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Flow visualization around a non-circular tube
, Article International Journal of Engineering, Transactions B: Applications ; Volume 19, Issue 1 , 2006 , Pages 73-82 ; 1728-144X (ISSN) ; Lavasani, A. M ; Sharif University of Technology
Materials and Energy Research Center
2006
Abstract
The flow behavior around a cam shaped tube in a cross flow has been investigated experimentally using flow visualization and pressure distribution measurements. The range of attack angle and Reynolds number based on an equivalent circular diameter are within 0 < α < 360° and 2×104Reeq <3.4×104, respectively. The pressure drag features are clarified in relation to the flow behavior around the tube. It is found that the highest pressure drag coefficient occurs at α = 90° and 270° over the whole range of Reynolds number. Results show that the pressure drag coefficient of the cam - shaped tube is lower than that of a circular tube with the same surface area for more of the attack angles
Velocity distributions in (r,θ) directions for laminar flow of a film around horizontal circular tube
, Article 2006 ASME Joint U.S.- European Fluids Engineering Division Summer Meeting, FEDSM2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 1 SYMPOSIA , 2006 , Pages 11-19 ; 0791847500 (ISBN); 9780791847503 (ISBN) ; Saidi, M. H ; Sharif University of Technology
American Society of Mechanical Engineers
2006
Abstract
Velocity distributions in (r,θ) directions are evaluated by solving simultaneous simplified Navier-Stokes equations (NSE) and continuity equation (CE) in polar coordinate. The analysis is based on steady state laminar flow of thin falling liquid film on a horizontal circular tube, for cases in which traction on the film surface is considered negligible. It is a common geometry for part of engineering problems such as evaporator, condenser, absorber, generator of absorption chillers and other similar units in mechanical and chemical engineering. Knowledge of the velocity profiles is usually needed for: 1 - solving governing energy and species equations 2- estimating the average and film...
Velocity distributions in (r,θ) directions for laminar flow of a film around horizontal circular tube
, Article 2006 2nd ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 2006 , 2006 ; 0791837831 (ISBN); 9780791837832 (ISBN) ; Saidi, M. H ; Sharif University of Technology
2006
Abstract
Velocity distributions in (r,θ) directions are evaluated by solving simultaneous simplified Navier-Stokes equations (NSE) and continuity equation (CE) in polar coordinate. The analysis is based on steady state laminar flow of thin falling liquid film on a horizontal circular tube, for cases in which traction on the film surface is considered negligible. It is a common geometry for part of engineering problems such as evaporator, condenser, absorber, generator of absorption chillers and other similar units in mechanical and chemical engineering. Knowledge of the velocity profiles is usually needed for: 1- solving governing energy and species equations 2- estimating the average and film...
Energy absorption in plastic expansion of circular metal tubes
, Article Computational Plasticity X - Fundamentals and Applications, 2 September 2009 through 4 September 2009, Barcelona ; 2009 ; 9788496736696 (ISBN) ; Salehghaffari, S ; Sharif University of Technology
Abstract
This paper investigates a new method of dissipating energy in which a rigid tube is driven into the deformable tube under axial compression. Since there is a specific clearance between the rigid and deformable tubes, the deformable tube is expanded during axial compression, and the impact energy is absorbed by plastic expansion of deformable tube and frictional energy between deformable and rigid tubes. Quasi-static axial compression tests with different values of friction coefficient between rigid and deformable tubes are performed. Theoretical formulation with consideration of strain hardening effect is presented to predict the mean crushing load. Theoretical and experimental studies show...
Pressure loss and heat transfer characterization of a cam-shaped cylinder at different orientations
, Article Journal of Heat Transfer ; Volume 130, Issue 12 , September , 2008 , Pages 1-4 ; 00221481 (ISSN) ; Lavasani, A. M ; Sharif University of Technology
2008
Abstract
Pressure drag coefficient and heat transfer are experimentally investigated around a single noncircular cylinder in cross-flow under angle of attack 0 deg<α>360 deg and Reynolds number 1.5*104
Pressure loss and heat transfer characterization of a camshaped cylinder at different orientations
, Article Journal of Heat Transfer ; Volume 130, Issue 12 , September , 2008 , Pages 1245031-1245034 ; 00221481 (ISSN) ; Lavasani, A. M ; Sharif University of Technology
2008
Abstract
Pressure drag coefficient and heat transfer are experimentally investigated around a single noncircular cylinder in cross-flow under angle of attack O deg < α < 360 deg and Reynolds number 1.5 × 104 < Reeq < 4.8 × 104 based on equivalent diameter of a circular cylinder. The results show that the trend of pressure drag coefficient against the angle of attack has a wavy shape but the wavy trend of the Nusselt number is smoother relative to the drag coefficient behavior. It is found that for l/Deq = 0.4 and over the whole range of the Reynolds number, the pressure drag coefficient has a minimum value of about CD = 0.4 at α = 30 deg, 180 deg, and 330 deg and a maximum value of about CD = 0.9 at...
Three-dimensional data transfer operators in plasticity using SPR technique with C0, C1 and C2 continuity
, Article Scientia Iranica ; Volume 15, Issue 5 , 2008 , Pages 554-567 ; 10263098 (ISSN) ; Gharehbaghi, S. A ; Sharif University of Technology
Sharif University of Technology
2008
Abstract
In this paper, the data transfer operators are developed in three-dimensional elasto-plasticity using the Superconvergent Patch Recovery (SPR) method. The transfer operators are defined for mapping of the state and internal variables between different meshes. The internal variables are transferred from Gauss points of old mesh to the nodal points. The variables are then transferred from the nodal points of old mesh to the nodal points of new mesh. Finally, the values are computed at the Gauss points of new mesh using their values at the nodal points. Aspects of the transfer operators are presented in a three-dimensional superconvergent path recovery technique, based on C0, C1 and C2...
A constitutive model for shape memory polymers with application to torsion of prismatic bars
, Article Journal of Intelligent Material Systems and Structures ; Volume 23, Issue 2 , 2012 , Pages 107-116 ; 1045389X (ISSN) ; Naghdabadi, R ; Arghavani, J ; Sohrabpour, S ; Sharif University of Technology
Abstract
In this article, satisfying the second law of thermodynamics, we present a 3D constitutive model for shape memory polymers. The model is based on an additive decomposition of the strain into four parts. Also, evolution laws for internal variables during both cooling and heating processes are proposed. Since temperature has considerable effect on the shape memory polymer behavior, for simulation of a shape memory polymer-based structure, it is required to perform a heat-transfer analysis. Commonly, an experimentally observed temperature rate-dependent behavior of shape memory polymers is justified by a rate-dependent glassy temperature, but using the heat-transfer analysis, it is shown that...
Thermal study of the internal flow in a circular tube with vibrational ball turbulators
, Article International Journal of Heat and Mass Transfer ; Volume 196 , 2022 ; 00179310 (ISSN) ; Aghlichanche, A ; Ataelahi, A ; Mohammadi, O ; Shafii, M. B ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Flow turbulators have promising heat transfer applications. Here, the novel design proposed in our previous study (vibrational ball turbulators, VBTs, mounted on an elastic wire inside a circular tube) is investigated experimentally from heat transfer and thermal performance standpoints. The effects of diameter (Y) and longitudinal distance (pitch, X) ratios of VBTs, the Reynolds number, and the axial tension of the wire (σ0) on the average Nusselt number (Nu), the average Nusselt number ratio (Nu divided by that of a plain tube, Nup), the friction factor ratio (f/fp), and a parameter called the thermal performance factor (η=(Nu/Nup)/(f/fp)1/3) are studied. Different ball diameter (Y=0.3,...