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volume-of-fluid
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Total 47 records
Numerical Simulation of Hydrodynamics of Flow over Gabion Stepped Weir
, M.Sc. Thesis Sharif University of Technology ; Shamsai, Abolfazl (Supervisor) ; Ghaemian, Mohsen (Co-Supervisor)
Abstract
The use of stepped weirs dates back at least 3500 years. In this research, the hydrodynamics of gabion stepped weirs have been investigated as a three-dimensional simulation of two-phase flow air-water using Flow3D software and the method of computational fluid dynamics (CFD) analysis. In order to solve the Reynolds-Averaged Navier-Stokes (RANS) equations, the RNG turbulence model (k-ε) was used and the free surface elevation of fluid was determined by the volume of fluid (VOF) method. The experimental results of Wutrish and Chanson (2014) over gabion stepped weirs are used to validate the numerical model simulations. Gabion stepped weirs with steps of 3, 7.5, and 10 cm in height, as well as...
Analysis of Factors Affecting Cavitation of Ogee Crested Spillway in Concrete Dams
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
In this study, the factors affecting cavitation in the crest of an ogee spillway were investigated. One of the factors affecting the occurrence of cavitation on the ogee crest is the ratio of the head to the design head. As the head ratio increases, the probability of cavitation on the crest increases. The value of the head is also an effective parameter for the occurrence of cavitation. The spillway crest curve is also one of the factors affecting the occurrence of cavitation on the ogee-crested spillways. In this study, the ogee crested spillway that consists of three circular arcs upstream has been investigated. 5 different head ratios have been used. For this study, OpenFOAM software,...
Simulation of incompressible multiphase flows using the artificial compressibility method
, Article ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting, FEDSM 2018, 15 July 2018 through 20 July 2018 ; Volume 2 , 2018 ; 08888116 (ISSN); 9780791851562 (ISBN) ; Hejranfar, K ; Fluids Engineering Division ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2018
Abstract
The Eulerian methods are susceptible to generate the nonphysical spurious currents in the multiphase flow simulations near the interfaces. This paper presents a new Eulerian method to accurately simulate the velocity fields, especially near the multiphase flow interfaces and prevents the numerical results from generating the nonphysical currents. A Eulerian central difference finite-volume scheme equipped with the suitable numerical dissipation terms is used to simulate incompressible multiphase flows. The interface is captured by Flux Corrected Transport-Volume of Fluid method (FCT-VOF). Increasing the accuracy near the sharp gradients, such as interface, the conservative form of...
Optimization of microgrooves for water–solid drag reduction using genetic algorithm
, Article Journal of Ocean Engineering and Marine Energy ; Volume 6, Issue 3 , 2020 , Pages 221-242 ; Moosavi, A ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2020
Abstract
The friction on the water–solid interfaces continues to be the most important factor for the energy loss in many marine and submarine applications. Therefore, different techniques have been developed and are available to reduce friction and, as a result, the overall cost. In the past decades, the use of structured surfaces has been given considerable attention because of their specific characteristics such as their abilities in pressure drop reduction. However, an appropriate optimization method is required to find the best surface structure. In the present study, we consider a microgrooved substrate and examine the performance of three shapes including rectangular, elliptical, and...
Modelling of foam degradation in lost foam casting process
, Article Materials and Design ; Volume 27, Issue 2 , 2006 , Pages 115-124 ; 02613069 (ISSN) ; Serajzadeh, S ; Varahram, N ; Davami, P ; Sharif University of Technology
Elsevier Ltd
2006
Abstract
In this study, a new model was developed to calculate gas pressure at the melt/foam interface due to foam degradation during mould filling in the lost foam casting process. Different aspects of the process, such as foam degradation, gas elimination, and permeability of the refractory coating, were incorporated into this model. A computational fluid dynamic code was developed based on the numerical technique of the solution algorithm-volume of fluid (SOLA-VOF) for the simulation and prediction of the melt flow. In order to verify the computational results of the simulation, a thin plate of grey iron at 1350 °C was poured into a transparent foam mould. The mould filling process was recorded...
Two phase gas-liquid bubbly flow modeling in vertical mini pipe
, Article 2010 14th International Heat Transfer Conference, IHTC 14, 8 August 2010 through 13 August 2010 ; Volume 3 , 2010 , Pages 947-956 ; 9780791849385 (ISBN) ; Karabi, H ; Khorsandi, S ; Saidi, M. H ; Heat Transfer Division ; Sharif University of Technology
Abstract
Studies on two-phase flow in small scale pipes have become more important, because of the application of mini-scale devices in several engineering fields including, high heat-flux compact heat exchangers, and cooling systems of various types of equipment. In a mini pipe the behavior of two phase flow is not the same as flow in conventional pipes. The difference is caused by different effective forces; for e. g. inside a mini pipe capillary forces are more important in comparison with gravitational forces. This paper is devoted to numerical simulation of gas-liquid two phase flow in a vertical mini pipe. Prediction of bubble shape and the effects of gas and liquid velocities on flow...
Towards simulation of 3D nonlinear high-speed vessels motion
, Article Ocean Engineering ; Volume 36, Issue 3-4 , 2009 , Pages 256-265 ; 00298018 (ISSN) ; Jahanbakhsh, E ; Seif, M. S ; Sharif University of Technology
2009
Abstract
A numerical simulation algorithm based on the finite volume discretisation is presented for analyzing ship motions. The algorithm employs a fractional step method to deal with the coupling between the pressure and velocity fields. The free surface capturing is fulfilled by using a volume of fluid method in which the interface between the liquid (water) and gas (air) phases are computed by solving a scalar transport equation for the volume fraction of the liquid phase. The computed velocity field is employed to evaluate the acting forces and moments on the vessel. Using the strategy of boundary-fitted body-attached mesh and calculating all six degrees-of-freedom of motion in each time step,...