Search for: three-dimensional-model
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    A numerical study on utilizing horizontal flat-panel ground heat exchangers in ground-coupled heat pumps

    , Article Renewable Energy ; Volume 147 , March , 2020 , Pages 996-1010 Habibi, M ; Amadeh, A ; Hakkaki Fard, A ; Sharif University of Technology
    Elsevier Ltd  2020
    Horizontal ground heat exchangers (GHEs) have a lower cost in comparison to vertical ones; however, they require more land area. For the sake of reducing the required land area for horizontal GHEs, flat-panel GHEs have been recently introduced. In this piece of research, a 3-D numerical model has been developed to predict the thermal performance of flat-panel GHEs. In this study, at first, the thermal performance of a flat-panel GHE has been compared with that of linear horizontal ones. The results demonstrate that the flat-panel GHE has a better thermal performance of about 27% in comparison to an arrangement of linear GHEs with a value of 0.5 m for pipe spacing. In the second part of this... 

    A year-round study of a photovoltaic thermal system integrated with phase change material in Shanghai using transient model

    , Article Energy Conversion and Management ; Volume 210 , 2020 Kazemian, A ; Salari, A ; Ma, T ; Sharif University of Technology
    Elsevier Ltd  2020
    In the study, the daily and monthly performance of a photovoltaic thermal system integrated with phase change material is investigated in Shanghai, China. A three-dimensional model of photovoltaic thermal system integrated with phase change material system is developed and numerically simulated. Water is considered as working fluid, and the fluid flow regime is laminar and incompressible. Both quasi-steady and transient models are compared together, and the transient model is selected because of its higher accuracy. Validation analysis is performed on the numerical model to show the reasonable agreement of current research compared to some other research. After obtaining the suitable... 

    Seismic performance evaluation of a novel bolted flush end-plate beam splice connection

    , Article Proceedings of the Institution of Civil Engineers: Structures and Buildings ; Volume 173, Issue 2 , 2020 , Pages 109-127 Keikha, H ; Mofid, M ; Sharif University of Technology
    ICE Publishing  2020
    This paper describes a three-dimensional (3D) finite-element (FE) model developed to assess the seismic behaviour of a novel prefabricated beam-to-beam connection termed a double-bolted flush end-plate beam (DBFEB) splice connection under cyclic loading. The seismic response was analysed and evaluated in terms of the hysteretic behaviour, rigidity, resistance degradation, ductility, energy dissipation capacity and equivalent damping coefficient. It is shown that the required performance can be achieved by controlling the end-plate thickness as well as the bolt grade and diameter; these parameters were therefore chosen as the key geometric variables investigated here for parametric study.... 

    A general multi-scale modeling framework for two-phase simulation of multi-stream plate-fin heat exchangers

    , Article International Journal of Heat and Mass Transfer ; Volume 156 , 2020 Niroomand, R ; Saidi, M. H ; Hannani, S. K ; Sharif University of Technology
    Elsevier Ltd  2020
    Compact heat exchangers are among the vital components used in various industries. In this study, a general framework has been developed with a multi-scale point of view for three-dimensional simulation of multi-stream plate-fin heat exchangers. The most important features in the MSPFHEs simulation, such as phase change phenomena, multi-component mixtures, multiple streams, transversal, lateral and longitudinal conduction, non-uniformity of inlet flow, variable fluid properties, and heat leakage are simultaneously considered in this model. The modular form of the model structure has facilitated layer-by-layer simulation of cross flow heat exchangers as well as parallel flow ones. Our model... 

    Coupled generative adversarial and auto-encoder neural networks to reconstruct three-dimensional multi-scale porous media

    , Article Journal of Petroleum Science and Engineering ; Volume 186 , 2020 Shams, R ; Masihi, M ; Boozarjomehry, R. B ; Blunt, M. J ; Sharif University of Technology
    Elsevier B.V  2020
    In this study, coupled Generative Adversarial and Auto-Encoder neural networks have been used to reconstruct realizations of three-dimensional porous media. The gradient-descent-based optimization method is used for training and stabilizing the neural networks. The multi-scale reconstruction has been conducted for both sandstone and carbonate samples from an Iranian oilfield. The sandstone contains inter and intra-grain porosity. The generative adversarial network predicts the inter-grain pores and the auto-encoder provides the generative adversarial network result with intra-grain pores (micro-porosity). Different matching criteria, including porosity, permeability, auto-correlation... 

    Numerical simulation of buoyancy affected turbulent air flow in a room

    , Article Scientia Iranica ; Volume 15, Issue 3 , 2008 , Pages 398-404 ; 10263098 (ISSN) Nouri Borujerdi, A ; Fathi Gishnegani, A ; Sharif University of Technology
    Sharif University of Technology  2008
    In this paper, a three-dimensional steady state incompressible turbulent air flow is considered in a large single room. The buoyancy affected turbulent air flow is numerically simulated by solving governing equations. The turbulence modeling includes both κ - ε and zero-equation models and their results are compared to the experimental data. The paper reviews several aspects, such as displacement of radiator system performance, temperature and flow field distribution and comfort conditions. The results show that the best temperature distribution and comfort condition are obtained when the radiator is installed under the window and its height is equal to or greater than that of the window. ©... 

    MODSharp: Regional-scale numerical model for quantifying groundwater flux and contaminant discharge into the coastal zone

    , Article Environmental Modelling and Software ; Volume 22, Issue 9 , 2007 , Pages 1307-1315 ; 13648152 (ISSN) Ataie Ashtiani, B ; Sharif University of Technology
    In this paper the development of a quasi-three-dimensional numerical model that can be used for quantifying groundwater inputs and associated contaminant discharged from coastal aquifers into the coastal zone at a regional scale is presented. The present model is called MODSharp. In order to handle problems at a regional scale, the sharp interface approach which is used for conceptualising seawater intrusion, is applied to this model. This model can be used for the simulation of groundwater flow and contaminant transport in layered coastal aquifers at a regional scale. The method of characteristics is used to solve the advection-dispersion equation, which governs contaminant transport in... 

    Effects of geometric imperfections on the performance of Sahand cooling tower

    , Article 10th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC 2010, Bangkok, 3 August 2006 through 5 August 2006 ; Volume 5 , 2006 , Pages 331-338 ; 9748257207 (ISBN); 9789748257204 (ISBN) Riahi, H. T ; Haghighi, B ; Sharif University of Technology
    School of Engineering and Technology  2006
    During construction of one of the Sahand cooling towers due to slip forming performance some imperfections were raised mostly between elevation of +30 and +40 meter. It was evaluated that some points of the shell should be repaired. In constructing the cooling tower from elevation +40 to +60 meter these imperfections were removed and the cooling tower was constructed with no problem until the elevation +130 meter. In this paper reasons of generation of geometric imperfections in Sahand cooling tower are clearly shown and possible ways for preventing them are discussed. Applied repairing method for Sahand cooling tower is explained in detail. Geometrical imperfections of the constructed... 

    Seismic behavior of a dolphin-type berth subjected to liquefaction induced lateral spreading: 1g large scale shake table testing and numerical simulations

    , Article Soil Dynamics and Earthquake Engineering ; Volume 140 , 2021 ; 02677261 (ISSN) Kavand, A ; Haeri, S. M ; Raisianzadeh, J ; Sadeghi Meibodi, A ; Afzal Soltani, S ; Sharif University of Technology
    Elsevier Ltd  2021
    The effects of liquefaction induced lateral spreading on the piles of a dolphin-type berth were investigated using 1 g large scale shake table testing accompanied by numerical simulations. For this purpose, various aspects of the response of the soil and the pile group to lateral spreading were considered. The results indicated that large bending moments were induced in the piles during lateral spreading and the downslope piles of the group received greater bending moments than the upslope one. The monotonic components of bending moments in the piles were reasonably predicted by the displacement based numerical approach using p-y springs when they were properly tuned for strength reduction... 

    Optimization of a novel photovoltaic thermal module in series with a solar collector using Taguchi based grey relational analysis

    , Article Solar Energy ; Volume 215 , 2021 , Pages 492-507 ; 0038092X (ISSN) Kazemian, A ; Parcheforosh, A ; Salari, A ; Ma, T ; Sharif University of Technology
    Elsevier Ltd  2021
    The solar collectors absorb solar irradiation and then produce thermal energy; however, they cannot generate electrical power. Electricity and thermal energy can be produced by the photovoltaic thermal module, simultaneously, while the outlet temperature of the photovoltaic thermal module is not usually high enough to provide thermal requirements of a building such as hot water or space heating. This work proposes a novel compound system created by the connection of a solar collector in series with a photovoltaic thermal module to resolve the issue of low outlet temperature in the photovoltaic thermal module and lack of electrical power in solar collectors. To examine the feasibility of this... 

    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) Savalanpour, H ; Farhanieh, B ; Afshin, H ; Sharif University of Technology
    Elsevier Ltd  2021
    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... 

    A hybrid of statistical and conditional generative adversarial neural network approaches for reconstruction of 3D porous media (ST-CGAN)

    , Article Advances in Water Resources ; Volume 158 , 2021 ; 03091708 (ISSN) Shams, R ; Masihi, M ; Bozorgmehry Boozarjomehry, R ; Blunt, M. J ; Sharif University of Technology
    Elsevier Ltd  2021
    A coupled statistical and conditional generative adversarial neural network is used for 3D reconstruction of both homogeneous and heterogeneous porous media from a single two-dimensional image. A statistical approach feeds the deep network with conditional data, and then the reconstruction is trained on a deep generative network. The conditional nature of the generative model helps in network stability and convergence which has been optimized through a gradient-descent-based optimization method. Moreover, this coupled approach allows the reconstruction of heterogeneous samples, a critical and serious challenge in conventional reconstruction methods. The main contribution of this work is to... 

    Experimental and theoretical evaluations of thermal histories and residual stresses in dissimilar friction stir welding of AA5086-AA6061

    , Article International Journal of Advanced Manufacturing Technology ; Volume 61, Issue 1-4 , 2012 , Pages 149-160 ; 02683768 (ISSN) Jamshidi Aval, H ; Serajzadeh, S ; Kokabi, A. H ; Sharif University of Technology
    In this work, the thermomechanical responses during the dissimilar friction stir welding of aluminum alloys have been evaluated employing a three-dimensional model and the finite element software ABAQUS. Furthermore, welding experiments have been conducted under different working conditions and the temperature variations during and after welding as well as the produced residual stresses in various positions of the welded samples were measured using hole-drilling technique. The model results were then examined by experimental data, and a reasonable agreement was observed. It is found that tool rotational speed significantly affects the amount of maximum tensile residual stress while traverse... 

    Assessment of a parallel evolutionary optimization approach for efficient management of coastal aquifers

    , Article Environmental Modelling and Software ; Volume 74 , December , 2015 , Pages 21-38 ; 13648152 (ISSN) Ketabchi, H ; Ataie Ashtiani, B ; Sharif University of Technology
    Elsevier Ltd  2015
    This study presents a parallel evolutionary optimization approach to determine optimal management strategies of large-scale coastal groundwater problems. The population loops of evolutionary algorithms (EA) are parallelized using shared memory parallelism to address the high computational demands of such applications. This methodology is applied to solve the management problems in an aquifer system in Kish Island, Iran using a three-dimensional density-dependent groundwater numerical model. EAs of continuous ant colony optimization (CACO), particle swarm optimization, and genetic algorithm are utilized to solve the optimization problems. By implementing the parallelization strategy, a... 

    CFD-DEM Model for Simulation of Non-spherical Particles in Hole Cleaning Process

    , Article Particulate Science and Technology ; Volume 33, Issue 5 , 2015 , Pages 472-481 ; 02726351 (ISSN) Akhshik, S ; Behzad, M ; Rajabi, M ; Sharif University of Technology
    Taylor and Francis Inc  2015
    During the well drilling process, particles are produced in different shapes. The shape of particles can influence the characteristics of particles transport process. The aim of this work is to analyze the effects of particle shape on the transportation mechanism. For this purpose, a three-dimensional model is prepared for simulation of particle transportation with spherical and non-spherical shapes, during deviated well drilling. The motion of particles and the non-Newtonian fluid flow are simulated via discrete element method and CFD, respectively. The two-way coupling scheme is used to incorporate the effects of fluid-particle interactions. Three different samples of non-spherical shapes... 

    3D Modeling of damage growth and crack initiation using adaptive finite element technique

    , Article Scientia Iranica ; Volume 17, Issue 5 A , 2010 , Pages 372-386 ; 10263098 (ISSN) Moslemi, H ; Khoei, A. R ; Sharif University of Technology
    In this paper, the continuum damage mechanics model originally proposed by Lemaitre (Journal of Engineering Materials and Technology. 1985; 107: 83-89) is presented through an adaptive finite element method for three-dimensional ductile materials. The macro-crack initiation-propagation criterion is used based on the distribution of damage variable in the continuum damage model. The microcrack closure effect is incorporated to simulate the damage evolution more realistic. The Zienkiewicz-Zhu posteriori error estimator is employed in conjunction with a weighted Superconvergence Patch Recovery (SPR) technique at each patch to improve the accuracy of error estimation and data transfer process.... 

    Three-dimensional simulation of turbulent flow in 3-sub channels of a VVER-1000 reactor

    , Article Scientia Iranica ; Volume 17, Issue 2 B , 2010 , Pages 83-92 ; 10263098 (ISSN) Ganjiani, H ; Firoozabadi, B ; Sharif University of Technology
    In this study, the fluid dynamics and convective heat transfer for turbulent flows through a 3-sub channel of a rod bundle, which is representative of those used in VVER-1000, are examined. The rod bundle is constructed from parallel rods in a hexagonal array. The rods are on constant pitch by spacer grids spaced axially along the rod bundle. The geometry details of the bundle and heat flux from the fuel rod are similar to that of the Iranian nuclear reactor under construction. A numerical study using Computational Fluid Dynamics (CFD) was carried out to estimate the flow field, pressure loss and heat transfer coefficients in spacer grids and rod bundles. Turbulence has been modeled using... 

    A physically-based three dimensional fracture network modeling technique

    , Article Scientia Iranica ; Volume 19, Issue 3 , 2012 , Pages 594-604 ; 10263098 (ISSN) Masihi, M ; Sobhani, M ; Al Ajmi, A. M ; Al Wahaibi, Y. M ; Khamis Al Wahaibi, T ; Sharif University of Technology
    In poorly developed fractured rocks, the contribution of individual fracture on rock conductivity should be considered. However, due to the lack of data, a deterministic approach cannot be used. The conventional way to model discrete fractures is to use a Poisson process, with prescribed distribution, for fracture size and orientation. Recently, a stochastic approach, based on the idea that the elastic energy due to fractures follows a Boltzmann distribution, has been used to generate realizations of correlated fractures in two dimensions. The elastic energy function has been derived by applying the appropriate physical laws in an elastic medium. The resulting energy function has been used... 

    CFD-DEM simulation of the hole cleaning process in a deviated well drilling: the effects of particle shape

    , Article Particuology ; Volume 25 , 2016 , Pages 72-82 ; 16742001 (ISSN) Akhshik, S ; Behzad, M ; Rajabi, M ; Sharif University of Technology
    We investigate the effect of particle shape on the transportation mechanism in well-drilling using a three-dimensional model that couples computational fluid dynamics (CFD) with the discrete element method (DEM). This numerical method allows us to incorporate the fluid-particle interactions (drag force, contact force, Saffman lift force, Magnus lift force, buoyancy force) using momentum exchange and the non-Newtonian behavior of the fluid. The interactions of particle-particle, particle-wall, and particle-drill pipe are taken into account with the Hertz-Mindlin model. We compare the transport of spheres with non-spherical particles (non-smooth sphere, disc, and cubic) constructed via the... 

    Investigating the effect of hybrid silica nanoparticles-copolymer on increasing oil recovery in a three dimensional porous media

    , Article Scientia Iranica ; Volume 24, Issue 6 , 2017 , Pages 3466-3475 ; 10263098 (ISSN) Golshokooh, S ; Ramazani, A. S. A ; Hekmatzadeh, M ; Sharif University of Technology
    In this work, hybrid of silica nanoparticles (NPs) with sulfonated copolymer has been prepared in order to improve the copolymer properties for Enhanced Oil Recovery (EOR). Some tests are done to find the effectiveness of injecting fluid on Recovery Factor (RF), such as Contact Angle (CA), interfacial tension (IFT), inherent viscosity, and eventually Micro-Model (MM) flooding. In CA test, wettability alteration from Oil-Wet (OW) to Water-Wet (WW) is reached by sedimentation and adsorption of NPs on the rock slice. In addition, IFT reduction is obtained by increasing the NaCl concentration. The viscosity change is investigated for the hybrid and copolymer under simulated high-temperature oil...