List of Articles Computational Fluid Dynamics

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  1 - Sensitivity Analysis of Constructional Specifications on Thermal Performance of Naturally Ventilated Box Window Double Skin Facade in Hot Arid Climate of Iran (Tehran)
  Faryal sadat Siadati Rima Fayaz Nilofar Nikghadam
  10.30495/hoviatshahr.2022.63836.12114
  The function of the double-skin facade with natural ventilation is based on the thermal performance and airflow of the cavity. Structural features of a naturally ventilated double-skin façade that affect its thermal performance and fluid dynamics include geometri More

  The function of the double-skin facade with natural ventilation is based on the thermal performance and airflow of the cavity. Structural features of a naturally ventilated double-skin façade that affect its thermal performance and fluid dynamics include geometric features such as cavity dimensions, airflow path, air inlet, and outlet areas, shading devices material and their location in the cavity, and material properties that are optical and thermal characteristics of transparent skin. In this research, Fluent Software was used to simulate the computational fluid dynamics, and by sensitivity analysis, the effect of changes in structural properties on thermal performance was evaluated. For this aim, 144 simulation scenarios with cavity depths of 30, 60, 90, and 120 cm, inlet and outlet cross-sections of 0.2, 0.4, and 0.8 m2, louver shadings with 0, 30, 45, 60, and 90 degree angles located at one third distance close to the exterior wall of the façade, the model without shading, exterior glass with regular and low emission layer were investigated, and the following results were obtained:- Cavity Depth: It was observed that as the depth increases, the velocity of airflow in the cavity decreases. Changing the width of the hole changes the surface temperature of the inner glass up to a maximum of 0.80 ° C (up to 2%). As the depth of the cavity increases, the heat flux transmitted through the inner glass surface decreases in most cases (up to 6.5%).- Cross-section: As the cross-section increases, the air velocity in the cavity increases the temperature of the inner glass surface changes irregularly but, in most cases, decreases. In addition, the heat flux passing through the inner glass surface often increases (up to a maximum of 16.3%).- Shading: In the case without shading, the air velocity in the cavity is 0.30 to 0.70 m/s, and in the case with 45 degrees of shading, the air velocity in the cavity is between 0.30 and 0.92 m/s. In the case without shading, the temperature of the inner glass surface changes from 39.3 to 41.0 ° C, and in the case with 45 degrees, changes are between 38.65 to 39.5 ° C. In the case without shading, the heat flux transmitted through the inner glass surface changes from 78.0 to 120.0 W/m2, and in the case with 45 degrees shading, differences between 43.0 to 48.2 W/m2. The sensitivity of the heat flux transmitted through the inner glass surface to the presence or absence of shading can lead to a reduction of the heat flux transmittance through the inner glass surface by up to 61.0%.- Exterior glass type of DSF: In the case without shading, the reduction rate of heat flux from the inner glass surface is 19.44% to 29.78%, and in the case with 45-degree shading is from 17.71% to 24.44%. By changing the exterior glass's material (low emission or regular), the heat flux transmitted through the inner glass surface changes by 32.2 and 120 W/m2.  Manuscript profile
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  2 - Modeling Airflow in Urban Form against Sand Accumulation: a Case of Saltation in the Town of Timimoun in Southern Algeria
  Djamel Mestoul Rafik Bensalem Luc Adolphe
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  3 - Improving efficiency of a gas cyclone in high-temperature operating conditions by using appropriate geometry of vortex finder
  Akbar Jafarnezhad Hesamoddin SALARIAN Saeid Kheradmand Jahanfar Khaleghinia
  Background and Objective: Cyclones are widely used in air pollution control to separate particulate gas mixtures and are used in industry. The advantages of this device in different industries are its relative simplicity of construction, low operating cost and reliable More

  Background and Objective: Cyclones are widely used in air pollution control to separate particulate gas mixtures and are used in industry. The advantages of this device in different industries are its relative simplicity of construction, low operating cost and reliable under extreme working conditions. Today, cyclone separators have become one of the most important particle removal devices in the fields of science and engineering. Due to the wide application of cyclones in industrial processes, especially thermal power plants, the study of the performance of cyclones at high temperatures is of particular importance. In the present study, two-phase flow simulation within a cyclone will be performed in three different dimensions using the Eulerian-Lagrangian approach in order to study the cyclone performance in a wide range of temperatures, and finally the problem of its lower performance will be substantially resolved by using appropriate geometry of vortex finder. Material and Methodology: In this study, the effect of inlet temperature on the flow field and the separation performance of a cyclone has been comprehensively investigated using CFD simulation. The Euler-Lagrangian approach has been used to simulate airflow and particle dynamics in cyclones. In addition, four proposed vortex finder geometries were considered and compared with the basic geometry in order to evaluate how the vortex finder affects the cyclone performance under a wide temperature range (293 K-700 K). The validity of the numerical model is confirmed by comparing the predicted pressure drop with the experimental data and numerical results in which there is a good agreement was achieved. Findings: The results demonstrated that increasing of inlet temperature significantly reduced the tangential velocity and led to a sharp decrease in the cyclone separation efficiency. All of the proposed vortex finders affected the flow pattern within the cyclone at all inlet temperatures. The simulation results showed that the highest tangential velocity observed in the cyclone was with CVF 1, which also had a positive effect on the relevant separation efficiency. Also, it is proved that the proposed cyclone with CVF 1 was able to collect finer particles (2 μm) at high inlet temperature (T = 700 K). Discussion and Conclusion: In the present study, while examining the performance of cyclone using the Eulerian-Lagrangian approach in three dimensions over a wide temperature range, a suitable solution to improve efficiency and solve the problem of efficiency drop at high temperatures was presented. By properly changing the dimensions and geometry of the vortex finder, the flow in the pre-separation zone can be well controlled to improve particle separation efficiency. Manuscript profile
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  4 - Effect of using an airfoil-shaped deflector on increasing the efficiency of a savonius vertical axis wind turbine
  Keyhan Layeghmand Nima Ghiasi Tabari Mehran Zarkesh
  10.30495/jest.2022.55788.5179
  Background and Objective: With the increment of population, the need for sustainable energy development has been raised. By increasing greenhouse gas emissions and decreasing the fossil energy reserves have also shifted research centers around the world to renewable ene More

  Background and Objective: With the increment of population, the need for sustainable energy development has been raised. By increasing greenhouse gas emissions and decreasing the fossil energy reserves have also shifted research centers around the world to renewable energy sources. Among renewable energies, wind energy is one of the most important types of renewable energy. In this study, the efficiency of the Savonius wind turbine is significantly increased by using an airfoil-shaped deflector. This increase in efficiency is carried out by upgrading the self-starting performance capability of the Savonius wind turbine and reducing the negative torque generated by the returning blade. Material and Methodology: Different configurations of the proposed deflector system are considered numerically using the CFD solver. A three-dimensional incompressible unsteady Reynolds-Averaged Navier-Stokes simulation in conjunction with the SST k-ω turbulence model is done and validated with the available experimental data. Findings: The predicted results indicated that the performance of the Savonius rotor is highly dependent on the position and angle of the deflector. Thus, there was an appropriate position and angle values to obtain the highest torque and power coefficients. It was concluded that using the favorable airfoil-shaped deflector significantly enhanced the static torque coefficient values in all angular ranges especially in the rotation angles between 0° to 30° and 150° to 180°. By properly covering the returning blade using the airfoil-shaped deflector, the static torque coefficient values increased up to 2 times higher than that generated by without deflector case. Discussion and Conclusion: The Savonius turbine suffers from poor efficiency. Hence, the present work dealt with proposing an improved deflector system led to generate higher power and torque coefficients which resulted in capturing a higher efficiency and better self-starting capability. Manuscript profile
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  5 - Aerodynamic Simulation of a Container Ship and Evaluation of Cargo Configuration Effect on Fuel Consumption
  Hamed Majidian Farhood Azarsina
  10.22034/jest.2018.13257
  Background and Objective: Iran has access to open seas and plenty of sea transit around it has urged presence of merchant ships in the region. Fuel consumption has always been a matter of concern for ships. In this study, it is attempted to develop computer models for s More

  Background and Objective: Iran has access to open seas and plenty of sea transit around it has urged presence of merchant ships in the region. Fuel consumption has always been a matter of concern for ships. In this study, it is attempted to develop computer models for several container ship cargo configurations and discuss an optimum configuration at a constant speed front wind. Method: The paper presents simulation results using ANSYS CFX commercial software for a Post-Panamax 9000 TEU container ship. The ship is modelled in a 1:4 scale, then using unstructured mesh the wind filed around it is solved. Drag force, drag coefficient, pressure contour and wind streamline velocity in ten different loading conditions are compared with each other. Finally, the optimized container configuration for loading on deck of the vessel is introduced. Findings: Simulation results demonstrate the influence of container configuration on wind load distribution. Also the numerical results are verified versus wind tunnel test data. Finally, the influence of container configurations on fuel consumption and reduction of pollutant emissions was calculated. Discussion and Conclusion: It is proposed to minimize empty spaces between the cargo containers and avoid unbalanced cargo distribution over deck in order to reduce the wind drag force and consequently reduce the fuel consumption and pollutant emissions. Also, it is suggested to make cargo distribution on the forward and aftward deck areas more streamlined. Manuscript profile
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  6 - Design And Numerical Analysis of Propeller for Khazar Dredger
  احد عابدینی سهیل اسدی
  In this article, using a central composite design response surface methodology is that design of the optimal propeller geometry for khazar dredger will be discussed. B_Wageningen standard series is designed propeller-type licenses. To verify the performance and Check no More

  In this article, using a central composite design response surface methodology is that design of the optimal propeller geometry for khazar dredger will be discussed. B_Wageningen standard series is designed propeller-type licenses. To verify the performance and Check non-occurrence of cavitation ,the propeller designed using Computational Fluid Dynamics, numerical modeling and compare with B_Wageningen series. The results show the ability of response surface methodology in finding the optimal geometry propeller. Numerical solution of fluid flow, to prove non-occurrence of cavitation in the propeller designed for kazar dredger. Manuscript profile
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  7 - Evaluating the Efficiency of Different Cover Forms of the Large Spans in Flowers and Plant Exhibitions Based on the Natural Ventilation Vystem in a Moderate and Humid Climate
  Alireza Soltanzadeh Katayoun Taghizadeh Jamshid Emami
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  8 - Effects of Tool Tilt Angle and Plunge Depth on Properties of Polycarbonate FSW Joint
  Hamidreza Mohammadi Kuhbanani Hesameddin Yasemi Hamed Aghajani Derazkola
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  9 - Investigation of no emission in a heat recovery steam generator boiler using computational fluid dynamics
  عباس خوشحال حمید یزدانی
  In this study, NO emission in a HRSG boiler was investigated using CFD. The comparison between the predicted results and measured values showed good agreement, which implied that the adopted combustion and NO formation models are suitable for predicting the characterist More

  In this study, NO emission in a HRSG boiler was investigated using CFD. The comparison between the predicted results and measured values showed good agreement, which implied that the adopted combustion and NO formation models are suitable for predicting the characteristics of the flow, combustion, and NO emission in the boiler. The predicted results showed that the NO formation in the HRSG boiler is quite sensitive to fluid flow, temperature, and oxygen concentration distributions. In addition, the influence of the equivalence ratio at a fixed air mass flow rate on the flame temperature and NO formation was investigated. The results revealed that with increasing the equivalence ratio in the fuel-lean condition, higher flame temperatures established in the boiler and more NO formed. However, in the fuel-rich condition, increasing the equivalence ratio at a fixed air mass flow rate caused a decreasing trend in flame temperature and the NO formation. The maximum flame temperature and NO formation are found at the stoichiometric condition Manuscript profile
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  10 - Heat transfer Simulation of solar wall phase chang materials (PCM) for energy storage and optimization
  Ali Akbar Hosseinjani
  phase change materials have a high capacity in thermal energy storage, these materials can be used to prevent the heat transfer into the building besides optimize and improve the performance of the refrigeration and air conditioning system. Adding phase change materials More

  phase change materials have a high capacity in thermal energy storage, these materials can be used to prevent the heat transfer into the building besides optimize and improve the performance of the refrigeration and air conditioning system. Adding phase change materials (PCM) to the building can improve the inside comfort temperature and save consumption energy of the building. In this article the parameters that affect the performance of PCM in the building walls, such as phase change temperature, latent heat, thickness, thermal conductivity, etc., have been investigated using ANSYS software. the numerical simulation of thermal energy storage in the solar walls of the building have investigated using phase change materials in different thicknesses with different heat flux rates. This wall is designed to capture the sun energy during the day, reducing energy consumption and optimizing it during peak times. Manuscript profile