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finite-difference-method
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Total 169 records
Flow Simulation for Vacuum-assisted Resin Transfer Molding in Manufacturing of Composite Structures
, M.Sc. Thesis Sharif University of Technology ; Abedian, Ali (Supervisor)
Abstract
One of the common and efficient methods in the construction of large-scale structures from composites is the Vacuum Assisted Resin Transfer Molding (VARTM) method, which is widely used in the automotive industry, wind turbine blades, warships and pleasure boats, etc. VARTM is one of the liquid molding methods in which one side of the closed mold is replaced with a vacuum bag and the resin flows into the mold only with the help of air pressure (pressure of one atmosphere). One of the main challenges in the vacuum resin molding process is to be aware of the physics governing the flow motion in the porous mold so that the dry spots formed in the mold can be located accordingly. On the other...
Numerical Simulation of One-Dimensional Compressible Flow with Real Gas Effects by Solving Boltzmann Equation Using High-Order Accurate Finitedifference Method
, M.Sc. Thesis Sharif University of Technology ; Hejranfar, Kazem (Supervisor)
Abstract
In this study, the Shokov-BGK model of the Boltzmann equation is reformulated and generalized to consider the real gas effects. At first, the formulation is performed to consider an arbitrary specific heats ratio and the correct Prandtl number for polyatomic gases. Here, the resulting equations of the present formulation are numerically solved by applying the high-order finite-difference weighted essentially non-oscillatory (WENO) scheme. The present solution method is tested by computing the one-dimension Reiman problem with different specific heats ratios for a wide range of the Knudsen numbers. The results are compared with the available gas-kinetic results which show good agreement. It...
Numerical Modeling of Cone Penetration Tests in Saturated Clayey Soil under Undrained Conditions
, M.Sc. Thesis Sharif University of Technology ; Ahmadi، Mohammad Mehdi (Supervisor)
Abstract
This study aims to numerical modeling of piezocone penetration test (CPTu) in saturated clayey soils under undrained conditions using FLAC-2D software. According to the available studies, measuring excess pore water pressure during the piezocone penetration test can play an important role in determining the characteristics and engineering parameters of clayey soils. In many geotechnical problems, the initial state of existing stresses in the ground and are an important parameter that must be known for designs and analysis. The relationship between vertical and horizontal effective stress under zero lateral deformation is usually expressed by the coefficient of lateral earth pressure at...
Improving quality of service in 5G resilient communication with the cellular structure of smartphones
, Article ACM Transactions on Sensor Networks ; Volume 18, Issue 3 , 2022 ; 15504859 (ISSN) ; Javadpour, A ; Pinto, P ; Ja'Fari, F ; Zhang, W ; Sharif University of Technology
Association for Computing Machinery
2022
Abstract
Recent studies in information computation technology (ICT) are focusing on Next-generation networks, SDN (Software-defined networking), 5G, and 6G. Optimal working mode for device-to-device (D2D) communication is aimed at improving the quality of service with the frequency spectrum structure is of research areas in 5G. D2D communication working modes are selected to meet both the predefined system conditions and provide maximum throughput for the network. Due to the complexity of the direct solutions, we formulated the problem as an optimization problem and found the optimal working modes under different parameters of the system through extensive simulations. After determining the links'...
Development of subchannel thermal-hydraulic analysis code for dual cooled annular fuel
, Article Progress in Nuclear Energy ; Volume 150 , 2022 ; 01491970 (ISSN) ; Esmaili, H ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Regarding the geometric structural characteristics of innovative dual cooled annular fuel and the possibility of heat split and flow distribution among the internal and external channels, the development of new computational tools is essential for estimating safety margins and accurate assessment of its thermal-hydraulic performance. The SADAF code (Subchannel Analysis Dual cooled Annular Fuel) by COBRA-EN code is developed for this purpose. In the SADAF code, using COBRA-EN code for subchannel analysis in internal and external subchannels, a program has been developed to compute new variables that need to be considered in the thermal-hydraulic assessment. Also, fuel heat transfer...
Heat and mass transfer analysis and optimization of freeze desalination utilizing cold energy of LNG leaving a power generation cycle
, Article Desalination ; Volume 527 , 2022 ; 00119164 (ISSN) ; Eghtesad, A ; Afshin, H ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Freeze desalination (FD) works upon the separation of impurities from pure water during ice crystals formation. The required cold source could be supplied by the cold energy of liquefied natural gas (LNG). In the current study, freeze desalination of seawater is explored by directly exploiting the cold energy of LNG within an appropriate range of temperature after producing work in a power generation cycle. A detailed discussion has been given on the inlet temperature of LNG to the FD unit for the first time. The direct utilization has the privilege of eliminating the addition of a secondary refrigerant and its refrigeration cycle to the FD process. A multi-objective optimization is...
Simulation of proppant transport at intersection of hydraulic fracture and natural fracture of wellbores using CFD-DEM
, Article Particuology ; Volume 63 , 2022 , Pages 112-124 ; 16742001 (ISSN) ; Rajabi, M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Proppants transport is an advanced technique to improve the hydraulic fracture phenomenon, in order to promote the versatility of gas/oil reservoirs. A numerical simulation of proppants transport at both hydraulic fracture (HF) and natural fracture (NF) intersection is performed to provide a better understanding of key factors which cause, or contribute to proppants transport in HF–NF intersection. Computational fluid dynamics (CFD) in association with discrete element method (DEM) is used to model the complex interactions between proppant particles, host fluid medium and fractured walls. The effect of non-spherical geometry of particles is considered in this model, using the multi-sphere...
Magnetic field-induced control of a compound ferrofluid droplet deformation and breakup in shear flow using a hybrid lattice Boltzmann-finite difference method
, Article International Journal of Multiphase Flow ; Volume 146 , 2022 ; 03019322 (ISSN) ; Bijarchi, M. A ; Ghorbanpour Arani, A ; Rahimian, M. H ; Shafii, M. B ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
The deformation and breakup dynamics of a compound ferrofluid droplet under shear flow and uniform magnetic field are numerically studied in this paper. Utilizing magnetic field provides the possibility to obtain better control over the compound droplet morphology and breakup in a simple shear flow. To solve the governing equations for interfaces motion and hydrodynamics, the conservative phase field lattice Boltzmann model is employed, and a finite difference approach is applied for calculating the magnetic field. To verify the accuracy of present simulations, the results are validated with those of four relevant benchmarks including liquid lens between two stratified fluids, three-phase...
Computer simulation of the effect of particle stiffness coefficient on the particle-fluid flows
, Article Particulate Science and Technology ; Volume 40, Issue 2 , 2022 , Pages 233-242 ; 02726351 (ISSN) ; Rajabi, M ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
The Computational fluid dynamics (CFD)–discrete element method (DEM) numerical simulation may be applied to predict the hydrodynamic behavior of dense particle–fluid flows. The main drawback of this simulation is the long computational time required owing to the large number of particles and the minute time-step required to maintain a stable solution. In this work, a new method to improve the efficiency and accuracy of CFD–DEM simulations is presented. The particle stiffness coefficient is used as a flexible parameter to improve the accuracy and efficiency of the model. The particle concentration distribution results are compared with experimental one’s to derive the optimum effective...