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finite-volume-method
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Evaluation of a fourth-order finite-volume compact scheme for les with explicit filtering
, Article Numerical Heat Transfer, Part B: Fundamentals ; Volume 48, Issue 2 , 2005 , Pages 147-163 ; 10407790 (ISSN) ; Kazemzadeh Hannani, S. K ; Mashayek, F ; Sharif University of Technology
2005
Abstract
The accuracy of the large-eddy simulation (LES) of turbulent flows can be increased by using high-order numerical schemes in space and time, due to a decrease in numerical errors. This work investigates a high-order compact finite-volume scheme suitable for LES. The explicit fourth-order Runge-Kutta (RK) scheme for time marching and fourth-order compact schemes for spatial derivatives using a cell-averaged approach are implemented. Different subgrid-scale models and the effect of explicit filtering in a fully turbulent channel flow are studied. In this flow, the fourth-order compact finite-volume method in space, and fourth-order RK in time in conjunction with the dynamic Smagorinsky model...
A finite-volume-based lattice-Boltzmann method to simulate buoyant flow
, Article 43rd AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, 10 January 2005 through 13 January 2005 ; 2005 , Pages 2675-2684 ; Niavarani Kheiri, A ; Schneider, G. E ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2005
Abstract
Despite great advancement in the lattice Boltzmann method and its application in fluid flow problems, there are still major restrictions in treating either the solution domains with complex boundaries or buoyant flow problems. The past experience shows that the heat equation is a source for instabilities which jeopardizes the stable solution of the lattice Boltzmann method in solving fluid flow problems with heat transfer. The instabilities Increase with increasing buoyant force strength. In this work, we suggest a new approach to overcome the restrictions through implementing the advantages of finite volume method in LBM. In this regard, the lattice Boltzznann equation is incorporated with...
Implicit finite volume method to simulate reacting flow
, Article 43rd AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, 10 January 2005 through 13 January 2005 ; 2005 , Pages 7563-7573 ; Banaeizadeh, A ; Schneider, G. E ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc
2005
Abstract
In this work, an efficient bi-implicit strategy is suitably developed within the context of a finite volume element approach in order to solve turbulent reactive flow governing equations. Based on the essence of control-volume-based finite-element methods, the formulation retains the geometrical flexibility of the pure finite element methods while derives the discrete algebraic governing equations through using the conservation balance applied to discrete control volumes distributed all over the solution domain. The physical influence upwinding scheme is used to approximate the advection fluxes at all cell faces. While respecting the physics of flow, this scheme also provides the necessary...
Simulation of 2D fluid–structure interaction in inviscid compressible flows using a cell-vertex central difference finite volume method
, Article Journal of Fluids and Structures ; Volume 67 , 2016 , Pages 190-218 ; 08899746 (ISSN) ; Azampour, M. H ; Sharif University of Technology
Academic Press
Abstract
In the present study, the applicability and accuracy of a cell-vertex finite volume method developed are assessed in simulating 2D fluid–structure interaction in inviscid compressible flows where the nonlinear phenomena exist in both the unsteady transonic fluid flows and the large nonlinear deformation of solid structures. The unsteady Euler equations are considered as the governing equations of the fluid flow in the arbitrary Lagrangian–Eulerian form and the large nonlinear deformation of the solid structure is considered to be governed by the Cauchy equations in the total Lagrangian form. Both the domains are discretized by a second-order central-difference cell-vertex finite volume...
Numerical modeling of subsidence in saturated porous media: A mass conservative method
, Article Journal of Hydrology ; Volume 542 , 2016 , Pages 423-436 ; 00221694 (ISSN) ; Ataie Ashtiani, B ; Sharif University of Technology
Elsevier B.V
2016
Abstract
In this paper, a second order accurate cell-centered finite volume method (FVM) is coupled with a finite element method (FEM) to solve the deformation of a saturated porous layer based on Biot's consolidation model. The proposed numerical technique is applied to the fully unstructured triangular grids to simulate actual geological formations. To reconstruct the pressure gradient at control volume faces, the diamond scheme is implemented as a multipoint flux approximation method. Also the least square algorithm is used to interpolate pressure at the vertices from the cell-center values. The stability of this numerical model is studied in comparison to the different FEMs through various...
On spatial filtering of flow variables in high-order finite volume methods
, Article Computers and Fluids ; Volume 132 , 2016 , Pages 19-31 ; 00457930 (ISSN) ; Farshchi, M ; Hejranfar, K ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
A new method of spatial filtering in high-order finite volume methods is presented and assessed. The base of this method is to filter face-averaged variables (fluxes) and then the recovery of cell-averaged ones. Two kinds of filtering method are proposed. The first kind is highly dissipative and appropriate for the numerical regions that need high dissipation, e.g. sponge zones. The second kind, on the other hand, is a precise method and hence is suitable for applying the high-order finite difference filters to the finite volume methods. Applying high-order finite difference filters directly to the high-order finite volume methods without using the proposed method causes stability problems...
An inverse problem method for gas temperature estimation in partially filled rotating cylinders
, Article Scientia Iranica ; Volume 15, Issue 5 , 2008 , Pages 584-595 ; 10263098 (ISSN) ; Farhanieh, B ; Sharif University of Technology
Sharif University of Technology
2008
Abstract
The objective of this article is to study gas temperature estimation in a partially filled rotating cylinder. From the measured temperatures on the shell, an inverse analysis is presented for estimating the gas temperature in an arbitrary cross-section of the aforementioned system. A finite-volume method is employed to solve the direct problem. By minimizing the objective function, a hybrid effective algorithm, which contains a local optimization algorithm, is adopted to estimate the unknown parameter. The measured data are simulated by adding random errors to the exact solution. The effects of measurement errors on the accuracy of the inverse analysis are investigated. Two optimization...
Numerical Simulation of Two-dimensional Compressible Flow by Central Difference Finite Volume Scheme and Immersed Boundary Method
, M.Sc. Thesis Sharif University of Technology ; Hejranfar, Kazem (Supervisor)
Abstract
In this study,thecut-cells method is developed for simulating two-dimensional, inviscid, compressible flows with immersed boundaries. A finite volume method based on the second-order accurate central-difference scheme and the Runge-Kutta time stepping scheme is used. The key aspects that require to be considered in thedevelopment of such a solver are implementation of boundary conditions on the immersed boundaries and correct discretizing the governing equations in those cells cut by the boundaries. An appropriate interpolation procedure is applied to preserve the second-order spatial accuracy of the solver. The solution procedure is validated vs. well documented test problems for a wide...
Numerical Modeling of Reformer in Direct Reduction Plants
, M.Sc. Thesis Sharif University of Technology ; Afshin, Hossein (Supervisor) ; Farhanieh, Bijan (Supervisor)
Abstract
Direct reduction of iron is a process to reduce iron in solid phase. The output of this procedure is direct reduced iron (DRI) that can be used in electric arc furnacewithout further changes. Midrex technology, which is the most important one among direct reduction of iron processes, provides 60% of DRI.
Required synthesis gas for reduction process is gained from reforming of the natural gas,with the major proportion of methane, with water steam and carbon dioxide in a piece of equipment called “reformer”. As a matter of fact, reformer is a type of plug chemical reactors. Input materials (natural gas, water steam and carbon dioxide) enter from the bottom section to the prepared pipes in...
Required synthesis gas for reduction process is gained from reforming of the natural gas,with the major proportion of methane, with water steam and carbon dioxide in a piece of equipment called “reformer”. As a matter of fact, reformer is a type of plug chemical reactors. Input materials (natural gas, water steam and carbon dioxide) enter from the bottom section to the prepared pipes in...
Unsteady Aerodynamic Simulation of Horizontal Axis Wind Turbine (HAWT)
, M.Sc. Thesis Sharif University of Technology ; Abbaspour, Madjid (Supervisor) ; Soltani, Mohamad Reza (Co-Advisor)
Abstract
The ultimate aim of this research is optimizing high- performance Horizontal Axis Wind Turbine (HAWT) associated with using Computational fluid dynamics (CFD) to predict the flow behavior over wind turbine blades. Computational prediction of the flow over wind turbines is a challenging numerical problem because of the complicated aerodynamics and large variation in length scales. Phenomena such as; the unsteady flow, vortex shedding of the blade tips, flow separation, complicated blade geometry due to variable twist and chord and changes in angle of attack, and highly turbulent flow over blade sections makes CFD prediction challenging, as well as interesting. The goal is to gain an in depth...
Numerical Solution of Flow and Heat Transfer in Micro Heat Pipes
, M.Sc. Thesis Sharif University of Technology ; Farhanieh, Bijan (Supervisor) ; Afshin, Hossein (Co-Advisor)
Abstract
One of the important issues that increasing development of electronic systems has caused is how to transfer the generated heat out of the system. Heat pipes can transfer large amount of heat because of using latent heat of evaporation and condensation. In micro scales using micro heat pipes is popular that in this instrument liquid returns to evaporator by means of surface tension force. So numerical solution is essential for verifying experimental results and increasing performance of this instrument. In this research has been planned to develop a comprehensive model for numerical solution of flow and heat transfer in micro heat pipes. For this reason surface evaporation and …,...
A Unified Fve-Ale Approach to Solve Unsteady Laminar to Turbulent Flow on Moving Boundary Domains
, Ph.D. Dissertation Sharif University of Technology ; Darbandi, Masoud (Supervisor) ; Taeibi Rahni, Mohammad (Supervisor)
Abstract
In this study, an arbitrary Lagrangian-Eulerian (ALE) approach is incorporated with a mixed finite- volume-element (FVE) method to establish a novel moving boundary algorithm to simulate unsteady incompressible flow on non-stationary meshes. The method collects the advantages of both finite-volume and finite-element methods as well as the ALE approach in a unified algorithm capable of solving laminar, transient, and turbulent flows in fluid flow problems with moving boundaries. To enhance the robustness of the extended algorithm, we treat the convection terms at the cell faces using a physical influence upwinding scheme, while the diffusion terms are treated using bilinear finite-element...
Harness Aquatic Clean Energy from Vortex Induced Vibration
, M.Sc. Thesis Sharif University of Technology ; Abbaspour, Madjid (Supervisor) ; Afshin, Hossein (Co-Advisor)
Abstract
Transverse Vortex-Induced Vibration(VIV) and Flow-Induced Vibration(FIV) of a rigid, circular, elastically mounted single degree of freedom cylinder is scrutinized in range 3×104≤ Re ≤12×104 by means of Computational Fluid Dynamics(CFD). ANSYS CFX, based on FV, is employed to simulate VIV and FIV in different system parameters such as stiffness and mass ratio. Firstly, the minimum structured, hexahedron computational cell required to simulate VIV and FIV by means of Finite Volume (FV) method is provided. Then, the appropriate size for computational domain to simulate VIV and FIV accurately is discussed concisely. Approximated amplitude and frequency ratio are compared to experimental data...
Simulation of Advection and Diffusion of Hazardous Noxious Substances (HNS) in Sea, Case Study: Oil Derivations in Caspian Sea
, M.Sc. Thesis Sharif University of Technology ; Raie, Mohammad (Supervisor)
Abstract
Hazardous Noxious Substances (HNS) are chemicals. Due to population increase and as a result, increased demand, HNS transportation by sea has been raised. Gasoline and diesel are two kinds of HNS which have the largest transported amount via northern ports of Iran especially Anzali port. So, HNS spill from tankers is an imminent event and threat for environment of Caspian Sea. Organizations that are concern about the health of coasts and seas water always try to use the softwares to simulate the currents and waves to define the hydrocarbon slick transport. Therfore in this study, a 2D hydrodynamic/oil spill model has been developed to predict the transportation of diesel and gasoline slick...
Numerical Modeling of Subsidence Using Finite Volume Method
, Ph.D. Dissertation Sharif University of Technology ; Ataie Ashtiani, Behzad (Supervisor)
Abstract
In this study a locally mass conservative finite volume method (FVM) is employed to simulate the coupled model of flow and geomechanics for the land subsidence problem. At the first step, a FV numerical method is implemented to solve a Biot consolidation model with discontinuous coefficients one dimensionally. The 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...
Numerical and One Dimensional Modeling of Cardiovascular System
,
M.Sc. Thesis
Sharif University of Technology
;
Saeedi, Mohammad Saeed
(Supervisor)
;
Firoozabadi, Bahar
(Supervisor)
Abstract
Cardiovascular diseases are most common causes of deaths in the whole world. Nowadays, engineers and scientists in various fields become intent on finding solutions for prevention and recovery of these diseases. In this way, it is very important to know about the blood flow in arterial systems and its changes in various diseases. Numerical simulation of the blood flow beside of experimental studies could be very useful in this way. One dimensional simulation among various methods of numerical simulation was chosen to simulate a cardiovascular system since it has smaller computational cost and ability to modeling of whole arterial systems. It also is useful in extraction of medical indexes....
Simulation of Behavior of a Single Cavitating Bubble Near Solid Boundariesby solvingTwophase Navier-Stokes Equations with a Central Difference Finite Volume Method
, M.Sc. Thesis Sharif University of Technology ; Hejranfar, Kazem (Supervisor)
Abstract
In the present work, the deformation and collapse of a single cavitating bubble near solid boundaries is simulated by solving the preconditioned, homogenous, multiphaseNavier-Stokes equations. Up to now, all studies in the literature performed by the volume of fluid (VOF)approach to capture the bubble surface have been based on the pressure-based category in which the flow variables are calculated through solving the Poisson equation. Here, the density-based category is applied and the solution methodology is based on the artificial compressibility approach. The compressible form of the Navier-Stokes equations is applied inside the bubble and the liquid phase is assumed to be incompressible....
Hydrodynamic Investigation of Manta Ray MotionUsing Numerical Methods
, M.Sc. Thesis Sharif University of Technology ; Abbaspour, Majid (Supervisor)
Abstract
The idea of using under water vehicles inspired by nature has gained considerable attention during the past few decades. This interest is due to the advantages of swimming and moving by this technique, in comparison with the conventional methods. Benefits are such as increasing speed, improved power, better manoeuvre ability,greater stability, optimal hydrodynamic performance ... etc. The purpose of this study was developing a model to simulate a stingray Manta Ray moving behaviour. Ansys- Fluent software was applied to solve the related equations of viscous laminar flow in 3-D form.Simulation of Manta Ray was performed with the flapping pectoral fin with dynamic mesh. Using this...
Vibration Analysis of Dolid-Fluid Interaction to Improve the Aerodynamic Performance of Airfoils with Deflectable Skins
, M.Sc. Thesis Sharif University of Technology ; Darbandi, Masoud (Supervisor)
Abstract
Progress aerodynamic and structural applications has lead to solid-fluid interaction (SFI) engineering. One major application of SFI is to improve of aerodynamic characteristics of airplanes. One option is to use elastic shells.this field of study is so novel and a challenge for future researches. This what current thesis is focused on We use numerical simulation in both fluid and solid parts.In other word, we employ the finite –element method to solve the solid mechanics governing equation and the finite volume element method to treat the fluid dynamics governing equations. The fluid governing equations are 2D navier- stokes equations and the solid part is the 1D Euler – Bernoulli equations...
Numerical Simulation of Turbulent Cavitating Flows Using Two-Equation k-ϵ Turbulence Model
, M.Sc. Thesis Sharif University of Technology ; Hejranfar, Kazem (Supervisor)
Abstract
In the current study, the numerical simulation of the turbulent cavitating flows is performed by solving the preconditioned, homogenous, multiphase Navier-Stokes equations. For the turbulence modeling, the standard two-equation k-ϵ model is used. The baseline differential equations system is comprised of the mixture volume, mixture momentum and constituent volume fraction equations together with two equations for the turbulence kinetic energy k and the turbulence energy dissipation rate ϵ. For the calculation of the eddy viscosity near the wall boundary, appropriate turbulence damping functions are applied to modify the source terms of the ϵ equation. The system of governing equations is...