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finite-volume-method
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Secondary flows, mixing, and chemical reaction analysis of droplet-based flow inside serpentine microchannels with different cross sections
, Article Langmuir ; Volume 37, Issue 17 , 2021 , Pages 5118-5130 ; 07437463 (ISSN) ; Madadelahi, M ; Dizani, M ; Shamloo, A ; Sharif University of Technology
American Chemical Society
2021
Abstract
Chemical bioreactions are an important aspect of many recent microfluidic devices, and their applications in biomedical science have been growing worldwide. Droplet-based microreactors are among the attractive types of unit operations, which utilize droplets for enhancement in both mixing and chemical reactions. In the present study, a finite-volume-method (FVM) numerical investigation is conducted based on the volume-of-fluid (VOF) applying for the droplet-based flows. This multiphase computational modeling is used for the study of the chemical reaction and mixing phenomenon inside a serpentine microchannel and explores the effects of the aspect ratio (i.e., AR = height/width) of...
Computational analysis of ground effects on the dynamical behavior of unconfined two-phase clouds in view of detonability studies
, Article Scientia Iranica ; Volume 12, Issue 4 , 2005 , Pages 414-425 ; 10263098 (ISSN) ; Doustdar, M. M ; Hosseinalipour, M ; Sharif University of Technology
Sharif University of Technology
2005
Abstract
A numerical analysis has been performed to investigate the ground effects on the main parameters of a two-phase unconfined cloud of fuel and air to study its detonability. Equivalence ratio, turbulence intensity, cloud shape and volume, uniformity, temperature gradient and delay time distribution are the most important factors that affect the detonability of a vapor cloud. The effects of the altitude of the dispersing device from the ground on these significant factors have been demonstrated. A modified KIVA-based program has been employed to carry out the computations. A finite volume method is used to solve the equations describing the gas phase. A discrete particle technique is applied to...
Numerical simulation of a concentrating photovoltaic-thermal solar system combined with thermoelectric modules by coupling Finite Volume and Monte Carlo Ray-Tracing methods
, Article Energy Conversion and Management ; Volume 172 , 2018 , Pages 343-356 ; 01968904 (ISSN) ; Narei, H ; Ghasempour, R ; Shafii, M. B ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
During the last decades, the adoption of more strict safety and environmental regulations, as well as a rise in energy costs, sparked an increasing interest in the design of renewable energies systems, particularly solar systems, to supply both electrical power and heat. Because of their capability to simultaneously supply both electricity and heat, concentrating photovoltaic-thermal and thermoelectric hybrid systems have recently attracted scholarly attention. In this study, a detailed three-dimensional computational model of a novel concentrating photovoltaic-thermal solar system combined with thermoelectric modules in an integrated design with a triangular absorber and corresponding...
Numerical modeling of transient turbulent gas flow in a pipe following a rupture
, Article Scientia Iranica ; Volume 17, Issue 2 B , 2010 , Pages 108-120 ; 10263098 (ISSN) ; Ziaei Rad, M ; Sharif University of Technology
2010
Abstract
The transient flow of a compressible gas generated in a pipeline after an accidental rupture is studied numerically. The numerical simulation is performed by solving the conservation equations of an axisymmetric, transient, viscous, subsonic flow in a circular pipe including the breakpoint. The numerical technique is a combined finite element-finite volume method applied on the unstructured grid. A modified K - ε model with a two-layer equation for the near wall region and compressibility correction is used to predict the turbulent viscosity. The results show that, for example, after a time period of 0.16 seconds, the pressure at a distance of 61.5 m upstream of the breakpoint reduces about...
Developing a Hybrid Continuum-Molecular Method to Analyze Binary Gas Mixing and Separation Processes
, Ph.D. Dissertation Sharif University of Technology ; Darbandi, Masoud (Supervisor)
Abstract
The co-existance of rarefied and near-continuum flow regimes is widelyencountered in analyzing the multiscale flow problems, e.g., micro-and nanoflows. Previous investigations have revealed that the continuum-based simulation methods would suffer from the lack of accuracy to predict the rarefied flow regimes. On the other hand, the molecular simulation methods are not computationally efficient in simulating the near-continuum flow regimes. Therefore, the use of hybrid simulation methods has been recommended as a serious alternative to simulate the multiscale flow problems. These methods apply the molecular methods in solving the rarefied flow regions and the continuum methods in solving the...
Large Eddy Simulation of Excited Jet Flow
, Ph.D. Dissertation Sharif University of Technology ; Farshchi, Mohammad (Supervisor)
Abstract
Excited jet flow has many physical and industrial applications, e.g. in aeroacoustics and the combustion instability. Analysis of this type of flow needs an accurate simulation of flow dynamics. This work presents the large eddy simulation of this type of flow. The numerical method used in the large eddy simulation must have low numerical dissipation and high order of accuracy. Compact methods which satisfy these requirements and have high resolution of frequency, are favorable ones for the large eddy simulation. A fourth-order compact finite volume method which had been developed in the MSc thesis of the author is extended and completed in the present work. This extension includes the...
Modeling of Liquid-Vapor Two Phase Flow through Nozzle
, M.Sc. Thesis Sharif University of Technology ; Nouri Borujerdi, Ali (Supervisor)
Abstract
This thesis is about modeling of liquid-vapor two phase flows through nozzle. Liquid-vapor two phase flow is very applicable in industries such as boilers, expansion valves, refrigeration and sudden failures in pipelines. Two models are used for modeling of fluid flow through nozzle, transient and steady state. In Both model the solution field is considered as saturated liquid and vapor and the mass, momentum and energy equations as well as equation of state is used for describing of fluid flow properties. Homogeneous equilibrium model is used and for complete modeling of fluid flow heat transfer and friction force is also considered.
Numerical solutions are used for solving of the...
Numerical solutions are used for solving of the...
Analyzing Fluid–Structure Interaction Problems in Compressible Flows
, Ph.D. Dissertation Sharif University of Technology ; Hejranfar, Kazem (Supervisor)
Abstract
The goal of this thesis is the development and application of the finite volume method (FVM) with a same solution procedure in the fluid and structure domains for the simulation of fluid-structure interaction (FSI) problems in the compressible fluid flow. The unsteady Euler equations written in the arbitrary Lagrangian–Eulerian (ALE) form are considered as the governing equations of the compressible fluid flow and the moderate/large nonlinear deformation of the elastic structure is considered to be governed by the Cauchy equations in the Lagrangian/total Lagrangian forms. Therefore, the nonlinear phenomena in the unsteady compressible fluid flow and the large deformation of the elastic...
Prediction of Hydraulic Fracturing Technology in Naturally Fractured Rocks, by Considering Immiscible Two-phase Flow
, Ph.D. Dissertation Sharif University of Technology ; Taghikhani, Vahid (Supervisor) ; Ayatollahi, Shahab (Supervisor) ; Shad, Saeed (Supervisor) ; Ranjbaran, Abdolrasul ($item.subfieldsMap.e)
Abstract
To have a deeper understanding of Hydraulic fracturing operation, in this study four important parts in this field was developed and simulated. In the first part, continuity and momentum equations for a single phase flow in a propagating penny-shaped fracture inside an impermeable matrix was revisited based on a fixed coordinate system. Its correctness was validated against experimental data and its features were compared with the well-known lubrication theory in analytical form. The new derived continuity equation caused the fracture tip to have a positive and finite pressure while, the conventional model predicted negative infinity for that. In the second part, Finite Volume method was...
Numerical Simulation of Landslide-Generated Tsunami Waves and the Slide Deformability
, Ph.D. Dissertation Sharif University of Technology ; Ataie-Ashtiani, Behzad (Supervisor)
Abstract
Potential landslides located in the borders of each water body may generate massive and destructive impulsive waves called landslide-generated waves (LGWs) which can be a major threat to human life and his possessions, offshore and coastal installations, dam bodies and hydraulic structures. This research is devoted to numerical modeling of LGW hazards with focus on the impulse wave generation stage including landslide movement, landslide/water surface interactions and consequent tsunami generation. The main purpose of this work is to study the effects of landslide deformability on the impulsive wave characteristics numerically in an introduced state-of-the-art numerical structure. The...
Solidification Simulation During Direct Metal Deposition of Functionally Graded Material
, M.Sc. Thesis Sharif University of Technology ; Akbari, Javad (Supervisor) ; Tavakoli, Roholla (Supervisor)
Abstract
Additive manufacturing can be considered as a revolution in the manufacturing industry. The unique capabilities of this technology have led to the removal of many obstacles to the construction of complex and special parts. In this study, with the aim of further understanding how the gradient region is formed, the possibility of detecting the microstructure and finally the properties of the gradient piece made, a solidification process has been simulated in direct metal deposition. The results of this study include calculating the heat distribution during the process and obtaining a thermal history of the fabricated part, calculating the dimensions of the molten pool and the heat affected...
A Study on Two-Phase Flow in Bottom Hole Conditions in Horizontal Wells
, M.Sc. Thesis Sharif University of Technology ; Shad, Saeed (Supervisor)
Abstract
Considering the importance of oil and gas industries in Iran, issues related to drilling and exploitation of oil and gas fields are among the country's priorities and challenges in industries, research centers and universities, and extensive research is conducted in this field. Since during the process of oil production from oil wells and reservoirs, the formation of multiphase flows, including two-phase fluid flow, is inevitable, investigating the behavior of multiphase fluids, which is a branch of fluid mechanics, is of special importance. In this regard, in continuation of the research conducted in the Faculty of Chemical and Petroleum Engineering of Sharif University of Technology, in...
Finite volume coupling strategies for the solution of a Biot consolidation model
, Article Computers and Geotechnics ; Vol. 55, issue , January , 2014 , p. 494-505 ; ISSN: 0266352X ; Ataie-Ashtiani, B ; Simmons, C. T ; Sharif University of Technology
Abstract
In this paper a finite volume (FV) numerical method is implemented to solve a Biot consolidation model with discontinuous coefficients. Our studies show that the FV scheme leads to a locally mass conservative approach which removes pressure oscillations especially along the interface between materials with different properties and yields higher accuracy for the flow and mechanics parameters. Then this numerical discretization is utilized to investigate different sequential strategies with various degrees of coupling including: iteratively, explicitly and loosely coupled methods. A comprehensive study is performed on the stability, accuracy and rate of convergence of all of these sequential...
Numerical investigation on the solid flow pattern in bubbling gas-solid fluidized beds: Effects of particle size and time averaging
, Article Powder Technology ; Vol. 264, issue , September , 2014 , p. 466-476 ; Salehi, M. S ; Molaei Dehkordi, A ; Sharif University of Technology
Abstract
The effects of particle size on the solid flow pattern in gas-solid bubbling fluidized beds were investigated numerically using two-fluid model based on the kinetic theory of granular flow. In this regard, the set of governing equations was solved using finite volume method in two-dimensional Cartesian coordinate system. Glass bead particles with mean sizes of 880. μm, 500. μm, and 351. μm were fluidized by air flow at excess gas velocities of 0.2. m/s and 0.4. m/s. For particle diameters of 880 and 351. μm, the predicted characteristic times for solid dispersion were 0.14. s and 0.15. s, respectively, while characteristic times for solid diffusivity were 1.68. ms and 0.75. ms in the same...
Reacting turbulent flow simulation to improve the mixing process in an oil refinery incinerator
, Article American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM ; Vol. 1C, issue , August , 2014 ; ISBN: 9780791846230 ; Abrar, B ; Barezban, M. B ; Faridvand, A ; Schneider, G. E ; Sharif University of Technology
Abstract
Combustion emission is one of the most important issues in the design of industries. Todays' strict environmental standards have limited the productions of CO, NOx, SOx, and other hazardous pollutants from the related industries. In this work, we study a typical oil refinery incinerator, which is used to burn waste gases residue produced during bitumen production process. The waste gas mainly includes a mixture including N2, H2O-vapor, and O2 species. Additionally, there are significant amounts of CO species and CxHy droplets in the waste gas composition. The measurements show that the CO emission becomes so crucial in high flow rate of feeding waste gas to the incinerator. Here, we...
Effects of viscoelastic polymer solutions on the oil extraction from dead ends
, Article Scientia Iranica ; Volume 20, Issue 6 , 2013 , Pages 1912-1920 ; 2345-3605 (e-ISSN) ; Ramazani, A. S. A ; Kamyabi, M. M ; Sharif University of Technology
Sharif University of Technology
2013
Abstract
This research deals with the numerical simulation of two viscoelastic uids ow in an open capillary of a reservoir. Oldroyd-B and Leonov models have been used to describe the rheological behavior of polymer solutions. The finite volume method on a structured and collocated grid has been used for discretization of the governing equations. The discrete elastic viscous stress splitting technique has also been used. The steady state, isothermal and incompressible uids past through a two dimensional micropore have been considered. The numerical method has been validated through the comparison of numerical results by the analytical solutions of Oldroyd-B uid ow through a planar channel. The effects...
Effect of porosity variation in determination of stagnant and dispersion thermal conductivities in the resin transfer molding process
, Article Heat Transfer Research ; Volume 43, Issue 7 , 2012 , Pages 651-667 ; 10642285 (ISSN) ; Rabani, R ; Kermani, M. J ; Sharif University of Technology
2012
Abstract
A numerical analysis for determination of the stagnant and dispersion thermal conductivities in the Resin Transfer Molding (RTM) process is presented. A solution was obtained for the momentum and energy equations, which are used in this study and which represent the Brinkman- Forchheimer-extended Darcy model, and one-temperature energy equation. Subject to the appropriate boundary conditions, the governing equations are solved by the finite volume method on a collocated grid. In order to satisfy the pressure-velocity coupling in the solution, the SIMPLE algorithm was used and for determining the mass flux flowing past the cell faces, the Rhie-Chow interpolation was applied. Both constant and...
Prediction and optimization of cure cycle of thick fiber-reinforced composite parts using dynamic artificial neural networks
, Article Journal of Reinforced Plastics and Composites ; Volume 31, Issue 18 , September , 2012 , Pages 1201-1215 ; 07316844 (ISSN) ; Shojaei, A ; Reza Pishvaie, S. M ; Sharif University of Technology
2012
Abstract
Curing of thermoset-based composites experience substantial temperature overshoot, especially at the center of thick parts and large temperature gradient exists through the whole part due to large amount of heat released and low conductivity of the composite. This leads to non-uniformity of cure, residual stress and consequently composite cracks and possibly degradation of the polymer. The scope of this work is to optimize the cure cycle in order to improve the properties and gaining a relatively uniform part of composite, using trained recurrent artificial neural networks purposed for speeding up the repetitious model re-calls during the optimization process. Numerical results obtained...
Simulation of turbulent swirling flow in convergent nozzles
, Article Scientia Iranica ; Volume 19, Issue 2 , 2012 , Pages 258-265 ; 10263098 (ISSN) ; Kebriaee, A ; Sharif University of Technology
Abstract
This work simulates the turbulent boundary layer of an incompressible viscous swirling flow through a conical chamber. To model the pressure gradient normal to the wall, the radial and tangential velocity components across the boundary layer have been calculated by both the integral and numerical methods. The numerical solution is accomplished by finite difference, based on the finite volume method. The results show that the radial and tangential boundary layer thicknesses depend on the velocity ratios, Reynolds number and nozzle angle. The peak of radial and tangential boundary layer thicknesses are located at zL≈0.2 and zL≈0.8 from the nozzle inlet, respectively. Due to the short length of...
Numerical investigation of thermo-fluid dynamics of two triangular jets
, Article Mechanika ; Volume 17, Issue 2 , 2011 , Pages 149-155 ; 13921207 (ISSN) ; Farhanieh, B ; Sharif University of Technology
2011
Abstract
This paper addresses the numerical simulation of thermo-fluid characteristics of triangular jets. The results of spatially developing, three dimensional jets from isosce-les and equilateral nozzles at different Reynolds numbers and distances between jets are presented. The system of governing equations, subject to the proper boundary condi-tions is solved with the finite volume method with collo-cated grid arrangement. SIMPLEC algorithm was used for the pressure-velocity coupling to discrete the governing equations of flow and energy. The turbulent stresses are approximated using k-ε model. The velocity and tempera-ture fields are presented and rates of their decay at jet cen-terline are...