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flow-modeling
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Analytical study of fluid flow modeling by diffusivity equation including the quadratic pressure gradient term
, Article Computers and Geotechnics ; Volume 89 , 2017 , Pages 1-8 ; 0266352X (ISSN) ; Izadmehr, M ; Karimi, M ; Sharifi, M ; Kazemi, A ; Sharif University of Technology
Abstract
Diffusivity equation which can provide us with the pressure distribution, is a Partial Differential Equation (PDE) describing fluid flow in porous media. The quadratic pressure gradient term in the diffusivity equation is nearly neglected in hydrology and petroleum engineering problems such as well test analysis. When a compressible liquid is injected into a well at high pressure gradient or when the reservoir possess a small permeability value, the effect of ignoring this term increases. In such cases, neglecting this parameter can result in high errors. Previous models basically focused on numerical and semi-analytical methods for semi-infinite domain. To the best of our knowledge, no...
Iran atlas of offshore renewable energies
, Article Renewable Energy ; Volume 36, Issue 1 , January , 2011 , Pages 388-398 ; 09601481 (ISSN) ; Rahimi, R ; Sharif University of Technology
2011
Abstract
The aim of the present study is to provide an Atlas of IRAN Offshore Renewable Energy Resources (hereafter called 'the Atlas') to map out wave and tidal resources at a national scale, extending over the area of the Persian Gulf and Sea of Oman. Such an Atlas can provide necessary tools to identify the areas with greatest resource potential and within reach of present technology development. To estimate available tidal energy resources at the site, a two-dimensional tidally driven hydrodynamic numerical model of Persian Gulf was developed using the hydrodynamic model in the MIKE 21 Flow Model (MIKE 21HD), with validation using tidal elevation measurements and tidal stream diamonds from...
Impact of swimming gyrotactic microorganisms and viscous dissipation on nanoparticles flow through a permeable medium: a numerical assessment
, Article Journal of Nanomaterials ; Volume 2022 , 2022 ; 16874110 (ISSN) ; Younis, J ; Ali, K ; Rizwan, M ; Ashraf, M ; Abd El Salam, M. A ; Sharif University of Technology
Hindawi Limited
2022
Abstract
In this paper, heat and mass transportation flow of swimming gyrotactic microorganisms (microbes) and solid nanoparticles under the viscous dissipation effect is investigated. The flow model PDEs are renovated with ordinary ones using suitable boundary layer approximations. The system governing the flow model dimensionless equations as well as boundary conditions is numerically treated with the SOR (successive over relaxation) technique. The flow, heat, and mass transport characteristics are examined against the prime parameters. A comparison is examined to be in a good agreement with the earlier results. It is found here that flow and thermal characteristics of the problem are substantially...
Effects of microhydrophobic porous layer on water distribution in polymer electrolyte membrane fuel cells
, Article Journal of Fuel Cell Science and Technology ; Vol. 11, Issue. 1 , 2014 ; ISSN: 1550-624X ; Roshandel, R ; Sharif University of Technology
Abstract
Performance of polymer electrolyte membrane fuel cells (PEMFC) at high current densities is limited to transport reactants and products. Furthermore, large amounts of water are generated and may be condensed due to the low temperature of the PEMFC. Development of a two-phase flow model is necessary in order to predict water flooding and its effects on the PEMFC performance. In this paper, a multiphase mixture model (M2) is used, accurately, to model two-phase transport in porous media of a PEMFC. The cathode side, which includes channel, gas diffusion layer (GDL), microporous layer (MPL), and catalyst layer (CL), is considered as the computational domain. A multidomain approach has been used...
Simulation of red blood cell motion in microvessels using modified moving particle semi-implicit method
, Article Scientia Iranica ; Volume 19, Issue 1 , 2012 , Pages 113-118 ; 10263098 (ISSN) ; Firoozbakhsh, K ; Hasanian, M ; Sharif University of Technology
Abstract
Red Blood Cells (RBCs) are the main cells in human blood, with a main role in the mechanical properties of blood as a fluid. Several methods have been improved to simulate the mechanical behavior of RBC in micro-capillaries. Since, in microscopic scales, using discrete models is more preferred than continuum methods, the Moving Particle Semi-Implicit method (MPS), which is a recent innovative particle based method, can simulate micro-fluidic flows based on NavierStokes equations. Although, by recent developments, the MPS method has turned into a considerable tool for modeling blood flow in micro meter dimensions, some problems, such as a commitment to use small time step sizes, still...
Unsteady RANS simulation of a surface piercing propeller in oblique flow
, Article Applied Ocean Research ; Volume 56 , 2016 , Pages 79-91 ; 01411187 (ISSN) ; Zabihzade Roshan, S ; Seif, M. S ; Sharif University of Technology
Elsevier Ltd
Abstract
Conventional propellers might undergo severe cavitation at high speeds and this phenomenon not only affects the efficiency of the propeller, but also may result in serious damages in propulsion system. Due to their special geometries, surface piercing propellers (SPPs) overcome this problem and achieve high efficiencies in high speeds. Therefore, SPPs are one of the popular propulsors for high-speed crafts. The present research is aimed to pursue SPP's performance in the off-design conditions. URANS method was used to study the performance of the 841-SPP (case with some available experimental results; Olofsson, 1996) in several immersion ratios (= 33%, 50%, 75% and 100%) and maneuvering...
Using vorticity as an indicator for the generation of optimal coarse grid distribution
, Article Transport in Porous Media ; Volume 75, Issue 2 , 2008 , Pages 167-201 ; 01693913 (ISSN) ; Firoozabadi, B ; Mahani, H ; Sharif University of Technology
2008
Abstract
An improved vorticity-based gridding technique is presented and applied to create optimal non-uniform Cartesian coarse grid for numerical simulation of two-phase flow. The optimal coarse grid distribution (OCGD) is obtained in a manner to capture variations in both permeability and fluid velocity of the fine grid using a single physical quantity called "vorticity". Only single-phase flow simulation on the fine grid is required to extract the vorticity. Based on the fine-scale vorticity information, several coarse grid models are generated for a given fine grid model. Then the vorticity map preservation error is used to predict how well each coarse grid model reproduces the fine-scale...
Effect of operating conditions on the performance of a PEM fuel cell
, Article International Journal of Heat and Mass Transfer ; Volume 144 , 2019 ; 00179310 (ISSN) ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In this study, a two-phase flow model based on species transport, energy, and electrochemical equations was developed for polymer electrolyte membrane fuel cell (PEMFC). The influences of heat sources and sinks, and water transport inside the fuel cell were also taken into account. In this regard, the effect of the operating conditions including cell temperature and pressure, anode and cathode inlet humidity, and anode and cathode stoichiometric ratios on the fuel cell performance was investigated. The simulation results show that inlet humidity and stoichiometric ratio of the anode side, cell pressure and temperature, and distribution of the heat sources and sinks are crucial factors...
Simulation of turbulent flow through porous media employing a v2f model
, Article Scientia Iranica ; Volume 16, Issue 2 B , 2009 , Pages 159-167 ; 10263098 (ISSN) ; Kazemzadeh Hannani, S ; Sharif University of Technology
2009
Abstract
In this article, a v2f model is employed to conduct a series of computations of incompressible flow in a periodic array of square cylinders simulating a porous media. A Galerkin/least-squares finite element formulation employing equal order velocity-pressure elements is used to discretize the governing equations. The Reynolds number is varied from 1000 to 84,000 and different values of porosities are considered in the calculations. Results are compared to the available data in the literature. The v2f model exhibits superior accuracy with respect to κ - ε results and is closer to LES calculations. The macroscopic pressure gradients for all porosities studied showed a good agreement with...
Prediction of downhole flow regimes in deviated horizontal wells for production log interpretation
, Article Society of Petroleum Engineers - Trinidad and Tobago Energy Resources Conference 2010, SPE TT 2010, 27 June 2010 through 30 June 2010 ; Volume 2 , June , 2010 , Pages 525-530 ; 9781617388859 (ISBN) ; Hosseinian, A ; Rasouli, V ; Siavoshi, J ; Mirabolghasemi, M ; Sinanan, B ; Bagherian, B ; Sharif University of Technology
2010
Abstract
Production logging is used to evaluate wells production performance. Interpretation of production log data provides velocity profile and contribution of each zone on total production. In multi-phase flow conditions, production log interpretation can be challenging since producing fluids do not have similar densities and travel with different speed depending on fluids properties and wellbore deviation. Production log interpretation in multi-phase producing wells requires identifying downhole flow regimes and determining velocity profile for each phase. There are different flow regimes and velocity models available, which are being used in production log interpretation to determine wells flow...
Predictive functional control for active queue management in congested TCP/IP networks
, Article ISA Transactions ; Volume 48, Issue 1 , 2009 , Pages 107-121 ; 00190578 (ISSN) ; Haeri, M ; Sharif University of Technology
2009
Abstract
Predictive functional control (PFC) as a new active queue management (AQM) method in dynamic TCP networks supporting explicit congestion notification (ECN) is proposed. The ability of the controller in handling system delay along with its simplicity and low computational load makes PFC a privileged AQM method in the high speed networks. Besides, considering the disturbance term (which represents model/process mismatches, external disturbances, and existing noise) in the control formulation adds some level of robustness into the PFC-AQM controller. This is an important and desired property in the control of dynamically-varying computer networks. In this paper, the controller is designed based...
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) ; 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...
Influence of unsteady flow hydrograph shape on local scouring around bridge pier
, Article Proceedings of the Institution of Civil Engineers: Water Management ; Volume 165, Issue 9 , October , 2012 , Pages 473-480 ; 17417589 (ISSN) ; Kabiri-Samani, A ; Banihashem, S. A ; Sharif University of Technology
ICE Pub
2012
Abstract
Accurate estimation of scour depth is needed for economic and safe determination of bridge pier foundation depth. Most design criteria are based on maximum scour depth due to the steady design discharge without flow time limit. In this paper, the results are presented of an experimental investigation on local scouring around a single bridge pier under steady and unsteady flow regimes. For unsteady flow, triangular shape hydrographs with repeatable peaks have been chosen. Results show that both sharp and flat increases to the peak of hydrographs have a negligible effect on scour depth for the same base time. An equation is obtained to compute the scour depth due to a specific triangular...
Simulation of rarefied micro to nano gas flows using improved slip flow models
, Article 37th AIAA Fluid Dynamics Conference, Miami, FL, 25 June 2007 through 28 June 2007 ; Volume 1 , 2007 , Pages 576-583 ; 1563478978 (ISBN); 9781563478970 (ISBN) ; Rikhtegar, F ; Schneider, G. E ; Sharif University of Technology
2007
Abstract
If the hydrodynamic diameter of a channel is comparable with the mean free path of the gas molecules moving inside the channel, the fluid can no longer be considered to be in thermodynamic equilibrium and a variety of non-continuum or rarefaction effects can occur. To avoid enormous complexity and extensive numerical cost encountered in modeling of nonlinear Boltzmann equations, the Navier-Stokes equations can be solved considering the concepts of slip flow regime and applying slip velocity boundary conditions at the solid walls. The high-order slip models can, in some cases, extend the range of applicability of the Navier-Stokes equations beyond Kn = 0.1, where the accuracy of first-order...
The unsteady behavior of subsonic wind tunnel wall pressure during pitching motion of the model
, Article Scientia Iranica ; Vol.21, issue.1 , 2014 , p. 192-202 ; 10263098 ; Soltani, M. R ; Ghaeminasab, M ; Sharif University of Technology
Abstract
Extensive low speed wind tunnel experiments have been undertaken to measure the test section, oor wall pressure distribution, in the presence of a 2D wing inside the test section. The experiments were performed for both the static and dynamic pitching motion of the model under difierent conditions. In these measurements, the efiects of the existence and oscillations of a 2D wing on the oor wall pressure at various locations were studied. According to the results, as the oscillation parameters, such as mean angle of attack and frequency, change, wall pressures at the points located in the front part of the test section, in the upstream region, exhibit difierent behavior from those in the...
Optimal distributed static series compensator placement for enhancing power system loadability and reliability
, Article IET Generation, Transmission and Distribution ; Volume 9, Issue 11 , 2015 , Pages 1043-1050 ; 17518687 (ISSN) ; Fotuhi Firuzabad, M ; Aminifar, F ; Safdarian, A ; Lehtonen, M ; Sharif University of Technology
Institution of Engineering and Technology
2015
Abstract
Distributed static series compensator (DSSC) is a member of the family of distributed flexible AC transmission system devices that can be attached directly to conductors of transmission lines. DSSCs are able to compensate for and adjust the line reactance; thus, they could be widely used in stability-limited transmission systems. Owing to economic matters, the optimal placement of DSSCs is of a great interest from practical viewpoints. This study presents an approach to find the optimal locations of DSSCs to enhance the system loadability and reliability using the DC load flow model. The optimisation problem is solved using the mixed-integer linear programming. A compromise between improving...
Experimental and modelling study of gravity drainage in a three-block system
, Article Transport in Porous Media ; Volume 136, Issue 2 , 2021 , Pages 471-494 ; 01693913 (ISSN) ; Karimi Malekabadi, A ; Ghazanfari, M. H ; Rostami, B ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
Gravity drainage is known as the controlling mechanism of oil recovery in naturally fractured reservoirs. The efficiency of this mechanism is controlled by block-to-block interactions through capillary continuity and/or reinfiltration processes. In this study, at first, several free-fall gravity drainage experiments were conducted on a well-designed three-block apparatus and the role of tilt angle, spacers’ permeability, wettability and effective contact area (representing a different status of the block-to-block interactions between matrix blocks) on the recovery efficiency were investigated. Then, an experimental-based numerical model of free-fall gravity drainage process was developed,...
Non-Newtonian fluid flow dynamics in rotating annular media: Physics-based and data-driven modeling
, Article Journal of Petroleum Science and Engineering ; Volume 185 , 2020 ; Amooie, M. A ; Shams, R ; Hajirezaie, S ; Liu, Y ; Jamshidi, S ; Soltanian, M. R ; Sharif University of Technology
Elsevier B.V
2020
Abstract
A thorough understanding and accurate prediction of non-Newtonian fluid flow dynamics in rotating annular media are of paramount importance to numerous engineering applications. This is in particular relevant to oil and gas industry where this type of flow could occur during, e.g., drilling, well completion, and enhanced oil recovery scenarios. Here, mathematically we report on physical-based (numerical) and data-driven (intelligent) modeling of three-dimensional laminar flow of non-Newtonian fluids driven by axial pressure gradient in annular media that consist of a coaxially rotating inner cylinder. We focus on the dynamics of pressure loss ratio (PLR)—the ratio of total pressure loss in...
Effect of active feather length on aerodynamic performance of airfoils at low reynolds number flow
, Article AIAA AVIATION 2020 FORUM, 15 June 2020 through 19 June 2020 ; Volume 1 PartF , 2020 ; Darbandi, M ; Schneider, G. E ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc, AIAA
2020
Abstract
To increase the flight endurance of a Micro air vehicle (MAVs), which operates at low Reynolds number flow, one way is to harvest energy during its flight. By inspiring from the nature when all the birds use their feathers to control and distribute their power along the flying time, a solution might be design of a piezoelectric plate as feathers, which scavenges energy directly from the fluid flow. Cantilevered beam with piezo-ceramic layer undergoing vortex-induced vibrations can convert the mechanical energy available from the ambient environment to a usable electrical power. Since a flow-driven piezoelectric composite beam takes a form of natural three-way coupling of the turbulent fluid...
Theoretical comparative assessment of single- and two-phase models for natural convection heat transfer of Fe3O4/ethylene glycol nanofluid in the presence of electric field
, Article Journal of Thermal Analysis and Calorimetry ; 2020 ; Tavakoli, S ; Pishvaie, M. R ; Sharif University of Technology
Springer Netherlands
2020
Abstract
Natural convective heat transfer of Fe3O4/ethylene glycol nanofluids around the platinum wire as a heater in the absence and presence of the high electric field was investigated, numerically. The control volume finite element method was employed for the numerical simulation. Effects of the flow model, the volume fraction of nanoparticles, Rayleigh number, and the electric field intensity on the natural heat transfer coefficient (NHTC) of nanofluid were studied. Simulation results of single-phase and two-phase flow models showed that the two-phase model could better predict experimental data than the single-phase model due to take into account the velocity of each phase in the mixture. The...