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hydraulics
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3D simulation of propagation of hydraulically driven fractures in oil reservoirs using EFG mesh-less method considering coupled hydro-mechanical effects
, Article Computer Methods and Recent Advances in Geomechanics - Proceedings of the 14th Int. Conference of International Association for Computer Methods and Recent Advances in Geomechanics, IACMAG 2014, 22 September 2014 through 25 September 2014, Kyoto ; September , 2015 , Pages 1675-1680 ; 9781138001480 (ISBN) ; Samimi, S ; Sharif University of Technology
Taylor and Francis - Balkema
2015
Abstract
Creating hydraulically induced fractures in oil/gas reservoirs is one of the methods for Enhanced Oil Recovery (EOR) that has been applied extensively in petroleum industry in recent years. Despite its popularity, the design process of Hydraulic Fracture treatment is mostly empirical based on the previous experiences gained in the oil-rich formation. The reason lies in the complexities involved in the Hydraulic Fracture process including interacting effects of fluid(s) flowand solid deformations, injection of non-Newtonian fluids in the porous media, leak-off of the injected fluid into the formation, complex geometry of the induced fracture in the intact or naturally fractured rock,...
A comprehensive study on the critical ventilation velocity in tunnels with different geometries
, Article International Journal of Ventilation ; Volume 14, Issue 3 , Mar , 2015 , Pages 303-320 ; 14733315 (ISSN) ; Afshin, H ; Farhanieh, B ; Sharif University of Technology
VEETECH Ltd
2015
Abstract
Longitudinal ventilation is a common technique for smoke management during a fire accident within tunnels. In this paper, fire and smoke movement behaviour in longitudinally ventilated tunnels is investigated focusing on critical ventilation velocity. Firstly, critical velocity (VC) is evaluated for different heat release rates and results are compared and verified with model scale experimental data. Secondly, two fire scenarios inside tunnels with different cross sections are arranged and the reliability of some existing correlations for VC is explored. Results illustrate that using a combined geometric scale rather than the traditional single length-scale ones results in better estimation...
A correlated fracture network: modeling and percolation properties
, Article Water Resources Research ; Volume 43, Issue 7 , 2007 ; 00431397 (ISSN) ; King, P. R ; Sharif University of Technology
2007
Abstract
We present a model of fractures based on the idea that the elastic free energy due to the fracture density follows a Boltzmann distribution. The resulting expression for the spatial correlation in the displacement of fractures is used as an objective function in a simulated annealing algorithm to generate realizations of correlated fracture networks. This approach determines the appropriate statistical distribution for the fractures (e.g., length distribution) rather than imposing them as is done conventionally. The model consists of two families of parallel fractures which are perpendicular under isotropic conditions. There also exists a positive correlation between the position of...
A coupled hydro-mechanical analysis for prediction of hydraulic fracture propagation in saturated porous media using EFG mesh-less method
, Article Computers and Geotechnics ; Vol. 55, issue , January , 2014 , p. 254-266 ; Pak, A ; Soga, K ; Sharif University of Technology
Abstract
The details of the Element Free Galerkin (EFG) method are presented with the method being applied to a study on hydraulic fracturing initiation and propagation process in a saturated porous medium using coupled hydro-mechanical numerical modelling. In this EFG method, interpolation (approximation) is based on nodes without using elements and hence an arbitrary discrete fracture path can be modelled.The numerical approach is based upon solving two governing partial differential equations of equilibrium and continuity of pore water simultaneously. Displacement increment and pore water pressure increment are discretized using the same EFG shape functions. An incremental constrained Galerkin...
A coupled wellbore-reservoir flowmodel for numerical pressure transient analysis in vertically heterogeneous reservoirs
, Article Journal of Porous Media ; Volume 16, Issue 5 , 2013 , Pages 395-400 ; 1091028X (ISSN) ; Soltanieh, M ; Farhadpour, F. A ; Sharif University of Technology
2013
Abstract
Pressure transient analysis in vertically heterogeneous reservoirs is examined. The inclusion of a separate model for the free fluid flow in the wellbore is essential to allow for hydraulic communication and mixing of the fluid issuing from different reservoir layers. A two-dimensional model coupling Darcy flow in the reservoir with Navier-Stokes flow in the wellbore is developed and solved by the finite element technique. The coupled wellbore-reservoir flow model is used to analyze a layered reservoir with an abrupt change in permeability and a thick formation showing a gradual change in permeability with depth. Contrary to conventional reservoir models, this new model is able to capture...
A finite volume central differencing scheme for simulation of the shut down procedure of a hydraulic system
, Article International Journal of Fluid Power ; Volume 3, Issue 2 , 2002 , Pages 17-27 ; 14399776 (ISSN) ; Farahani, R. H ; Sharif University of Technology
2002
Abstract
A new central differencing finite volume scheme is investigated for solution of unsteady hydraulic problems as water hammer in pipe systems. Special time stepping procedure similar to Runge-Kutta algorithm is used to stabilize this second order scheme. It is monotonized by adding dissipative terms including second and fourth derivatives of the conserved variables, with coefficients proportional to derivatives of pressure or volumetric flow, which keeps the second order of accuracy in smooth flow regions. The one-dimensional unsteady incompressible equations are solved for a water hammer situation, and results are compared to existing analytical solutions. Results are also compared with...
A fully coupled element-free Galerkin model for hydro-mechanical analysis of advancement of fluid-driven fractures in porous media
, Article International Journal for Numerical and Analytical Methods in Geomechanics ; Volume 40, Issue 16 , 2016 , Pages 2178-2206 ; 03639061 (ISSN) ; Pak, A ; Sharif University of Technology
John Wiley and Sons Ltd
Abstract
Hydraulic fracturing (HF) of underground formations has widely been used in different fields of engineering. Despite the technological advances in techniques of in situ HF, the industry uses semi-analytical tools to design HF treatment. This is due to the complex interaction among various mechanisms involved in this process, so that for thorough simulations of HF operations a fully coupled numerical model is required. In this study, using element-free Galerkin (EFG) mesh-less method, a new formulation for numerical modeling of hydraulic fracture propagation in porous media is developed. This numerical approach, which is based on the simultaneous solution of equilibrium and continuity...
A generalized semi-analytical solution for the dispersive henry problem: effect of stratification and anisotropy on seawater intrusion
, Article Water (Switzerland) ; Volume 10, Issue 2 , 2018 ; 20734441 (ISSN) ; Koohbor, B ; Belfort, B ; Ataie Ashtiani, B ; Simmons, C. T ; Younes, A ; Ackerer, P ; Sharif University of Technology
MDPI AG
2018
Abstract
The Henry problem (HP) continues to play a useful role in theoretical and practical studies related to seawater intrusion (SWI) into coastal aquifers. The popularity of this problem is attributed to its simplicity and precision to the existence of semi-analytical (SA) solutions. The first SA solution has been developed for a high uniform diffusion coefficient. Several further studies have contributed more realistic solutions with lower diffusion coefficients or velocity-dependent dispersion. All the existing SA solutions are limited to homogenous and isotropic domains. This work attempts to improve the realism of the SA solution of the dispersive HP by extending it to heterogeneous and...
A GIS-google earth based approach to estimating the flood damage function in large river basins
, 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 3811-3821 ; 9780784411735 (ISBN) ; Dashti, M ; Alamdari, N ; Salavitabar, A ; Sharif University of Technology
2011
Abstract
Flood as a natural disaster causes heavy human and economic losses and social unrests in most areas of the world. As flood control cost and flood damage compensation is a heavy burden over countries' budget, traditional flood design methods are being replaced by more reliable risk-based methods employing comprehensive risk analysis. In this respect, flood damage estimation is an important step in flood control systems design and analysis. In large river basins with complex reservoir systems and various land uses, flood damage estimation is complex, data-intensive, time demanding, and uncertain task requiring an intensive hydrologic and hydraulic analysis. In this study a simple approach is...
A hybrid pole climbing and manipulating robot with minimum DOFs for construction and service applications
, Article Industrial Robot ; Volume 32, Issue 2 , 2005 , Pages 171-178 ; 0143991X (ISSN) ; Zakerzadeh, M. R ; Vossoughi, G. R ; Bagheri, S ; Sharif University of Technology
2005
Abstract
Purpose - Aims to describe design, prototyping and characteristics of a pole climbing/manipulating robot with ability of passing bends and branches of the pole. Design/methodology/approach - Introducing a hybrid (parallel/serial) four degree of freedom (DOF) mechanism as the main part of the robot and also introduces a unique gripper design for pole climbing robots. Findings - Finds that a robot, with the ability of climbing and manipulating on poles with bends and branches, needs at least 4 DOFs. Also an electrical cylinder is a good option for climbing robots and has some advantages over pneumatic or hydraulic cylinders. Research limitations/implications - The robot is semi-industrial...
A low cost Hydrokinetic Wells turbine system for oceanic surface waves energy harvesting
, Article Renewable Energy ; Volume 156 , 2020 , Pages 610-623 ; Abbaspour, M ; Taeibi Rahni, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This paper provides a feasibility study on a low cost system called Hydrokinetic Wells turbine for surface wave energy conversion without using plenum chambers. The elimination of the plenum chamber and its complicated valve systems can reduce the expenses of wave energy conversion up to 23%.The feasibility process were done for high and low frequency conditions. For the low frequency waves, we offer the 300 rpm angular velocity as an optimum selection for further studies. For the high frequency condition a reliable analytical approach based on validated methods was developed. The analytical results indicate that a wells turbine with 60 cm diameter could produce up to 1600 Watts power in...
A mesh-independent finite element formulation for modeling crack growth in saturated porous media based on an enriched-FEM technique
, Article International Journal of Fracture ; Vol. 188, issue. 1 , 2014 , p. 79-108 ; Vahab, M ; Haghighat, E ; Moallemi, S ; Sharif University of Technology
Abstract
In this paper, the crack growth simulation is presented in saturated porous media using the extended finite element method. The mass balance equation of fluid phase and the momentum balance of bulk and fluid phases are employed to obtain the fully coupled set of equations in the framework of u - p formulation. The fluid flow within the fracture is modeled using the Darcy law, in which the fracture permeability is assumed according to the well-known cubic law. The spatial discritization is performed using the extended finite element method, the time domain discritization is performed based on the generalized Newmark scheme, and the non-linear system of equations is solved using the...
A metal organic framework-polyaniline nanocomposite as a fiber coating for solid phase microextraction
, Article Journal of Chromatography A ; Volume 1431 , 2016 , Pages 27-35 ; 00219673 (ISSN) ; Javanmardi, H ; Abbasi, A ; Banihashemi, S ; Sharif University of Technology
Elsevier B. V
Abstract
A metal organic framework-polyaniline (MOF/PANI) nanocomposite was electrodeposited on a stainless steel wire and used as a solid phase microextraction (SPME) fiber coating. The electropolymerization process was carried out under a constant deposition potential and applied to the corresponding aqueous electrolyte containing aniline and MOF particles. The employment of MOFs with their large and small cages and 3-D structures in synthesizing a nanocomposite was assumed to be efficient constitutes to induce more non-smooth and porous structures, approved by scanning electron microscopy (SEM) images. Three different MOFs were incorporated to synthesize the desired nanocomposites and the...
Anaerobic digestion of vegetable waste
, Article Chemical Engineering Transactions ; Volume 24 , 2011 , Pages 1291-1296 ; 19749791 (ISSN) ; Shayegan, J ; Sharif University of Technology
Italian Association of Chemical Engineering - AIDIC
2011
Abstract
Fruit and vegetable wastes are produced in large quantities in Iran, and constitute a source of nuisance in municipal landfills. The objective of this study was to optimize the applications of anaerobic digestion for the treatment of municipal organic wastes. We studied the effect of organic loading rates on anaerobic digestion of vegetable wastes. The complete-mix, pilot-scale digester with working volume of 70 1 was used. The experiments were conducted at 34°C with a fixed hydraulic retention time of 25 days. The digester was operated at different organic feeding rates of 1.4, 2 and 2.75 kg VS/(m3.d). The biogas produced had methane composition of 49.7- 64% and biogas production rates of...
Analysis of accumulators configuration in LB-LOCA for Bushehr NPP
, Article Annals of Nuclear Energy ; Volume 92 , 2016 , Pages 96-106 ; 03064549 (ISSN) ; Jafari, J ; Aghaie, M ; Vosoughi, N ; Nemati, M ; Sharif University of Technology
Elsevier Ltd
Abstract
This research focuses on a sensitivity analysis of accumulators configuration in a Large Break Loss of Coolant Accident (LB-LOCA) in Bushehr Nuclear Power Plant (BNPP). In this way, primary and secondary side components are modeled using RELAP5/MOD3.3 code. Having modeled the BNPP in a steady state hot full power operation, the thermal hydraulic consequences of a LB-LOCA in the reactor inlet is considered and sensitivity analysis for four major different configurations of accumulators are studied in detail. It is shown that any arrangement of accumulators in the Reactor Pressure Chamber (RPC) or Reactor Collection Chambers (RCC) leads to variation of fuel and clad temperatures during the...
Analysis of evaporating liquid bridge in horizontal fractures
, Article Journal of Petroleum Science and Engineering ; Volume 202 , 2021 ; 09204105 (ISSN) ; Ghazanfari, M.H ; Masihi, M ; Sharif University of Technology
Elsevier B.V
2021
Abstract
The formation of liquid bridge is pertinent to many fields including seepage into underground fractured rocks as an environmental issue and capillary continuity between matrix blocks which controls oil recovery in fractured reservoirs. Evaporation from the surface of liquid bridge into the surrounding gas could affect the stability of liquid bridge and fracture capillary pressure, which is not well discussed in the available literatures. In this research, by the aid of analogy between the diffusive flux and electrostatic potential, a new model for predicting evaporation rate from a liquid bridge inside a horizontal fracture is presented. The proposed model is then coupled with Young-Laplace...
Analysis of the effect of kevlar fibers on abrasion resistance, flexural strength and hydraulic conductivity coefficient of silica fume concretes
, Article Iranian Journal of Science and Technology - Transactions of Civil Engineering ; Volume 44, Issue 2 , 2020 , Pages 669-674 ; Piroti, S ; Ghameian, M ; Sharif University of Technology
Springer
2020
Abstract
Reinforcing fiber and silica fume of concrete can be considered as one of the most widely used additives. In this study, with a review of the history and advantages of using silica fume and polypropylene fibers in concrete, 380 concrete laboratory samples were constructed, of which 25 mixing designs with water–cement ratio of 0.35 and fiber content of 0.2, 0.3, 0.4 and 0.5 of concrete volume and 7% silica fume were prepared according to the ACI standard in their manufacturing. In the present research, samples of Kevlar fiber containing silica fume were tested under flexural strength, abrasion resistance and hydraulic conductivity coefficient. According to achieved results, the optimum amount...
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...
Analyzing and predicting permeability coefficient of roller-compacted concrete (RCC)
, Article Journal of Testing and Evaluation ; Volume 49, Issue 3 , 2019 ; 00903973 (ISSN) ; Toufigh, V ; Ghaemian, M ; Sharif University of Technology
ASTM International
2019
Abstract
The permeability of roller-compacted concrete (RCC) substantially affects its functionality and safety. This study investigates the effect of mix design parameters on the performance of RCC. For this purpose, approximately 500 laboratory specimens were prepared and tested. A formula and an artificial neural network (ANN) were proposed to predict the permeability coefficient of RCC by considering the main parameters, which were then verified independently using new specimens. Furthermore, the experimental data were analyzed by the Taguchi method and analysis of variance (ANOVA) to evaluate the level of parameter contribution. Based on the results, the permeability coefficient was highly...
An ant-based rate allocation algorithm for media streaming in peer to peer networks: Extension to multiple sessions and dynamic networks
, Article Journal of Network and Computer Applications ; Volume 34, Issue 1 , 2011 , Pages 327-340 ; 10848045 (ISSN) ; Salavati, A. H ; Pakravan, M. R ; Sharif University of Technology
Abstract
In this paper, we introduce a novel algorithm for rate allocation in media streaming P2P networks where multimedia contents are distributed among network members and streamed toward any requesting peer. The proposed algorithm is based on ant-colony optimization. It is capable of handling network dynamism, which is an inherent property of unstructured P2P networks. Another advantage of our algorithm is its ability to get over uncertainties in network state information, particularly the rate of supplying peers that could happen due to lack of accurate measurements. In addition, the suggested method does not rely on any information about the topology of the network. We have investigated both...