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Numerical Study and Optimization of Effective Parameters in Freeze Desalination
, M.Sc. Thesis Sharif University of Technology ; Afshin, Hossein (Supervisor)
Abstract
Freeze desalination as a water refining method has attracted a lot of attention due to its potential in lowering process energy consumption compared to other methods. This method is based on the fact that the dissolved salt is drained from the saline water during its freezing. The current study conducts a parametric study on freezing saline water in a cylindrical container to investigate the impact of geometric and functional factors affecting the desalination quality. This has been done by examining the aforesaid factors in the form of dimensionless parameters such as thermal Grashof number, solutal Grashof number, and Jacob number. In addition, in order to improve the desalination, a novel...
Semi-Analytical Modeling And Simulation Of Heavy Oil Recovery Through VAPEX Process
, M.Sc. Thesis Sharif University of Technology ; Masihi, Mohsen (Supervisor) ; Kharrat, Riyaz (Supervisor)
Abstract
VAPEX is a relatively new EOR process for the recovery of heavy oil. In this process solvent is used to form a vapor chamber within a reservoir. Vapor dissolves in the oil and diluted oil drains by gravity to a horizontal production well. The essential features of this recovery mechanism have been discussed in this study. Furthermore, a semi-analytical and a simulation study of VAPEX process have been performed on a specified Iranian heavy oil reservoir (such as Kuh-e-Mond). The aim of this study is to investigate an exponential functionality (correlation) witch incorporates all physical parameters that affect the production rate of VAPEX process in dimensionless form. The adjustable...
Mechanistic Studies of Improved Oil Recovery under Forced Gravity Drainage GAGD Process
, Ph.D. Dissertation Sharif University of Technology ; Kharrat, Riyaz (Supervisor) ; Ghotbi, Cyrus (Supervisor) ; Pooladi Darvish, Mehran (Co-Advisor)
Abstract
Gas-oil displacement, when stabilized by gravity forces leads to high displacement efficiency, as manifested in high recovery factor associated with gas-cap drive and gravity drainage. The main objective of this research is improved understanding of drainage behavior and changes in flow properties when the importance of viscous, gravity and capillary forces varies. The influence of interplaying between controlling forces on relative permeabilities is also studied. Another objective of this work is to study effect of wettability on recovery under forced gravity drainage. To study drainage behavior under various dominant driving/resistive forces, a number of forced gravity drainage experiments...
Wettability effects in gas gravity-Assisted flow as related to displacement instability
, Article Special Topics and Reviews in Porous Media ; Volume 1, Issue 1 , 2010 , Pages 39-47 ; 21514798 (ISSN) ; Kharrat, R ; Alipour Tabrizy, V ; Khosravi, M ; Ghotbi, C ; Sharif University of Technology
Abstract
The drainage of oil under gravity forces is an efficient method because it can farther reduce the remaining oil saturation to below that obtained after water flooding. This paper describes a series of visual experiments under forced gas invasion with special attention to the effects of wettability. From oil production history and image analysis, we examine a threshold criterion for displacement stability that is consistent with the results of gradient percolation theory. The effect of the destabilized front velocity on oil recovery and residual saturation is investigated for both wettability conditions. Different recovery rates occur with different fluid morphologies, which depend on the...
Transformation of sliding motion to rolling during spheres collision
, Article Granular Matter ; Volume 19, Issue 4 , 2017 ; 14345021 (ISSN) ; Kaviani Rad, H ; Jafari Shad, H ; Sharif University of Technology
Abstract
In this research, we have investigated the three-dimensional elastic collision of two balls, based on friction in the tangential plane. Our aim is to offer analytical closed form relations for post collision parameters such as linear and angular velocities, collision time and tangential and normal impulse in three dimensions. To simplify the problem, stick regime is not considered. In other words, balls have a low tangential coefficient of restitution. Sliding, sliding then rolling, and rolling at the beginning of contact are three cases that can occur during impact which have been considered in our research. The normal interaction force is described by the Hertz contact force and...
Test-retest reliability of Kinect's measurements for the evaluation of upper body recovery of stroke patients
, Article BioMedical Engineering Online ; Volume 14, Issue 1 , 2015 ; 1475925X (ISSN) ; Behzadipour, S ; Saadat, M ; Sharif University of Technology
BioMed Central Ltd
2015
Abstract
Background: Performance indices provide quantitative measures for the quality of motion, and therefore, assist in analyzing and monitoring patients' progress. Measurement of performance indices requires costly devices, such as motion capture systems. Recent developments of sensors for game controllers, such as Microsoft Kinect, have motivated many researchers to develop affordable systems for performance measurement applicable to home and clinical care. In this work, the capability of Kinect in finding motion performance indices was assessed by analyzing intra-session and inter-session test-retest reliability. Method: Eighteen stroke patients and twelve healthy subjects participated in this...
Steady state creep behavior of short fiber composites by mapping, logarithmic functions (MF) and dimensionless parameter (DP) techniques
, Article Archives of Civil and Mechanical Engineering ; Volume 12, Issue 4 , December , 2012 , Pages 455-463 ; 16449665 (ISSN) ; Mondali, M ; Abedian, A ; Sharif University of Technology
2012
Abstract
A new mathematical insight based on logarithmic, polynomial mapping functions (MF), and dimensionless parameter (DP) models is presented for determination of some unknowns in the steady state creep stage of short fiber composites subjected to axial loading. These unknowns are displacement rate in outer surface of the unit cell, shear and equivalent stresses at interface and outer surface of the unit cell, and average axial stress in fiber. Dimensionless parameter technique is presented for determination of displacement rate and equivalent stress in outer surface of the unit cell. However, the polynomial mapping function is presented for determination of average axial stress in fiber. Most...
Splitting dynamics of ferrofluid droplets inside a microfluidic T-junction using a pulse-width modulated magnetic field in micro-magnetofluidics
, Article Soft Matter ; Volume 17, Issue 5 , 2021 , Pages 1317-1329 ; 1744683X (ISSN) ; Dizani, M ; Honarmand, M ; Shafii, M. B ; Sharif University of Technology
Royal Society of Chemistry
2021
Abstract
Micro-magnetofluidics offers a promising tool for better control over the ferrofluid droplet manipulation which has been vastly utilized in biomedical applications in recent years. In this study, the ferrofluid droplet splitting under an asymmetric Pulse-Width-Modulated (PWM) magnetic field in a T-junction is numerically investigated using a finite volume method and VOF two-phase model. By utilizing the PWM magnetic field, two novel regimes of ferrofluid droplet splitting named as Flowing through the Same Branch (FSB) and Double Splitting (DS) have been observed for the first time. In the FSB regime, the daughter droplets move out of the same microchannel outlet, and in the DS regime, the...
Sea-level rise impact on fresh groundwater lenses in two-layer small islands
, Article Hydrological Processes ; Vol. 28, issue. 24 , 2014 , p. 5938-5953 ; Mahmoodzadeh, D ; Ataie-Ashtiani, B ; Werner, A. D ; Simmons, C. T ; Sharif University of Technology
Abstract
The fresh groundwater lenses (FGLs) of small islands can be highly vulnerable to climate change impacts, including sea-level rise (SLR). Many real cases of atoll or sandy islands involve two-layer hydrogeological conceptualizations. In this paper, the influential factors that affect FGLs in two-layer small islands subject to SLR are investigated. An analytical solution describing FGLs in circular islands, composed of two geological layers, is developed for the simplified case of steady-state and sharp-interface conditions. An application of the developed model is demonstrated to estimate the FGL thickness of some real-world islands by comparison with existing FGL thickness data. Furthermore,...
Scaling equations for oil/gas recovery from fractured porous media by counter-current spontaneous imbibition: From development to application
, Article Energy and Fuels ; Vol. 27, issue. 8 , July , 2013 , p. 4662-4676 ; ISSN: 08870624 ; Masihi, M ; Sharif University of Technology
Abstract
Spontaneous imbibition, the capillary-driven process of displacing the nonwetting phase by the wetting phase in porous media, is of great importance in oil/gas recovery from matrix blocks of fractured reservoirs. The question of how properly scaling up the recovery by counter-current spontaneous imbibition has been the subject of extensive research over decades, and numerous scaling equations have been proposed. As a convention, the scaling equations are usually defined analytically by relating the early time squared recovery to squared pore volume. We show this convention does not apply to common scaling practices and, if used, causes nontrivial scatter in the scaling plots. We explain that...
Scaling equations for oil/gas recovery from fractured porous media by counter-current spontaneous imbibition: From development to application
, Article Energy and Fuels ; Volume 27, Issue 8 , 2013 , Pages 4662-4676 ; 08870624 (ISSN) ; Masihi, M ; Sharif University of Technology
2013
Abstract
Spontaneous imbibition, the capillary-driven process of displacing the nonwetting phase by the wetting phase in porous media, is of great importance in oil/gas recovery from matrix blocks of fractured reservoirs. The question of how properly scaling up the recovery by counter-current spontaneous imbibition has been the subject of extensive research over decades, and numerous scaling equations have been proposed. As a convention, the scaling equations are usually defined analytically by relating the early time squared recovery to squared pore volume. We show this convention does not apply to common scaling practices and, if used, causes nontrivial scatter in the scaling plots. We explain that...
Rule of thumb for gas permeation systems' calculations
, Article Petroleum and Coal ; Volume 57, Issue 4 , 2015 , Pages 360-365 ; 13377027 (ISSN) ; Mivechian, A ; Sharif University of Technology
Slovnaft VURUP a.s
2015
Abstract
In gas purification using polymeric membrane systems, different parameters affect on product specification. In these systems, pressure ratio, stage-cut, membrane selectivity and feed purity are important parameters which changing in these parameters results in a different product specification. Existence of a mathematical correlation between these parameters can be helpful and it gives a view that shows how can approach to products with desired specification. In present study, a correlation between effective parameters has been developed. This dimensionless mathematical model shows how product purity and recovery are influenced by membrane selectivity (DR; from 2 to 125) and feed purity in...
Relationship between wetting properties and macroscale hydrodynamics during forced gravity drainage and secondary waterflood
, Article Petroleum Science and Technology ; Volume 28, Issue 8 , 2010 , Pages 804-815 ; 10916466 (ISSN) ; Kharrat, R ; Ghotbi, C ; Alipour Tabrizy, V ; Sharif University of Technology
Abstract
In order to relate the wetting properties at the pore scale to the macroscale prevailing forces, a series of experiments was performed in vertical porous media under forced gas invasion at various wettability conditions with partially spreading oil. To describe the dynamics of oil recovery in a three-phase flow condition, the downward gas flood experiments were continued by water injection from the bottom. Experimental results obtained in situations where the magnitudes of viscous, capillary, and gravity forces are comparable. We study the transition from flow configurations where the interface is stable with respect to viscous instability to flow configurations where viscous fingering...
Proposing a general formula to calculate the critical velocities in tunnels with different cross-sectional shapes
, Article Tunnelling and Underground Space Technology ; Volume 110 , 2021 ; 08867798 (ISSN) ; Farhanieh, B ; Afshin, H ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Among the parameters affecting the critical velocity in tunnel fires, the tunnel cross-sectional shape could significantly affect the tunnel fire characteristics, mainly due to the wall-bounded physics of the tunnel fire. Previously, the effects of the cross-sectional geometry of the tunnel were calculated using the non-dimensional analysis and hydraulic height of the tunnel. The dimensionless analysis using hydraulic height calculates only the effects of the tunnel sizes and does not capture the effects of the shape of the tunnel cross-section. Developing a 3D computational fluid dynamics tool using the body-fitted grids, the critical velocities are calculated for the 7 different...
Pressure and temperature functionality of paraffin-carbon dioxide interfacial tension using genetic programming and dimension analysis (GPDA) method
, Article Journal of Natural Gas Science and Engineering ; Volume 20 , September , 2014 , Pages 407-413 ; ISSN: 18755100 ; Jahromi, I. R ; Zolghadr, A ; Ayatollahi, S ; Sharif University of Technology
Abstract
A precise semi-empirical correlation for the calculation of interfacial tension (IFT) between the carbon dioxide and paraffin group to be used in an enhanced oil recovery process and the chemical industry is introduced. Genetic programming and dimension analysis (GPDA) are combined to create a correlation for the calculation of the equilibrium interfacial tension of the carbon dioxide and paraffin group, based on the explicit functionality of the pressure and temperature. The parameters of the correlation consist of critical temperature, critical pressure, density of paraffin at normal temperature, and diffusion coefficients. The pool of experimental data for developing the correlation...
Numerical simulation of collision between two droplets in the T-shaped microchannel with lattice Boltzmann method
, Article AIP Advances ; Volume 6, Issue 11 , 2016 ; 21583226 (ISSN) ; Ebrahimi, S ; Moosavi, A ; Shafii, M. B ; Kowsary, F ; Sharif University of Technology
American Institute of Physics Inc
Abstract
In this study, the Lattice Boltzmann Method (LBM) is used to investigate the deformation of two droplets within microfluidic T-junctions (MFTD). In order to increase the accuracy the two immiscible fluids are modeled using the He-Chen-Zhang model. First, this model is applied to ensure that the surface tension effect existing between the droplets and the continuous fluid is properly implemented in the model. Then the collision and merging of the two droplets within the intersection of a T-shaped microchannel is investigated. For generating droplet formation the effects of relevant dimensionless parameters such as the Reynolds, the Weber numbers as well as a collision parameter affecting the...
Nonlinear vibration analysis of nano to micron scale beams under electric force using nonlocal theory
, Article Proceedings of the ASME Design Engineering Technical Conference, 28 August 2011 through 31 August 2011 ; Volume 7 , August , 2011 , Pages 145-151 ; 9780791854846 (ISBN) ; Vaghasloo, Y. A ; Ahmadian, M. T ; Moheimani, R ; Sharif University of Technology
2011
Abstract
Electrostatically actuated beams are fundamental blocks of many different nano and micro electromechanical devices. Accurate design of these devices strongly relies on recognition of static and dynamic behavior and response of mechanical components. Taking into account the effect of internal forces between material particles nonlocal theories become highly important. In this paper nonlinear vibration of a microano doubly clamped and cantilever beam under electric force is investigated using nonlocal continuum mechanics theory. Implementing differential form of nonlocal constitutive equation the nonlinear partial differential equation of motion is reformulated. The equation of motion is...
Nonlinear analysis of chatter in turning process using dimensionless groups
, Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 37, Issue 4 , July , 2015 , Pages 1151-1162 ; 16785878 (ISSN) ; Jalili, M. M ; Movahhedy, M. R ; Sharif University of Technology
Springer Verlag
2015
Abstract
A new 3-D nonlinear model of chatter vibration in turning process is presented in this paper. The workpiece is modeled as a rotating clamped-free beam which is excited by cutting forces. π-Buckingham theory is used to extract dimensionless parameters for this problem. Using these parameters, non-dimensional equations of motion are developed. An approximate analytical solution of the nonlinear problem is obtained. A study of the influence of different parameters on the stability results is developed. Using these results, turning velocity intervals for stable and unstable cuts are determined
Modeling and CFD simulation of a mixed-convection flow of regular fluids and nanofluids in vertical porous and regular channels
, Article Heat Transfer - Asian Research ; Vol. 43, issue. 3 , May , 2014 , pp. 243-269 ; ISSN: 1523-1496 ; Dehkordi, A. M ; Sharif University of Technology
Abstract
In this article, the problem of combined forced and free convection in vertical porous and regular channels for both regular fluids and nanofluids has been solved using the CFD technique in the entrance regions of momentum and heat transfer taking into account the influences of viscous heating and inertial force. In this regard, various types of viscous dissipation models reported in the literature such as the Darcy model, the power of the drag force model, and the clear fluid-compatible model were applied. In the case of nanofluid flow, both the Brownian and thermophoresis molecular transfer mechanisms were considered. The dimensionless distributions of velocity, temperature, and the volume...
Mixed pressure and AC electroosmotically driven flow with asymmetric wall zeta potential and hydrophobic surfaces
, Article ASME 2013 Heat Transfer Summer Conf. Collocated with the ASME 2013 7th Int. Conf. on Energy Sustainability and the ASME 2013 11th Int. Conf. on Fuel Cell Science, Engineering and Technology, HT 2013 ; Volume 1 , 2013 ; 9780791855478 (ISBN) ; Sharif University of Technology
2013
Abstract
The present study examines Alternating Current (AC) electroosmotic flows in a parallel plate microchannel subject to constant wall temperature. Numerical method consists of a central finite difference scheme for spatial terms and a forward difference scheme for the temporal term. Asymmetric boundary conditions are assumed for Poison-Boltzmann equation for determining the electric double layer (EDL) potential distribution. The potential distribution is then used to evaluate the velocity distribution. The velocity distribution is obtained by applying slip boundary conditions on the walls which accounts for probable hydrophobicity of surfaces. After determining the velocity distribution...