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Total 22 records

    Oblique rectangular sharp-crested weir

    , Article Proceedings of the Institution of Civil Engineers: Water and Maritime Engineering ; Volume 156, Issue 2 , 2003 , Pages 185-191 ; 14724561 (ISSN) Borghei, S. M ; Vatannia, Z ; Ghodsian, M ; Jalili, M. R ; Sharif University of Technology
    ICE Publishing  2003
    Abstract
    Among discharge flowmeters, the rectangular sharp-crested weir is one of the most popular and accurate, as well as being easy to work with. Using the standard weir, with the help of the conventional weir equation and Rehbock's or a similar standard formula for the discharge coefficient (Cd), the flow can be easily calculated. In order to increase the efficiency of the weir, it can be placed obliquely to the flow, increasing the effective weir length (L) and, hence, increasing the discharge for the same water head with the same channel width (B). The results of a comprehensive set of tests for oblique weirs (1·14 ≤ L/B ≤ 2·26 or oblique angles from 29° to 64°) show that for L/B less than 1·41... 

    Hydraulic performance of labyrinth side weirs using vanes or piles

    , Article Proceedings of the Institution of Civil Engineers: Water Management ; Volume 164, Issue 5 , 2011 , Pages 229-241 ; 17417589 (ISSN) Kabiri Samani, A ; Borghei, S. M ; Esmaili, H ; Sharif University of Technology
    Abstract
    In the present study, methods for improving the hydraulic performance of labyrinth side weirs in a rectangular channel are reported based on model experimentation. For this purpose different arrangements and configurations of groups of guide vane plates and piles in the side weir flow field were tested. Experiments were conducted on labyrinth side weirs of different lengths and sill heights fitted in the test section of a rectangular glass-walled channel. Depths of flow were measured in both longitudinal and crosswise directions at regular intervals and their profiles were studied. It was found that the discharge coefficient of the labyrinth side weirs under these conditions gave... 

    Hydrodynamics Modeling and Self Orginizing Control of Marine Vehicles

    , M.Sc. Thesis Sharif University of Technology Taghi, Amir Hossein (Author) ; Sayyadi, Hassan (Supervisor)
    Abstract
    Dynamic positioning system is a controller system used to maintain the position and heading of a vessel with no use of anchors, jack ups but only using the propellers installed on the vessel. A vessel has six degrees of freedom, including three rotations and three transfer. In dynamic positioning systems, the vessel is controlled only on the horizontal plane such that its position and heading are controlled according to predetermined values. To achieve this, position and heading of the vessel is determined and the controller system computes the direction and required power of each propeller. Preliminary systems utilized PID controllers. As the control science has advanced, model based... 

    Modeling Paramecium swimming in a capillary tube

    , Article Scientia Iranica ; Volume 23, Issue 2 , 2016 , Pages 658-667 ; 10263098 (ISSN) Sarvestani, A. N ; Shamloo, A ; Ahmadian, M. T ; Sharif University of Technology
    Sharif University of Technology 
    Abstract
    In certain types of biomimetic surgery systems, micro robots inspired by Paramecium are designed to swim in a capillary tube for gaining access to internal organs with minimal invasion. Gaining insight into the mechanics of Paramecium swimming in a capillary tube is vital for optimizing the design of such systems. There are two approaches to modeling the physics of micro swimming. In the envelope approach, which is widely accepted by researchers, Paramecium is approximated as a sphere, self-propelled by tangential and normal surface distortions. However, not only is this approach incapable of considering the specific geometry of Paramecium, but it also neglects short range hydrodynamic... 

    Optimizing the Propulsion Arrangement of a Par Wig Craft to Reduce the Take-off Time

    , M.Sc. Thesis Sharif University of Technology Mafakher, Mohammad Reza (Author) ; Seif, Mohamad Saeed (Supervisor)
    Abstract
    In this thesis, an attempt is made to provide a hydro-aerodynamic mathematical model of a 20-bird batboat with a combined wing with catamaran body shape equipped with a parachute propulsion system in the rising phase of the surface and optimizing the propulsion system to reduce the take-off phase of the bird's boat. For this purpose, the hydro-aerodynamic modeling of the bird's boat from the rest period to the cruise phase has been considered, taking into account the parachuting system. For this purpose, three methods are considered. In the first method, combinatorial wing aerodynamic modeling and hydrodynamic modeling of the radar catamaran float were first studied. Finally, in the case of... 

    Design and Fabrication of a Swimmer Robot at Low Reynolds Number

    , Ph.D. Dissertation Sharif University of Technology Bahmanyar, Shahnaz (Author) ; Sayyadi, Hassan (Supervisor)
    Abstract
    Helical swimming robots with a capable propulsion system at low Reynolds numbers have been proposed for many applications. Although linear propulsion characteristics of swimming robots with a single helical flagellum have been extensively studied, the characteristics of maneuverability have not been completely investigated yet. In this thesis two novel mechanisms was proposed. The first mechanism presents a new method for the maneuverability of the helical swimming robot with a single helical flagellum. This mechanism is based on the change in the angle between the helical and body axes. This study shows that a change in the aforementioned angle can enable the swimming robot to have turning... 

    Modeling and Simulation of the Catalyst Regeneration Process of FCC Unit of Abadan Refinery

    , M.Sc. Thesis Sharif University of Technology Loni, Zahra (Author) ; Baghalha, Morteza (Supervisor)
    Abstract
    Hydrodynamics plays a crucial role in defining the performance of fluidized beds. The numerical simulation of fluidized bed is very important in the prediction of its behaviour. From this point of view, in the present study a dynamic two dimensioanl model is developed for the modeling of regenerator system of a UOP fluid catalytic cracking (FCC) unit of Abadan refinery with a high-efficiency regenerator. Of the various modeling and simulation techniques, computational fluid dynamics (CFD) is employed in this thesis. Effects of gas velocity, the transient local solid volume fraction, pressure drop for gas and solid phase, solid holdup distribution and solid circulation pattern have been... 

    Development of a Three-Dimensional Numerical Hydrodynamic Model of Lake Urmia Using Satellite Data Integration, Field Data, and Data Assimilation

    , M.Sc. Thesis Sharif University of Technology Jamaat, Amir Moez (Author) ; Safaie Nematabadi, Ammar (Supervisor)
    Abstract
    The aim of this research is to use data assimilation in hydrodynamic modeling of Lake Urmia, which is known as one of the world's hypersaline lakes. In other words, it is the first time that the development of a numerical model for Lake Urmia has been accompanied by data assimilation. In recent years, Lake Urmia has experienced unfavorable climatic conditions, resulting in a decline of over 8 meters in its water level over the past 20 years. Hydrodynamic analysis of the lake can play a crucial role in major management decisions for restoration of the lake ecosystem. In this project, the three-dimensional FVCOM model was used to perform numerical modeling, and efforts were made to improve... 

    Development of an Improved Wet/Drying Algorithm for Hydrodynamic Models to Ppredict Water Salinity in a Hypersaline Lake: the case of Lake Urmia

    , M.Sc. Thesis Sharif University of Technology Zarei Beydokhty, Alireza (Author) ; Safaie, Ammar (Supervisor)
    Abstract
    Considering the significant impact of salinity and temperature on the life of aquatic ecosystems, the growth of plants and animals, and the health of people; it is necessary to predict the spatiotemporal distribution of these qualitative characteristics in aquatic environments by using precise algorithms through hydrodynamic models. This research presents an improved algorithm for calculating qualitative characteristics of aquatic environments, such as salinity, during the wet/drying processes. The developed algorithm in this study has been incorporated into FVCOM which is a three-dimensional hydrodynamic model. The current algorithm governing the FVCOM model is not capable of accurately... 

    Mathematical modeling of a slurry bubble column reactor for hydrodesulfurization of diesel fuel: Single- and two-bubble configurations

    , Article Chemical Engineering Research and Design ; Volume 100 , August , 2015 , Pages 362-376 ; 02638762 (ISSN) Khadem Hamedani, B ; Yaghmaei, S ; Fattahi, M ; Mashayekhan, S ; Hosseini Ardali, S. M ; Sharif University of Technology
    Institution of Chemical Engineers  2015
    Abstract
    In this investigation, a mathematical model for HDS of diesel fuel in a slurry bubble column reactor was developed. The model is based on the axial dispersion of the heterogeneous gas flow regime, which includes two various bubble classes: large (20±70mm) and small (1±10mm). By assuming only large or large plus small bubbles in the column, single- and two-bubble class mode equations are developed. The developed models to solving the mass and enthalpy balances from which the sulfur conversion was obtained that undertaken. The chemical kinetics over NiMoS/γ-Al2O3 catalyst were undertaken for the reaction rate of the involved reactions. The reactor operating conditions... 

    On the design of robotic fish based on lighthill's small-amplitude elongated body theory

    , Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 11 , 2009 , Pages 119-125 ; 9780791848722 (ISBN) Shahi, M ; Meghdari, A ; Sharif University of Technology
    2009
    Abstract
    This paper addresses the issues of energy efficiency in robotic fish design by use of hydrodynamic models. The use of LighthilPs small-amplitude elongated body theory for designing of robotic fish, obtaining optimal kinematics and dynamic analysis with emphasis on compliant mechanism is presented. Simulation results for a sample case have demonstrated the importance of proposed approach in robotic fish design. Copyright © 2008 by ASME  

    Hydrodynamics maneuver of a single helical flagellum swimming robot at low-Reynolds condition

    , Article Microfluidics and Nanofluidics ; Volume 23, Issue 1 , 2019 ; 16134982 (ISSN) Sayyaadi, H ; Bahmanyar, S ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    Helical swimming robots with a capable propulsion system at low-Reynolds numbers have been proposed for many applications. Although linear propulsion characteristics of swimming robots with a single helical flagellum have been extensively studied, the characteristics of maneuverability have not been completely investigated yet. This study presents a new method for the maneuverability of the helical swimming robot with a single helical flagellum. This mechanism is based on the change in the angle between the helical and body axes. This study shows that a change in the aforementioned angle can enable the swimming robot to have turning maneuvers in clockwise or counterclockwise directions.... 

    Hydrodynamics maneuver of a single helical flagellum swimming robot at low-reynolds condition

    , Article Microfluidics and Nanofluidics ; Volume 23, Issue 1 , 2019 ; 16134982 (ISSN) Sayyaadi, H ; Bahmanyar, S ; Sharif University of Technology
    Springer Verlag  2019
    Abstract
    Helical swimming robots with a capable propulsion system at low-Reynolds numbers have been proposed for many applications. Although linear propulsion characteristics of swimming robots with a single helical flagellum have been extensively studied, the characteristics of maneuverability have not been completely investigated yet. This study presents a new method for the maneuverability of the helical swimming robot with a single helical flagellum. This mechanism is based on the change in the angle between the helical and body axes. This study shows that a change in the aforementioned angle can enable the swimming robot to have turning maneuvers in clockwise or counterclockwise directions.... 

    Assessment of 2DH and pseudo-3D modelling platforms in a large saline aquatic system: Lake Urmia, Iran

    , Article Hydrological Processes ; Vol. 28, Issue. 18 , 2014 , pp. 49534970 ; ISSN: 10991085 Zeinoddini, M ; Tofighi, M. A ; Bakhtiari, A ; Sharif University of Technology
    Abstract
    The main objective of this paper is to provide comparative quantitative examinations on the capabilities of two-dimensional horizontal and pseudo-three-dimensional (3D) modelling approaches for simulating spatial and temporal variability of the flow and salinity in Lake Urmia, Iran. The water quality in the lake has been an environmentally important subject partly because this shallow hypersaline aquatic ecosystem is considered to be one of the largest natural habitats of a unique multicellular organism, Artemia urmiana. This brine shrimp is the major food source for many of the protected and rare shorebirds that visit the lake. A.urmiana can grow and survive in certain ranges of salinity,... 

    A systematic method for the complex walls no-slip boundary condition modeling in dissipative particle dynamics

    , Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1253-1260 ; 10263098 (ISSN) Mehboudi, A ; Saidi, M. S ; Sharif University of Technology
    2011
    Abstract
    The dissipative particle dynamics method is an efficient method for studying the hydrodynamics of complex fluids. One of the most challenging aspects of this method appears when the solid walls exist. The solid walls disturb the homogeneity of the fluid near the wall and cause some spurious fluctuations. Thus, in recent years a large amount of effort has been devoted to solve this shortcoming. Fortunately the mentioned problem has almost been solved for the simple walls such as flat walls, circular cylinders, spheres, etc. However no systematic model has addressed the complex walls. It should be noted that almost all of the walls we deal with in practical problems such as MEMS devices,... 

    Cooperation within von Willebrand factors enhances adsorption mechanism

    , Article Journal of the Royal Society Interface ; Volume 12, Issue 109 , 2015 ; 17425689 (ISSN) Heidari, M ; Mehrbod, M ; Ejtehadi, M. R ; Mofrad, M. R ; Sharif University of Technology
    Royal Society of London  2015
    Abstract
    von Willebrand factor (VWF) is a naturally collapsed protein that participates in primary haemostasis and coagulation events. The clotting process is triggered by the adsorption and conformational changes of the plasma VWFs localized to the collagen fibres found near the site of injury. We develop coarse-grained models to simulate the adsorption dynamics of VWF flowing near the adhesive collagen fibres at different shear rates and investigate the effect of factors such as interaction and cooperativity of VWFs on the success of adsorption events. The adsorption probability of a flowing VWF confined to the receptor field is enhanced when it encounters an adhered VWF in proximity to the... 

    Positioning and tracking control of an amphibious single wheel robot

    , Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 11 , 2009 , Pages 545-551 ; 9780791848722 (ISBN) Marzban, M ; Alizadeh, D ; Sharif University of Technology
    2009
    Abstract
    Amphibious single wheel robot consists of a sharp-edged wheel actuated by a spinning flywheel for steering and a drive motor for propulsion. The spinning flywheel acts as a gyroscope to stabilize the robot and also can be tilted to achieve steering. In this paper, the kinematics of a single wheel robot in water, Gyrover, is analyzed and then a simple mechanism for driving it is proposed. In previous studies, Lagrange approach is used for hydrodynamic modeling of the robot. A nonlinear position controller is designed to bring the robot to any desired position. Based on the designed controller, a tracking controller is augmented to the robot. For simplicity the added mass effect has been... 

    A new method in two phase flow modeling of a non-uniform grid

    , Article Scientia Iranica ; Volume 16, Issue 5 B , 2009 , Pages 425-439 ; 10263098 (ISSN) Bohluly, A ; Borghei, M ; Saidi, M. H ; Sharif University of Technology
    2009
    Abstract
    In this paper, a two dimensional numerical model for two phase flow is presented. For interface tracking, the FGVT-VOF (Fine Grid Volume Tracking-Volume Of Fluid) method is selected. For momentum advection, an improved approach is used. In this scheme, a volume tracking step is coupled with steps of computations for the advection of momentum. A Reynolds stress algebraic equation has been implemented in the algorithm of turbulent modeling. Standard test cases are used for the verification of interface tracking and hydrodynamic modeling in laminar and turbulent conditions. The test results show that this methodology can be used in different applications of two-phase flow modeling. © Sharif... 

    An efficient system identification approach to estimate unsteady loads on cavitator plates

    , Article Ocean Engineering ; Volume 207 , 2020 Tehrani, M. A ; Dehghani Firouz Abadi, R ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    A new and efficient model for calculation of the unsteady hydrodynamic loads on an oscillating plate in two-dimensional flow is proposed. In order to compute the hydrodynamic loads, an unsteady hydrodynamic model is derived using the boundary-element method along with the potential flow assumption. To this aim, the steady boundary of cavity is determined by a full-nonlinear iterative procedure. Thereafter, assuming that amplitude and frequency of oscillations are so that the length of cavity in unsteady flow remains intact, simulation of the unsteady hydrodynamic flow is performed by imposing some velocity perturbations over the steady cavity solutions. Consequently, based on this... 

    Thermo-hydrodynamic modeling of a single bubble nozzle-diffuser phase change micropump

    , Article 6th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2008, Darmstadt, 23 June 2008 through 25 June 2008 ; Issue PART B , June , 2008 , Pages 1237-1243 ; 0791848345 (ISBN); 9780791848340 (ISBN) Saidi, M. S ; Saeedi, M. H ; Pirouzpanah, S ; Nikparto, A ; ASME ; Sharif University of Technology
    2008
    Abstract
    Nowadays, the potential of phase change process in liquids at micro scale attracts the scientists to fabricate this type of micropumps. Such micropumps have widely found applications in industrial and medical equipments such as recent printers. Not using mechanical parts such as valves, and having small sizes and high and controllable mass flow rates are the advantages of these micropumps. In the nozzle diffuser phase change micropump a heat pulse generates a bubble in a chamber; therefore, the pressure pulse which is generated by the bubble, causes the bubble to expand suddenly with high rate, then the pressure of bubble reduces to the vapor pressure and causes negative rate of expansion to...