study, in order to harvest energy from the vortex-induced vibration of fluid flow, piezoelectric beams mounted behind a circular cylinder are considered, and the effect of various arrangements of the beams is studied. To reach this goal, a three-way coupling model in the turbulent, unsteady, and viscous flow regime is numerically investigated. The simulations are investigated for different values of electrical resistance and its effect on vibration amplitude, frequency ratio, voltage, and power output are compared. It has been shown that the maximum oscillation amplitude and frequency ratio occurs by a resistance value of 1000 Ω and its value decreases with the increase of resistance. Furthermore, by growing the load resistance, the generated voltage goes up significantly and the maximum voltage is obtained in the load resistance as 100 MΩ, Contrastingly, maximum power is obtained at low values of the load resistance. Finally, it is found that in the parallel arrangement of beams, due to less damping ratio due to stronger interaction between beams and shear layers, larger vibration amplitude, and much more electrical output occurs.

https://mej.aut.ac.ir/article_5456_a89b71bb5227c75d463dd82a03115738.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 56 2 2024 04 20 Numerical study of bubble growth and collapse dynamics, near the rigid wall Numerical study of bubble growth and collapse dynamics, near the rigid wall 213 240 5462 10.22060/mej.2024.23052.7715 FA Mohammadreza Najafigamasaei Faculty of Mechanical Engineering, Tarbiat Modares University Sajad Khodadadi Faculty of Mechanical Engineering, Tarbiat Modares University Reza Maddahian Faculty of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran Journal Article 2024 03 18 In this study, the dynamics of bubble growth and collapse near a rigid wall is investigated using the modified volume of fluid method and the improved compressible interfoam solver in the OpenFoam open-source code. The research results indicate that the dimensionless gamma number has the most significant impact on the growth and collapse of the bubble near the wall. This study examined two gamma numbers 0.8 and 1.3. It was found that with a 60% increase in the gamma number, the maximum shear stress on the wall decreased by 37%, while the maximum absolute temperature inside the bubble increased by 12%. Additionally, as the gamma number increases, the area affected by the jet impact due to the bubble collapse increases. Within the scope of the present research, the initial pressure parameter of the bubble has the most significant impact on the maximum temperature inside the bubble. In the range of considered initial pressures, a 50% increase in the initial pressure results in a 6% decrease in the maximum temperature of the bubble. However, the values of other studied parameters, such as shear stress, change by less than one percent. In this study, the dynamics of bubble growth and collapse near a rigid wall is investigated using the modified volume of fluid method and the improved compressible interfoam solver in the OpenFoam open-source code. The research results indicate that the dimensionless gamma number has the most significant impact on the growth and collapse of the bubble near the wall. This study examined two gamma numbers 0.8 and 1.3. It was found that with a 60% increase in the gamma number, the maximum shear stress on the wall decreased by 37%, while the maximum absolute temperature inside the bubble increased by 12%. Additionally, as the gamma number increases, the area affected by the jet impact due to the bubble collapse increases. Within the scope of the present research, the initial pressure parameter of the bubble has the most significant impact on the maximum temperature inside the bubble. In the range of considered initial pressures, a 50% increase in the initial pressure results in a 6% decrease in the maximum temperature of the bubble. However, the values of other studied parameters, such as shear stress, change by less than one percent.

https://mej.aut.ac.ir/article_5462_d63c4a5e9b600279c3da776f6113a400.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 56 2 2024 04 20 Analysis and Optimization of Mechanical Properties of Biocomposites Reinforced with Kenaf Fibers/Graphene in the Presence of Compatibilizers Analysis and Optimization of Mechanical Properties of Biocomposites Reinforced with Kenaf Fibers/Graphene in the Presence of Compatibilizers 241 272 5468 10.22060/mej.2024.22798.7679 FA Hossein Taghipoor Department of Mechanical Engineering, Velayat University, Iranshahr, Iran 0000-0002-6019-7461 Jaber Mirzaei Department of Mechanical Engineering, Semnan University, Semnan, Iran 0000-0002-5495-2897 Journal Article 2023 11 12 This article examines the mechanical properties of bio-composites reinforced with kenaf fibers and nano-graphene within a polypropylene matrix by adding a compatibilizer. The response surface methodology with the Box-Behnken approach was used to investigate and present a mathematical model for the behavior of the bio-composite considering the parameters of fiber weight percentage, nano-graphene weight percentage, and compatibilizer weight percentage. The behavior of the samples was analyzed under tensile, bending, and impact tests, and the results were justified using FE-SEM. The fracture surface of the samples indicated that the main mechanism for improving the introduced bio-composite behavior is fiber fracture and fiber pull-out. Multi-objective optimization was carried out using two meta-heuristic methods and the desirability function. The optimization aimed to increase the flexural, impact, and tensile strength while simultaneously reducing the weight of the samples, with the weight percentages of the fibers, nanoparticles, and compatibilizer defined as the problem variables. The results showed that the bio-composite sample with the optimal design parameters has three mechanical properties, including tensile strength, impact strength, and flexural strength, equal to 28.5MPa, 92.29J/m, and 50MPa, respectively. Finally, the optimal state showed that the weight of the bio-composite sample could be reduced by up to 32%. This article examines the mechanical properties of bio-composites reinforced with kenaf fibers and nano-graphene within a polypropylene matrix by adding a compatibilizer. The response surface methodology with the Box-Behnken approach was used to investigate and present a mathematical model for the behavior of the bio-composite considering the parameters of fiber weight percentage, nano-graphene weight percentage, and compatibilizer weight percentage. The behavior of the samples was analyzed under tensile, bending, and impact tests, and the results were justified using FE-SEM. The fracture surface of the samples indicated that the main mechanism for improving the introduced bio-composite behavior is fiber fracture and fiber pull-out. Multi-objective optimization was carried out using two meta-heuristic methods and the desirability function. The optimization aimed to increase the flexural, impact, and tensile strength while simultaneously reducing the weight of the samples, with the weight percentages of the fibers, nanoparticles, and compatibilizer defined as the problem variables. The results showed that the bio-composite sample with the optimal design parameters has three mechanical properties, including tensile strength, impact strength, and flexural strength, equal to 28.5MPa, 92.29J/m, and 50MPa, respectively. Finally, the optimal state showed that the weight of the bio-composite sample could be reduced by up to 32%.

https://mej.aut.ac.ir/article_5468_92dfa194391a59dc65b88b704599dbd6.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 56 2 2024 04 20 Design, build and control the rehabilitation robot to move fingers Design, build and control the rehabilitation robot to move fingers 273 294 5470 10.22060/mej.2024.22947.7700 FA Niloufar Azadi Sohi Department of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran Majid Sadedel Department of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran 0000-0002-0285-8460 Majid Mohammadi Moghadam Department of Mechanical Engineering, Tarbiat Modares University, Tehran, Iran Journal Article 2024 02 05 This research presents the design and development of a prototype fabric-based wearable soft exoskeleton. The soft glove assists the flexion and extension motion of the user’s hand with adjustable speed. The cable method is used to help bending fingers and for extending the fingers, spring blades have been used, the cables are gathered with the help of the gearbox engine and the fingers return to their normal state by reversing the direction of the engine and the force of the springs. With bandwidth modulation circuits and programming in the microcontroller, the movement and speed of the built robot are controlled. In order to determine the appropriate placement of components, including spring blades and cables, robot simulation was performed in SolidWorks software, and with the help of experimental tests, suitable spring blades were selected in terms of strength and force. The resulted soft glove is attached on the human healthy hand for assisting the finger flexion and extension. Based on the test result, the proposed system obtained the highest average for the duration of learning to work with it, which indicates user-friendliness. the parameter related to the feeling of comfort of the fingers in the glove has the lowest average due to the dense structure of the glove. This research presents the design and development of a prototype fabric-based wearable soft exoskeleton. The soft glove assists the flexion and extension motion of the user’s hand with adjustable speed. The cable method is used to help bending fingers and for extending the fingers, spring blades have been used, the cables are gathered with the help of the gearbox engine and the fingers return to their normal state by reversing the direction of the engine and the force of the springs. With bandwidth modulation circuits and programming in the microcontroller, the movement and speed of the built robot are controlled. In order to determine the appropriate placement of components, including spring blades and cables, robot simulation was performed in SolidWorks software, and with the help of experimental tests, suitable spring blades were selected in terms of strength and force. The resulted soft glove is attached on the human healthy hand for assisting the finger flexion and extension. Based on the test result, the proposed system obtained the highest average for the duration of learning to work with it, which indicates user-friendliness. the parameter related to the feeling of comfort of the fingers in the glove has the lowest average due to the dense structure of the glove.

https://mej.aut.ac.ir/article_5470_baed9f51d412c2514ee46a0942138ad6.pdf

Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 56 2 2024 04 20 Evaluating the energy potential of gas synthesis obtained from the destruction and gasification of hazardous hospital waste with a melting-plasma reactor Evaluating the energy potential of gas synthesis obtained from the destruction and gasification of hazardous hospital waste with a melting-plasma reactor 295 318 5471 10.22060/mej.2024.23022.7709 FA Hasan Amirahmadi Department of Mechanical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran 0009-0009-9934-7760 Mohammad Hasan Nobakhti Department of Mechanical Engineering, Faculty of Mechanics, Electricity and Computer, Islamic Azad University, Science and Research Branch,, Tehran, Iran Gholamreza Salehi Department of Mechanical engineering, Islamic Azad University, Central Tehran Branch, Tehran, Iran Shahrooz Saviz Plasma Physics research Center, Science and Research Branch, Azad Islamic University, Tehran, Iran 0000-0001-5874-3761 Journal Article 2024 02 28 The gasification process of hospital waste, unlike traditional methods such as sterilization and burying waste and conventional incineration, has the ability to use the resulting synthetic gas to produce power and electricity in addition to satisfying environmental standards. In this article, the biomedical wastes of Farhikhtegan Hospital in Tehran were gasified with a molten plasma gasifier reactor that has a 90 kW torch. Three parameters of equivalence ratio, temperature, and gasification factor are considered to be effective factors in the molten-plasma gasification reactor, by keeping equivalence ratio parameters and gasification factor fixed, the gasification process was carried out at different temperatures for the gasification reactor and the gas synthesis resulting from It was analyzed elementally and the percentage of gases that make up gas synthesis includes; CO, H2, CO2, and CH4 were determined. At the temperature of 1400 ℃, the amount of CO and H2 gases were measured as 37.1‌% and 32‌%, respectively, and at this temperature, the high heat value (HHV) of the gas synthesis mixture was 9.635 MJ/kg. Also, pollutants such as; H2S, NO2, and SO2 were observed in a very small amount in gas synthesis analysis. In the second phase of this research, the thermodynamic equilibrium modeling of the gasification process of this waste was investigated with Aspen Plus software in the temperature range of 1000 to 1800 ℃. All gasification sub-processes including; Drying, pyrolysis, partial combustion, and regeneration were modeled in equilibrium with the modules in the software. The results of this modeling of the gasification process were in very good agreement with the experimental results. And the next part of the gasification model was combined with the heater turbine, to check the amount of available electricity. The gasification process of hospital waste, unlike traditional methods such as sterilization and burying waste and conventional incineration, has the ability to use the resulting synthetic gas to produce power and electricity in addition to satisfying environmental standards. In this article, the biomedical wastes of Farhikhtegan Hospital in Tehran were gasified with a molten plasma gasifier reactor that has a 90 kW torch. Three parameters of equivalence ratio, temperature, and gasification factor are considered to be effective factors in the molten-plasma gasification reactor, by keeping equivalence ratio parameters and gasification factor fixed, the gasification process was carried out at different temperatures for the gasification reactor and the gas synthesis resulting from It was analyzed elementally and the percentage of gases that make up gas synthesis includes; CO, H2, CO2, and CH4 were determined. At the temperature of 1400 ℃, the amount of CO and H2 gases were measured as 37.1‌% and 32‌%, respectively, and at this temperature, the high heat value (HHV) of the gas synthesis mixture was 9.635 MJ/kg. Also, pollutants such as; H2S, NO2, and SO2 were observed in a very small amount in gas synthesis analysis. In the second phase of this research, the thermodynamic equilibrium modeling of the gasification process of this waste was investigated with Aspen Plus software in the temperature range of 1000 to 1800 ℃. All gasification sub-processes including; Drying, pyrolysis, partial combustion, and regeneration were modeled in equilibrium with the modules in the software. The results of this modeling of the gasification process were in very good agreement with the experimental results. And the next part of the gasification model was combined with the heater turbine, to check the amount of available electricity.

https://mej.aut.ac.ir/article_5471_82836ca597a373e6c3cd5ae2d466161e.pdf