List of Articles Drag coefficient

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  1 - Wind tunnel flow simulation and aerodynamic shape optimization of tall buildings to improve the drag coefficient under wind forces
  Abdollah Baghaei Daemei seyed rahman eghbali Hossein Moez Payam Bahrami
  Aerodynamic behavior is an important characteristic of tall and ductile buildings, so aerodynamic design can play a key role in reducing the wind effects. A tall building response to wind can be controlled by application of aerodynamic improvements to building’s d More

  Aerodynamic behavior is an important characteristic of tall and ductile buildings, so aerodynamic design can play a key role in reducing the wind effects. A tall building response to wind can be controlled by application of aerodynamic improvements to building’s design in order to manipulate the wind flow pattern and break the effective wind force acting on the structure. Traditionally the approach of structural engineers to mitigating wind loading and associated deflections and motions on tall buildings was to stiffen the building with the aim of increasing the natural frequency. Tall buildings are extremely sensitive to the wind. Thus, assessment of wind loads to design these buildings is essential. Monitoring the wind, which is forcing extraordinary tall buildings, is highly challenging. Due to increasing construction in recent decades, the study on wind flow over tall buildings has become a popular subject in theoretical research and applied engineering applications. By looking at recent constructions in Iran, it is obvious that despite the fact that constructing tall buildings is spreading, there is less concentration on environmental factors such as the wind’s aerodynamic. In tall buildings, aerodynamic behavior generally becomes important. The wind-induced building response of tall buildings can be reduced by means of aerodynamic from design and modifications that change the flow pattern around the building or break up the wind affecting the building face. Aerodynamic-based design can be divided into two types, “aerodynamic architectural design” and “aerodynamic architectural modifications” and their subgroups. The accurate estimation of the critical response parameters, such as top floor accelerations and displacements, is of fundamental importance when ensuring reliable designs of tall buildings. Methods to this end are typically set in a modal analysis framework and therefore require the estimation of the generalized forcing functions. Tall buildings are particularly prone to dynamic excitations such as those from natural disasters like strong winds and earthquakes, and this has become an especially important design issue. One way to minimize wind-induced vibrations of tall buildings is to focus more on their shapes in the design stage. Investigated aerodynamic forces and wind pressures acting on tall buildings with various unconventional configurations. The proposed of this research, investigation of aerodynamic shape optimization on tall buildings in order to reduce drag force. The aerodynamic forms such as a set-back, tapered and helical (twisted) and also aerodynamic modifications such as a chamfered corner, rounded corner and recessed corner to control and reduce wind forces and vortices on tall buildings are considered. On this basis, the study was carried out with numerical simulation of wind tunnel test on 29 building models. In order to construct 3D models, AutoCAD 2014 software was deployed and also to numerically simulate wind tunnel Autodesk Flow Design 2014 is used. Building samples were entered into the software via format FBX. The results showed that for a tall building with a triangular footprint and height of about 150 meters, base shape with chamfered corners of aerodynamic modification and tapered of aerodynamic form can have the best aerodynamic behavior against wind forces. Manuscript profile
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  2 - Investigating the wind-induced effects on Tall Buildings to reduce Drag Coefficient through Large Eddy Simulation (LES)
  Najmeh Mastari Farahani Abdollah Baghaei Daemei Payam Madelat Seyedeh Maryam Abbaszadegan
  10.30495/ijaud.2022.67658.1612
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  3 - Numerical Solution of PDE for MHD flow around a sharp geometry at high Mach and altitudes and its effect on drag and lift coefficients
  S.M. Hosseini Mohammad Hatami Aziz Vazifehshenas
  In this paper, the effect of magneto-hydrodynamic flow on two aerodynamic geometries (2D & 3D) is investigated. The results (Lift and drag coefficients) for two and three-dimensional geometries, which have been tried to be similar to rocket wings, at high altitudes More

  In this paper, the effect of magneto-hydrodynamic flow on two aerodynamic geometries (2D & 3D) is investigated. The results (Lift and drag coefficients) for two and three-dimensional geometries, which have been tried to be similar to rocket wings, at high altitudes where the pressure is high and the temperature low, as well as Machs at 6 and 8 and at 9 different angles of attacks, are obtained in two modes with and without magnets. At the end, it was observed that adding a magnet to the problem increases the lift coefficient which maximum increment (77.5%) occurred for 3D geometry at Mach 8 and 50000 m height. Also, comparing the two-dimensional and three-dimensional geometries, it was observed that the stall angle did not occur in the two-dimensional geometry at 9000 altitude and Mach 6, but in the three-dimensional geometry and the same conditions, the stall angle was observed for the non-MHD mode, which is due to flow line of two-dimensional geometry. However, it was further observed that this angle was delayed by adding a magnet to the 3D geometry with the mentioned solution conditions. Manuscript profile
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  4 - Experimental study of the characteristics of the wake and drag coefficient changes of a car model in unsteady flow
  V. Barzanooni A.B. Khoshnevis
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  5 - Experimental Investigation of the Flow Control of Wake Cylinder by a Plate with Different Geometrical Ends
  A.B. Khoshnevis AmirReza Mamouri AmirReza Mamouri V. Barzenoni
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  6 - Investigation of the Hydrodynamic Analysis of a Ballistic Body Using Simulator Software
  مقومی مقومی علی کاهید باصری
  During movement in different flying levels, ballistic objects can endure various forces, which depend on the strength of different parts of the intended body at the time of their design and manufacturing. Among the forces resulting from aerodynamic equations, lift and d More

  During movement in different flying levels, ballistic objects can endure various forces, which depend on the strength of different parts of the intended body at the time of their design and manufacturing. Among the forces resulting from aerodynamic equations, lift and drag forces could be noted. These two forces depend on characteristics such as the angle of attack. In the present paper, a Shahab-3 ballistic missile (manufactured in Iran) has been evaluated by simulating in the software Najm. This software can be used to analyze the ballistic objects. This work were analyzed in two stages, once with the attack angle of 2 degree and once again with the angle equal to 8 degree. After performing the investigations, it was determined that in the attack angle of 2 degree the forces created in the body of ballistic object do not develop any critical pressure or tension. However, in the attack angle of 8 degree, the lateral pressure starts from the length of 8 m from the object’s tip and it reaches the critical point in the end area, which complies with reality. Moreover, the lift-to-drag coefficient ratio that is considered as a characteristic of aerodynamic analysis is much more suitable for angle of 2 degree. Manuscript profile
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  7 - Drag reducing of Peogeut 405 using the vortex generator.
  Rouhollah Ghodsi Hamidreza Zomorodi Farhad Emamalizadeh
  Abstract The flow separation at the rear of a vehicle generates more pressure drag. A vortex generator can cause delay in developing of separation by chang-ing the distribution of momentum in boundary layer. The comparison be-tween the results of with and without vorte More

  Abstract The flow separation at the rear of a vehicle generates more pressure drag. A vortex generator can cause delay in developing of separation by chang-ing the distribution of momentum in boundary layer. The comparison be-tween the results of with and without vortex generator reveals the effects of vortex generator on drag reduction considerably. In this study, an effi-cient vortex generator is designed for the Peugeot 405 sedan. The numeri-cal simulations are performed using ANSYS FLUENT and also the model and mesh are generated by ICEM. Manuscript profile
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  8 - Numerical study of the effect of vortex generators arrangement on vehicle aerodynamic characteristics
  morteza khayat
  Land vehicles are among the blunt body objects. When a vehicle moves forward, the movement of air around it produces a pressure gradient that varies along the body. This can lead to separation and appearance of a turbulent wake region in the rear of the vehicle. The pre More

  Land vehicles are among the blunt body objects. When a vehicle moves forward, the movement of air around it produces a pressure gradient that varies along the body. This can lead to separation and appearance of a turbulent wake region in the rear of the vehicle. The present study numerically investigates the aerodynamic effects of vortex generators and their arrangement in different positions of 6 and 15 numbers, each with linear, rectangular and triangular arrangements on the back of a car model. Reynolds-Averaged Navier-Stokes (RANS) equations and turbulent models have been used to analyze the changes in drag and lift coefficients obtained from different arrangements of the vortex generators. The results show that the best case for reducing the drag force is related to 6 numbers of vortex generators with linear and triangular arrangement, which reduces the drag coefficient by 2% compared to the car model without vortex generators. In addition, the best case to improve the downforce; in order to increase the stability of the car, is the arrangement of 15 vortex generators with a rectangular alignment, which reduces the lift coefficient by 23.1% compared to the car model without the vortex generator. Also, with increasing the number of vortex generators from 6 to 15, the drag coefficients generally increase. Manuscript profile