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open-channel-flow
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Hydraulic behaviour of flow over an oblique weir
, Article Journal of Hydraulic Research ; Volume 48, Issue 5 , 2010 , Pages 669-673 ; 00221686 (ISSN) ; Ansari, A ; Borghei, S. M ; Sharif University of Technology
2010
Abstract
A comprehensive set of experiments was performed on weirs placed obliquely in a rectangular open channel. The main objectives were to investigate the effect of the weir angle relative to the approach flow direction on the behaviour and the hydraulic flow characteristics and to examine methods such as using upstream guide vanes and inclined aprons to increase the effective oblique weir length. Results indicate that by increasing the oblique angle, the effective length of the oblique weir increases significantly. Relationships are provided for the threshold submergence and the effective length of the oblique weir. Design recommendations are also presented for the use of guide vanes and...
Local scour at open-channel junctions
, Article Journal of Hydraulic Research ; Volume 48, Issue 4 , Sep , 2010 , Pages 538-542 ; 00221686 (ISSN) ; Jabbari Sahebari, A ; Sharif University of Technology
2010
Abstract
High bed-shear stress resulting from secondary flows and velocity increase at a channel junction cause local erosion and deposition in natural rivers and earth-lined channels. Herein, the scour patterns at the junction of two loose bed channels were studied under clear-water conditions. The main dimensionless variables are the angle between the two approach flow branches, the discharge and width ratios of the tributary to the downstream channel branches, and the ratio of the mean downstream velocity to the threshold velocity. The results indicate that the position of the maximum scour depth temporally moves to the outer wall and upstream to the main channel, as affected by the dimensionless...
Effect of a standing baffle on the flow structure in a rectangular open channel
, Article Journal of Hydraulic Research ; Volume 48, Issue 3 , Jun , 2010 , Pages 400-404 ; 00221686 (ISSN) ; Takeda, Y ; Firoozabadi, B ; Sharif University of Technology
2010
Abstract
The effect of an intermediate standing baffle on the flow structure in a rectangular open channel has been investigated by a three-dimensional acoustic Doppler velocimeter. Investigation of time-averaged velocity profiles at different streamwise positions reveals that the approach flow is fully developed upstream of the baffle. By analysing the space-averaged power spectra of streamwise velocity, a peak structure was observed in the upstream baffle region. Downstream of the baffle this peak structure has been alleviated by the baffle. The same analysis for the vertical component indicates the existence of a peak structure both up- and downstream of the baffle. Consequently, a baffle affects...
Determination of discharge coefficient of triangular labyrinth side weirs with one and two cycles using the nonlinear PLS method
, Article Sustainable Hydraulics in the Era of Global Change - Proceedings of the 4th European Congress of the International Association of Hydroenvironment engineering and Research, IAHR 2016, 27 July 2016 through 29 July 2016 ; 2016 , Pages 653-657 ; 9781138029774 (ISBN) ; Parvaneh, A ; Kabiri Samani, A ; Sharif University of Technology
CRC Press/Balkema
2016
Abstract
Side weirs are hydraulic control structures widely used in irrigation, drainage networks and waste water treatment plants. These structures can be used for adjusting and diverting of flow with minimum energy loss. In spite of many studies were carried out on rectangular side weirs, the studies on oblique and labyrinth side weirs are scarce. In this study, based on the experimental data from more than 210 laboratory tests and through using the multivariable nonlinear partial least square (PLS) method, two nonlinear equations are presented for discharge coefficient CM of triangular labyrinth side weirs with one and two cycles. The obtained empirical equations relating CM with the relevant...
Dynamic identification of inelastic shear frames by using Prandtl-Ishlinskii model
, Article 18th IASTED International Conference on Modelling and Simulation, MOAS 2007, Montreal, QC, 30 May 2007 through 1 June 2007 ; 2007 , Pages 284-288 ; 10218181 (ISSN) ; 9780889866638 (ISBN) ; Joghataie, A ; Sharif University of Technology
2007
Abstract
In this paper, a new method is proposed for the identification of inelastic shear frame structures with hysteresis, using data collected on their dynamic response. It uses the Prandtl-Ishlinskii rate independent model for hysteresis. The proposed identification method is capable of identifying the mass, damping and restoring force of a frame structure, which can be used in forming the equations of motion of the frame. By solving the equations of motion, the dynamic response is predicted. The method is based on the combined using of the Quadratic Programming (QP) and Genetic Algorithms (GA). First, assuming a set of Prandtl-Ishlinskii constants, the QP is used to find the best frame...
Experiments on turbidity current regimes in a straight open channel
, Article World Environmental and Water Resources Congress 2011: Bearing Knowledge for Sustainability - Proceedings of the 2011 World Environmental and Water Resources Congress, 22 May 2011 through 26 May 2011 ; May , 2011 , Pages 4047-4064 ; 9780784411735 (ISBN) ; Ayyoubzadeh, S. A ; Firoozabadi, B ; Kordi, E ; Sharif University of Technology
2011
Abstract
The present study has been conducted to investigate the effect of inlet flow regimes on vertical velocity and concentration profiles of the turbidity current. Experiments carried out on small scale channel and Kaolin with a density of 2.65 kg/m3 and a mean particle diameter of 4.5 μm, was used to generate the currents. Velocities were obtained at a rate of 10 Hz using an acoustic Doppler velocimeter. Using the siphon sampling approach, the acoustic backscattering intensity was calibrated and concentration was determined using a backscattering analysis. Results showed that the ratio of maximum velocity height to the height of the current was around 0.4-0.5 in sub- and super-critical regimes....
Nonlinear dynamic modeling of surface defects in rolling element bearing systems
, Article Journal of Sound and Vibration ; Volume 319, Issue 3-5 , 2009 , Pages 1150-1174 ; 0022460X (ISSN) ; Abbasion, S ; Farshidianfar, A ; Moeenfard, H ; Sharif University of Technology
2009
Abstract
In this paper an analytical model is proposed to study the nonlinear dynamic behavior of rolling element bearing systems including surface defects. Various surface defects due to local imperfections on raceways and rolling elements are introduced to the proposed model. The contact force of each rolling element described according to nonlinear Hertzian contact deformation and the effect of internal radial clearance has been taken into account. Mathematical expressions were derived for inner race, outer race and rolling element local defects. To overcome the strong nonlinearity of the governing equations of motion, a modified Newmark time integration technique was used to solve the equations...
Supersonic flutter prediction of functionally graded conical shells
, Article Composite Structures ; Volume 92, Issue 2 , 2010 , Pages 377-386 ; 02638223 (ISSN) ; Haddadpour, H ; Navazi, H.M ; Sharif University of Technology
2010
Abstract
Aero-thermoelastic analysis of a simply supported functionally graded truncated conical shell subjected to supersonic air flow is performed to predict the flutter boundaries. The temperature-dependent properties of the FG shell are assumed to be graded through the thickness according to a simple rule of mixture and power-law function of volume fractions of material constituents. Through the thickness steady-state heat conduction is considered for thermal analysis. To perform the stability analysis, the general nonlinear equations of motion are first derived using the classical Love's shell theory and the von Karman-Donnell-type of kinematic nonlinearity together with the linearized...