Loading...
Search for:
mesh-generation
0.008 seconds
Total 69 records
Vorticity-Bases Adaptive Mesh Refinement for Upscaling of Highly Heterogeneous Porous Media
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
The results of numerical simulation of underground flows are greatly affected not only by the discretization method of flow equations, but also by the way that the geological domain is upscaled. Including the detailed knowledge of heterogeneous permeability distribution is mostly neither feasible nor computationally efficient. So it is important to develop efficient grid generation and upscaling methods to simplify the fine-scale flow model while still including the impact of the heterogeneities as far as possible. Thus regions where parameters of interest have larger values or higher changes require finer grid blocks and regions with lower values or minor changes should have coarser grid...
Investigation of the Fire-Induced Smoke Flow in the Complex Geometries Using The 3d Numerical Method and the Body-Fitted Curvilinear Coordinates
, Ph.D. Dissertation Sharif University of Technology ; Farhanieh, Bijan (Supervisor) ; Afshin, Hossein (Co-Supervisor)
Abstract
With the process of achieving a higher state of social development and technological advances, the need for higher and more strict safety standards has been increased. In this regard, it is of great importance to have an accurate understanding of the fire phenomena and its consequences. Among the adverse effects of fire, a significant percentage of the fire fatalities is related to the fire-induced buoyant gases (smoke) flow which can lead to suffocation. Therefore, it is necessary to know the physics of the fire phenomena well. In fire investigation methods, the numerical study is an appropriate choice, because of the lower executive cost (relative to the experimental study) and the wider...
Vorticity-based coarse grid generation for upscaling two-phase displacements in porous media
, Article Journal of Petroleum Science and Engineering ; Volume 59, Issue 3-4 , 2007 , Pages 271-288 ; 09204105 (ISSN) ; Firoozabadi, B ; Mahani, H ; Khoozan, D ; Sharif University of Technology
2007
Abstract
Coarse grid generation from finely gridded geological model is a main step in reservoir simulation. Coarse grid generation algorithms aim at optimizing size, number and location of the grid blocks by identifying the important geological and flow features which control flow in porous media. By optimizing coarse grid structure we can improve accuracy of the coarse scale simulation results to reproduce fine grid behavior. A number of techniques have been proposed in the literature. We present a novel coarse grid generation procedure based on vorticity preservation between fine and coarse grids. In the procedure, the coarse grid mesh tries to capture variations in both permeability and fluid...
Vorticity as a measure of heterogeneity for improving coarse grid generation
, Article Petroleum Geoscience ; Volume 15, Issue 1 , 2009 , Pages 91-102 ; 13540793 (ISSN) ; Muggeridge, A. H ; Ashjari, M. A ; Sharif University of Technology
2009
Abstract
This paper presents a novel coarse grid generation technique based on using vorticity as a measure of the impact of heterogeneity on flow. Vorticity is a maximum when the total flow is high and perpendicular to a large permeability gradient. Maps of vorticity were generated from single-phase flow simulations and used to generate coarse simulation grids from finely gridded geological models. The resulting grid was more refined in areas of high vorticity and coarser in areas of low vorticity. The method is first demonstrated on a simple five-layered model before being applied to three, 2D models of geologically realistic heterogeneity. The homogenized model generated from vorticity maps shows...
Unstructured-coarse-grid generation usina backaround-grid approach
, Article SPE Journal ; Volume 15, Issue 2 , 2010 , Pages 326-340 ; 1086055X (ISSN) ; Mahani, H ; Sharif University of Technology
2010
Abstract
Reservoir flow simulation involves subdivision of the physical domain into a number of gridblocks. This is best accomplished with optimized gridpoint density and a minimized number of gridblocks, especially for coarse-grid generation from a fine-grid geological model. In any coarse-grid generation, proper distribution of gridpoints, which form the basis of numerical gridblocks, is a challenging task. We show that this can be achieved effectively by a novel grid-generation approach based on a background grid that stores gridpoint spacing parameters. Spacing parameter (L) can be described by Poisson's equation (▽2L = G), where the local density of gridpoints is controlled by a variable source...
Unstructured coarse grid generation for reservoir flow simulation using background grid approach
, Article 16th Middle East Oil and Gas Show and Conference 2009, MEOS 2009, Manama, 15 March 2009 through 18 March 2009 ; Volume 2 , 2009 , Pages 685-697 ; 9781615670123 (ISBN) ; Mahani, H ; Sharif University of Technology
2009
Abstract
Reservoir flow simulation involves subdivision of the physical domain into a number of gridblocks. This is best accomplished with optimized grid point density and minimized number of gridblocks especially for coarse grid generation from a fine grid geological model. In any coarse grid generation, proper distribution of grid points, which form basis of numerical gridblocks, is a challenging task. We show that this can be effectively achieved by generating a background grid that stores grid point spacing parameter. Spacing (X) can be described by Poisson's equation (∇2 L = G) where the local density of grid points is controlled by a variable source term (G). This source term can be based on...
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...
Ultrafast two-step synthesis of s-doped Fe/Ni (Oxy)Hydroxide/Ni nanocone arrays on carbon cloth and stainless-steel substrates for water-splitting applications
, Article ACS Applied Energy Materials ; Volume 4, Issue 10 , 2021 , Pages 10627-10638 ; 25740962 (ISSN) ; Shahrokhian, S ; Sharif University of Technology
American Chemical Society
2021
Abstract
Nonprecious and effective electrocatalyst development is an essential requirement for boosting water-splitting efficiency to obtain clean and sustainable fuels for future renewable energy demands. Herein, we reported an ultrafast and feasible strategy for constructing an S-doped bimetallic iron/nickel oxy(hydroxide) (S-(Fe/Ni)OOH) as a superior electrocatalyst for oxygen evolution reaction (OER). It is prepared by consequent electroplating of nickel nanocone arrays (NiNCAs) on carbon cloth (CC) and stainless-steel mesh (SSM) and then formation of S-(Fe/Ni)OOH layers on them by ultrafast one-step oxidation solution-phase method in the solution of Fe3+ and sodium thiosulfate at room...
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...
The triangular pyramid: Routing and topological properties
, Article Information Sciences ; Vol. 180, issue. 11 , 2010 , p. 2328-2339 ; ISSN: 00200255 ; Sarbazi-Azad, H ; Sharif University of Technology
Abstract
In this paper, a new topology for multicomputer interconnection networks, based on triangular mesh, is proposed. The new network, referred to as the triangular pyramid (or tripy for short), has L levels of triangular mesh. We study some basic important properties of the proposed network as well as introduce a routing algorithm for the tripy network based on the routing of triangular meshes. We prove that this form of pyramidal network is Hamiltonian, Hamiltonian-connected, and pancyclic. We also prove that the proposed network is 6-colorable and conduct a brief comparison of the tripy and its traditional pyramid counterpart. Our results show that the proposed network has higher scalability,...
The triangular pyramid: Routing and topological properties
, Article Information Sciences ; Volume 180, Issue 11 , June , 2010 , Pages 2328-2339 ; 00200255 (ISSN) ; Sarbazi Azad, H ; Sharif University of Technology
2010
Abstract
In this paper, a new topology for multicomputer interconnection networks, based on triangular mesh, is proposed. The new network, referred to as the triangular pyramid (or tripy for short), has L levels of triangular mesh. We study some basic important properties of the proposed network as well as introduce a routing algorithm for the tripy network based on the routing of triangular meshes. We prove that this form of pyramidal network is Hamiltonian, Hamiltonian-connected, and pancyclic. We also prove that the proposed network is 6-colorable and conduct a brief comparison of the tripy and its traditional pyramid counterpart. Our results show that the proposed network has higher scalability,...
The effects of excitation control systems on parallel operation of DG with the main grid
, Article International Journal of Power and Energy Systems ; Volume 28, Issue 4 , 2008 , Pages 438-447 ; 10783466 (ISSN) ; Parniani, M ; Rasouli, M ; Sharif University of Technology
2008
Abstract
This paper presents actual cases of steady reactive power oscillation of distributed generations (DGs) during parallel operation with the main grid. The cause of the problem was found to be the adverse effects of excitation system voltage regulation. It is shown, through preliminary investigation and detailed simulation studies, that how the excitation control system can be modified to overcome this problem. On-site test results verify the analysis results and effectiveness of the remedial actions. Finally, general practical recommendations are offered for excitation control of synchronous generator-based DG, such that it performs properly, both in grid connected and in islanding conditions
Study of subsonic-supersonic gas flow through micro/nanoscale nozzles using unstructured DSMC solver
, Article Microfluidics and Nanofluidics ; Volume 10, Issue 2 , February , 2011 , Pages 321-335 ; 16134982 (ISSN) ; Roohi, E ; Sharif University of Technology
2011
Abstract
We use an extended direct simulation Monte Carlo (DSMC) method, applicable to unstructured meshes, to numerically simulate a wide range of rarefaction regimes from subsonic to supersonic flows through micro/nanoscale converging-diverging nozzles. Our unstructured DSMC method considers a uniform distribution of particles, employs proper subcell geometry, and follows an appropriate particle tracking algorithm. Using the unstructured DSMC, we study the effects of back pressure, gas/surface interactions (diffuse/specular reflections), and Knudsen number on the flow field in micro/nanoscale nozzles. If we apply the back pressure at the nozzle outlet, a boundary layer separation occurs before the...
Stress analysis of three-unit all-ceramic dental bridges using FEM
, Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) ; Farahmand, F ; Shamsaei, N ; Eslami, G. R ; Sharif University of Technology
2006
Abstract
Mechanical fracture is a common cause of failure for 3-unit dental bridges, particularly, the all-ceramic structures. The purpose of the present study was to evaluate the effect of convergence angles of the abutments on the distribution of the mechanical stresses, within the prosthesis and at the restoration-abutments interface of a 3-unit all-ceramic bridge. The 3-D geometrical data of the second premolar and first and second molar teeth were obtained using ATOS scanner system and utilized for reconstruction of a surface model of the 3-unit bridge in I-Deas as solid modeler software. This was then transferred to MSC/Nastran software for mesh generation and finite element analysis. Two FE...
Shaking table tests on dome-roof adobe houses
, Article Earthquake Engineering and Structural Dynamics ; Volume 46, Issue 3 , 2017 , Pages 467-490 ; 00988847 (ISSN) ; Ghannad, M ; Yekrangnia, M ; Masaeli, H ; Sharif University of Technology
John Wiley and Sons Ltd
2017
Abstract
This paper presents the results of an experimental work in order to evaluate the performance of a novel proposed retrofitting technique on a typical dome-roof adobe building by shaking table tests. For this purpose, two specimens, scaled 2:3, were subjected to a total of nine shaking table tests. The unretrofitted specimen, constructed by common practice, is designed to evaluate seismic performance and vulnerability of dome-roof adobe houses. The retrofitted specimen, exactly duplicating the first specimen, is retrofitted based on the results obtained from unretrofitted specimen tests, and the improvement in seismic behavior of the structure is investigated. Zarand earthquake (2005) Chatrood...
RuO2 /MWCNT/ stainless steel mesh as a novel positive electrode in vanadium redox flow batteries
,
Article
RSC Advances
;
Volume 5, Issue 84
,
Aug
,
2015
,
Pages 68378-68384
;
20462069 (ISSN)
; Faraji, M
;
Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
The present work describes the preparation and electrochemical characterization of RuO2 /MWCNT/Stainless Steel Mesh (SSM) electrode as compared with a MWCNT/SSM electrode in the positive half-cell of a Vanadium Redox Flow Battery (VRFB). The electrochemical characterization of prepared electrode was carried out using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge procedures. The electrochemical activity of MWCNT/SSM modified with RuO2 as positive electrode in a VRFB was notably improved. The RuO2 -included electrodes demonstrated high peak current ratio, small peak potential difference and high electron...
Reservoir flow simulation using combined vorticity-based gridding and multi-scale upscaling
, Article Society of Petroleum Engineers - SPE Asia Pacific Oil and Gas Conference and Exhibition 2007 ""Resources, Professionalism, Technology: Time to Deliver"", Jakarta, 30 October 2007 through 1 November 2007 ; Volume 2 , 2007 , Pages 927-946 ; 9781604238594 (ISBN) ; Ashjari, M. A ; Firoozabadi, B ; Sharif University of Technology
Society of Petroleum Engineers (SPE)
2007
Abstract
A novel technique for upscaling of detailed geological reservoir descriptions is presented. The technique aims at reducing both numerical dispersion and homogenization error, generated due to incorporating a coarse computational grid and assigning effective permeability to coarse grid blocks respectively. In particular we consider implicit-pressure explicit-saturation (IMPES) scheme where homogenization error impacts the accuracy of the coarse grid solution of the pressure equation. To reduce the homogenization error, we employ the new vorticity-based gridding that generates a non-uniform coarse grid with high resolution at high vorticity zones. In addition, to control numerical dispersion,...
Preparation and characterization of superhydrophobic and highly oleophobic FEVE-SiO2 nanocomposite coatings
, Article Progress in Organic Coatings ; Volume 138 , 2020 ; Dolati, A ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Here, an excellent superhydrophobic and highly oleophobic nanocomposite coating composed of fluoroethylene-vinyl ether (FEVE) resin as a matrix for modified SiO2 nanoparticles was synthesized on a stainless-steel wire mesh substrate via a facile sol-gel method. The surface morphology, microstructure, composition, and roughness of the coatings were investigated by field emission scanning electron microscopy (FESEM) equipped with energy-dispersive spectroscopy (EDS) and atomic force microscopy (AFM). The most efficient coating with superhydrophobicity and high oleophobicity feature indicates the water and oil repellency with contact angles (CAs) of 152° and 141°, respectively, with the high...
Precise localization of neutron noise sources based on transport theory and comparison with diffusion theory
, Article Annals of Nuclear Energy ; Volume 151 , 2021 ; 03064549 (ISSN) ; Vosoughi, N ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In an attempt to explore the significance of transport theory in neutron noise, localization of a noise source by Green's function based on transport theory is investigated. There are considerable differences between Green's functions based on diffusion and transport, such as small dimensions, near edges, high heterogeneity medium and high-frequency source of perturbation. These differences are expected to significantly impact unfolding, reconstruction, and identification of the neutron noise source. Improvement in noise source unfolding methods is essential in terms of safety aspects and reactor performance enhancement. Since gaining the ability to monitor nuclear reactor based on noise...
Power-aware mapping for reconfigurable NoC architectures
, Article 2007 IEEE International Conference on Computer Design, ICCD 2007, Lake Tahoe, CA, 7 October 2007 through 10 October 2007 ; 2007 , Pages 417-422 ; 1424412587 (ISBN); 9781424412587 (ISBN) ; Sarbazi Azad, H ; Sharif University of Technology
2007
Abstract
A core mapping method for reconfigurable network-on-chip (NoC) architectures is presented in this paper. In most of the existing methods, mapping is carried out based on the traffic characteristics of a single application. However, several different applications are implemented and integrated in the modern complex system-on-chips which should be considered by mapping methods. In the proposed method, the reconfiguration (which is achieved by embedding programmable switches between routers of a mesh-based NoC) allows us to dynamically change the network topology in order to adapt it with the running application and optimize the power and performance metrics. The presented network architecture...