Arash Karimipour; Behzad Ghasemi
Volume 1, Issue 2 , March 2008
Abstract
A numerical investigation of laminar mixed convection heat transfer in a shallow two-sided lid driven rectangular enclosure of aspect ratio 5, (AR=5) is executed. The natural convection effect is sustained by subjecting the bottom wall to a higher temperature than its top counterpart. In addition, the ...
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A numerical investigation of laminar mixed convection heat transfer in a shallow two-sided lid driven rectangular enclosure of aspect ratio 5, (AR=5) is executed. The natural convection effect is sustained by subjecting the bottom wall to a higher temperature than its top counterpart. In addition, the two horizontal walls of the enclosure are moving in different directions and the two vertical walls of the enclosure are kept insulate. Discretization of the governing equations is achieved through a finite volume scheme. Fluid flow and heat transfer characteristics are examined in the domain of the Richardson number and Grashof number as and while the bottom side of enclosure is moving in two different horizontal directions. The working fluid is assigned a Prandtl number of 0.7, 10 and 100 throughout this investigation. Temporal variations of streamlines, isotherms, and Nusselt number are presented in this investigation for various pertinent dimensionless groups.
MohammadReza Safaiy; Sayed Reza Saleh; Marjan Goudarzi
Volume 1, Issue 2 , March 2008
Abstract
In this work a numerical study of thermal and fluid dynamics behavior of natural air convection in a square cavity in a laminar flow is presented, by finite volume method. The square cavity has two walls heated with different temperatures and two isolated walls. The numerical simulation is made up of ...
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In this work a numerical study of thermal and fluid dynamics behavior of natural air convection in a square cavity in a laminar flow is presented, by finite volume method. The square cavity has two walls heated with different temperatures and two isolated walls. The numerical simulation is made up of several Rayleigh numbers to . Flow and isotherm lines are presented and analyzed. The numerical results presented in this work can be used by researchers who work in the natural convection problem.
Mohammad Akbari
Volume 1, Issue 2 , March 2008
Abstract
The rapid melting of a semi- infinite body due to the absorption of a CW laser beam radiation has been studied. The enthalpy technique for the solution of phase change problems has been used in an explicit finite difference form to calculate the transient temperature distribution in the semi-infinite ...
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The rapid melting of a semi- infinite body due to the absorption of a CW laser beam radiation has been studied. The enthalpy technique for the solution of phase change problems has been used in an explicit finite difference form to calculate the transient temperature distribution in the semi-infinite body and the growth rate of the melt pool. The technique has been modified so that it is not necessary to assign a constant temperature, Tm, to the mesh element that contains the melt front. Instead, a new value of temperature is calculated for the grid point at each time step by incorporating the energy boundary condition at the solid- liquid interface. Calculations have been carried out for laser beam with circular and elliptical profile and for a range of material translational speeds. The numerical results were compared with the experimental data. Increasing the translational speed causes the heat affected zone and the size and shape of melt pool to become smaller.
MohamadMehdi Hemmasian; Manouchehr Rad
Volume 1, Issue 2 , March 2008
Abstract
This paper studied the mathematical method of flow with regard to two-Phase boundary layer that created over the iced surface. Based on experimental results, skin drag over the iced surface compared with this force that compute with slip condition. Based on this results, for iced surface Blasius ...
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This paper studied the mathematical method of flow with regard to two-Phase boundary layer that created over the iced surface. Based on experimental results, skin drag over the iced surface compared with this force that compute with slip condition. Based on this results, for iced surface Blasius equation solving at non-slip condition, can replace with solving the Blasius equation with slip condition. The results are quir acceptable except at small region at the beginning of plate.
Mehdi Zohour
Volume 1, Issue 2 , March 2008
Abstract
In this paper, first design and analysis history of full metal CNG cylinders for vehicle are investigated. Next with respect to the CNG worldwide standards, a full metal type cylinder is designed and analysed. Then the numerical analysis results and practical results are compared, and the correctness ...
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In this paper, first design and analysis history of full metal CNG cylinders for vehicle are investigated. Next with respect to the CNG worldwide standards, a full metal type cylinder is designed and analysed. Then the numerical analysis results and practical results are compared, and the correctness of the investigation is verified. In the end, the most suitable alloy with respect to the dimensions for the purpose of manufacturing of such cylinders is suggested.
Mohsen Lohmousavi; K.I Mori; Mohamad Bakhshi; Mahmoud Farzin; Sayed Jamal Hoseinipour
Volume 1, Issue 2 , March 2008
Abstract
In recent years, the hydroforming due to reduction in weight and increase in strength of automotive parts has attracted attention of the automotive industry. Thus, the knowledge of the process to produce parts with desired quality and accuracy has been growing. One of the effective methods in improving ...
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In recent years, the hydroforming due to reduction in weight and increase in strength of automotive parts has attracted attention of the automotive industry. Thus, the knowledge of the process to produce parts with desired quality and accuracy has been growing. One of the effective methods in improving the formability in the hydroforming is known as pulsating hydroforming. However, the reason of improvement of formability in pulsating hydroforming is still unclear for the closed-die hydroforming of tubes. In this study, the pulsating hydroforming of tube with box die was simulated by the finite element method to examine the effect of pulsating pressure on improvement of formability. In addition, the calculated results are compared with experimental results and it is shown that the improvement of the formability occurs before contact of the tube and die in expansion zone of the tube. Thus, it can be obtained from the results, that the main reason of improvement of the formability is due to the deformation behavior before start of contact of the tube and die.
Kasra Karbaschi; Hasan Hasanzadeh
Volume 1, Issue 2 , March 2008
Abstract
Wide range of planar structures in new technologies has attracted special consideration. In this research vibration behavior of plates with non-linear edges is investigated by means of finite difference (FD) method. For this issue, classical and analytical solutions for plates with linear edges ...
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Wide range of planar structures in new technologies has attracted special consideration. In this research vibration behavior of plates with non-linear edges is investigated by means of finite difference (FD) method. For this issue, classical and analytical solutions for plates with linear edges were analyzed and mutual equations, needed for numerical calculation were extracted. By expanding the current equations to the non-linear edged plates (e.g. elliptical plates), natural frequencies of this special structure were analyzed numerically and computer simulation with ANSYS software. According to the un-existence of classical or analytical solution for this special configuration, closeness of numerical analysis and computer simulation confirms the accuracy of selected method in this study.
AliReza Rezaei
Volume 1, Issue 2 , March 2008
Abstract
A gyroscope is a device for measuring or maintaining orientation, based on the principles of conservation of angular momentum. The device is a spinning wheel or disk whose axle is free to take any orientation. This orientation changes much less in response to a given external torque than it would without ...
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A gyroscope is a device for measuring or maintaining orientation, based on the principles of conservation of angular momentum. The device is a spinning wheel or disk whose axle is free to take any orientation. This orientation changes much less in response to a given external torque than it would without the large angular momentum associated with the gyroscope's high rate of spin. Since external torque is minimized by mounting the device in gimbals, its orientation remains nearly fixed, regardless of any motion of the platform on which it is mounted. A new method of optimization, particle swarm optimization (PSO), is able to accomplish the same goal as GA optimization in a new and faster way. The purpose of this paper is to investigate the foundations and performance of the two algorithms when applied to solve of gyroscope equation.