Search for: flow-of-fluids
0.014 seconds
Total 207 records

    New correlative models to improve prediction of fracture permeability and inertial resistance coefficient

    , Article Transport in Porous Media ; Volume 121, Issue 3 , February , 2018 , Pages 557-584 ; 01693913 (ISSN) Foroughi, S ; Jamshidi, S ; Pishvaie, M. R ; Sharif University of Technology
    Springer Netherlands  2018
    Presence of fracture roughness and occurrence of nonlinear flow complicate fluid flow through rock fractures. This paper presents a qualitative and quantitative study on the effects of fracture wall surface roughness on flow behavior using direct flow simulation on artificial fractures. Previous studies have highlighted the importance of roughness on linear and nonlinear flow through rock fractures. Therefore, considering fracture roughness to propose models for the linear and nonlinear flow parameters seems to be necessary. In the current report, lattice Boltzmann method is used to numerically simulate fluid flow through different fracture realizations. Flow simulations are conducted over a... 

    A three-dimensional mesh-free model for analyzing multi-phase flow in deforming porous media

    , Article Meccanica ; Volume 51, Issue 3 , 2016 , Pages 517-536 ; 00256455 (ISSN) Samimi, S ; Pak, A ; Sharif University of Technology
    Springer Netherlands 
    Fully coupled flow-deformation analysis of deformable multiphase porous media saturated by several immiscible fluids has attracted the attention of researchers in widely different fields of engineering. This paper presents a new numerical tool to simulate the complicated process of two-phase fluid flow through deforming porous materials using a mesh-free technique, called element-free Galerkin (EFG) method. The numerical treatment of the governing partial differential equations involving the equilibrium and continuity equations of pore fluids is based on Galerkin’s weighted residual approach and employing the penalty method to introduce the essential boundary conditions into the weak forms.... 

    Study of the effect of thermal dispersion on internal natural convection in porous media using fourier series

    , Article Transport in Porous Media ; Volume 131, Issue 2 , 2020 , Pages 537-568 Fahs, M ; Graf, T ; Tran, T. V ; Ataie Ashtiani, B ; Simmons, C. T ; Younes, A ; Sharif University of Technology
    Springer  2020
    Natural convection in a porous enclosure in the presence of thermal dispersion is investigated. The Fourier–Galerkin (FG) spectral element method is adapted to solve the coupled equations of Darcy’s flow and heat transfer with a full velocity-dependent dispersion tensor, employing the stream function formulation. A sound implementation of the FG method is developed to obtain accurate solutions within affordable computational costs. In the spectral space, the stream function is expressed analytically in terms of temperature, and the spectral system is solved using temperature as the primary unknown. The FG method is compared to finite element solutions obtained using an in-house code... 

    A neumerical method to investigate the effect of ultrasonic waves on capillary imbibition

    , Article 72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010 ; Volume 5 , 2010 , Pages 3246-3250 ; 9781617386671 (ISBN) Keshavarzi, B ; Karimi, R ; Najafi, I ; Ghotbi, C ; Ghaedian, M ; Sharif University of Technology
    Society of Petroleum Engineers  2010
    A lot of laboratory experiments have been carried out to investigate each aspect of ultrasonic wave s role on fluid flow behavior through porous media. Despite all experimental works, little attention has been paid for modeling the ultrasonic wave influence on capillary imbibition, which is the main mechanism of production in fractured reservoirs. At this work the process of imbibition with and without applying ultrasonic waves is mathematically modeled by modification of piston-like model. In contrast to this model s assumption, in which mobility ratio is assumed to be constant, here permeability variation due to increase in water saturation is considered in numerical solution. To evaluate... 

    Conceptual duct shape design for horizontal-axis hydrokinetic turbines

    , Article Scientia Iranica ; Volume 23, Issue 5 , 2016 , Pages 2113-2124 ; 10263098 (ISSN) Zahedinejad, A ; Rad, M ; Khayat, M ; Sharif University of Technology
    Sharif University of Technology  2016
    In the present paper, conceptual duct shape design for kinetic energy extraction with hydrokinetic turbines is discussed. The goal is to find a single-passage axisymmetric geometry that holds stable flow with maximum kinetic energy flux at duct throat. For finding the optimum duct shape, the fluid flow was numerically simulated in a wedge shaped space with Flow-Simulation Software. In a multi-stage conceptual design, tabulated configurations were employed to study each geometrical characteristic separately. These include curvature of profile camber, trailing edge shape, profile tip shape, and duct exit cross sectional area. The revolved profile of each duct consists of a well constrained... 

    Introducing a new definition towards clinical detection of microvascular changes using diffusion and perfusion MRI

    , Article Scientia Iranica ; Volume 12, Issue 1 , 2005 , Pages 109-115 ; 10263098 (ISSN) Ashoor, M ; Jiang, Q ; Chopp, M ; Jahed, M ; Sharif University of Technology
    Sharif University of Technology  2005
    Based on MRI diffusion and perfusion, a new criterion for detection and the healing progress of damaged tissue is suggested. The study is based on the ratio of capillary radii in symmetrical damaged and normal tissue neighboring spaces. The Apparent Diffusion Coefficient (ADC) and Cerebral Blood Flow (CBF) were measured in the brain tissues of six male Wistar rats utilizing suggested MRI measurement techniques. The ADC values of damaged and normal regions were (392 ± 34.1) × 10-6 mm2s-1 and (659 ± 40.7) × 10-6 mm2s-1, respectively. The CBF values of damaged and normal regions were 14.5 ± 10.13 ml/min/ 100 g and 125 ± 41.03 ml/min/100 g, respectively. The geometrical parameters of the... 

    Computation of three-dimensional supersonic turbulent flows over wrap-around fin projectiles using personal computers

    , Article Scientia Iranica ; Volume 12, Issue 2 , 2005 , Pages 217-228 ; 10263098 (ISSN) Fazeli, H ; Azimi, A ; Farhanieh, B ; Sharif University of Technology
    Sharif University of Technology  2005
    The three-dimensional supersonic turbulent flows over wrap-around fin missiles have been computed using the Thin Layer Navier-Stokes (TLNS) equations to reduce the computational efforts compared to those of the Full Navier-Stokes (FNS) equations. In this research, the missile configuration is divided into multi regions to enable fluid flow simulation using Personal Computers (PC). It also makes it possible to use a different number of nodes and distribution of grids in each region to enhance the accuracy. The Thin Layer Navier-Stokes equations in the generalized coordinate system were solved using an efficient, implicit, finite-difference factored algorithm of the Beam and Warming. For the... 

    Computational modeling of media flow through perfusion-based bioreactors for bone tissue engineering

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 234, Issue 12 , 2020 , Pages 1397-1408 Nokhbatolfoghahaei, H ; Bohlouli, M ; Adavi, K ; Paknejad, Z ; Rezai Rad, M ; khani, M. M ; Salehi-Nik, N ; Khojasteh, A ; Sharif University of Technology
    SAGE Publications Ltd  2020
    Bioreactor system has been used in bone tissue engineering in order to simulate dynamic nature of bone tissue environments. Perfusion bioreactors have been reported as the most efficient types of shear-loading bioreactor. Also, combination of forces, such as rotation plus perfusion, has been reported to enhance cell growth and osteogenic differentiation. Mathematical modeling using sophisticated infrastructure processes could be helpful and streamline the development of functional grafts by estimating and defining an effective range of bioreactor settings for better augmentation of tissue engineering. This study is aimed to conduct computational modeling for newly designed bioreactors in... 

    Prediction of necrotic core and hypoxic zone of multicellular spheroids in a microbioreactor with a U-shaped barrier

    , Article Micromachines ; Volume 9, Issue 3 , 2018 ; 2072666X (ISSN) Barisam, M ; Saidi, M. S ; Kashaninejad, N ; Nguyen, N. T ; Sharif University of Technology
    MDPI AG  2018
    Microfluidic devices have been widely used for biological and cellular studies. Microbioreactors for three-dimensional (3D) multicellular spheroid culture are now considered as the next generation in in vitro diagnostic tools. The feasibility of using 3D cell aggregates to form multicellular spheroids in a microbioreactor with U-shaped barriers has been demonstrated experimentally. A barrier array is an alternative to commonly used microwell traps. The present study investigates oxygen and glucose concentration distributions as key parameters in a U-shaped array microbioreactor using finite element simulation. The effect of spheroid diameter, inlet concentration and flow rate of the medium... 

    Design of a hybrid inertial and magnetophoretic microfluidic device for ctcs separation from blood

    , Article Micromachines ; Volume 12, Issue 8 , 2021 ; 2072666X (ISSN) Nasiri, R ; Shamloo, A ; Akbari, J ; Sharif University of Technology
    MDPI AG  2021
    Circulating tumor cells (CTCs) isolation from a blood sample plays an important role in cancer diagnosis and treatment. Microfluidics offers a great potential for cancer cell separation from the blood. Among the microfluidic-based methods for CTC separation, the inertial method as a passive method and magnetic method as an active method are two efficient well-established methods. Here, we investigated the combination of these two methods to separate CTCs from a blood sample in a single chip. Firstly, numerical simulations were performed to analyze the fluid flow within the proposed channel, and the particle trajectories within the inertial cell separation unit were investigated to... 

    A characteristic-based numerical simulation of water-titanium dioxide nano-fluid in closed domains

    , Article International Journal of Engineering, Transactions A: Basics ; Volume 33, Issue 1 , 2020 , Pages 158-163 Adibi, T ; Razavi, S. E ; Adibi, O ; Sharif University of Technology
    Materials and Energy Research Center  2020
    A new characteristic-based method is developed and used for solving the mixed and forced convection problems. The nano-fluid flow with heat transfer is simulated with a novel characteristic-based scheme in closed domains with different aspect ratios. For this purpose, a FORTRAN code has been written and developed. Water as a pure fluid and water-titanium dioxide as a nano-fluid were considered. The governing equations are solved by the finite volume utilizing a characteristic-based scheme for the convective fluxes. The simulation is done at Grashof numbers from 100 to 104, Reynolds numbers from 100 to 1000, and volume fractions of nano-particles from 0% to 10%. Streamlines, isotherms,... 

    Hydrodynamics analysis of Density currents

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 21, Issue 3 , 2008 , Pages 211-226 ; 1728-144X (ISSN) Afshin, H ; Firoozabadi, B ; Rad, M ; Sharif University of Technology
    Materials and Energy Research Center  2008
    Density Current is formed when a fluid with heavier density than the surrounding fluid flows down an inclined bed. These types of flows are common in nature and can be produced by; salinity, temperature inhomogeneities, or suspended particles of silt and clay. Driven by the density difference between inflow and clear water in reservoirs, density current plunges clear water and moves towards a dam, while density current flows on a sloping bed. The vertical spreading due to water entrainment has an important role in determining the propagation rate in the longitudinal direction. In this work, two-dimensional steady-state salt solutions' density currents were investigated by means of... 

    Nonlinear analysis of 2D flexible flapping wings

    , Article Nonlinear Dynamics ; Volume 81, Issue 1-2 , July , 2015 , Pages 299-310 ; 0924090X (ISSN) Abedinnasab, M. H ; Zohoor, H ; Yoon, Yong Jin ; Sharif University of Technology
    Kluwer Academic Publishers  2015
    Natural flyers have flexible wings, which deform significantly under the combined inertial and aerodynamic forces. In this study, we focus on the role of chord wise flexibility in 2D pitch and plunge motions. We derive the exact nonlinear 2D equations of motion for a flexible flapping wing with flying support. In achieving the closed-form equations, we use the exact strain field concerning considerable elastic deformations. After numerically solving the novel equations, we validate them in simulations with highly deformable wings. By coupling the derived equations of motion with fluid flow, we study the aerodynamic performance of the geometrically nonlinear flexible flapping wing. Through... 

    Stress-jump and Continuity Interface Conditions for a Cylinder Embedded in a Porous Medium

    , Article Transport in Porous Media ; Volume 107, Issue 1 , 2015 , Pages 171-186 ; 01693913 (ISSN) Rashidi, S ; Nouri Borujerdi, A ; Valipour, M. S ; Ellahi, R ; Pop, I ; Sharif University of Technology
    Kluwer Academic Publishers  2015
    The selection of interface boundary conditions between porous-medium and clear-fluid regions is very important for the wide range of engineering applications. In this paper, the difference between two common types of fluid flow interfacial conditions between clear fluid and porous medium is analyzed in detail. These two types of fluid flow interfacial condition are stress-jump and stress-continuity conditions. The effects of porosity on these types of interface condition are studied. The results are presented for different Reynolds numbers in the range 1–40, porosity equal to 0.4 and 0.8 and Darcy number Da=5×10-4. In this study, the Darcy–Brinkmann–Forchheimer model is used to model the... 

    Exergoeconomic optimization and sensitivity analysis of a commercial parabolic trough collector for the climate of Tehran, Iran

    , Article Energy Science and Engineering ; Volume 7, Issue 6 , 2019 , Pages 2950-2965 ; 20500505 (ISSN) Hoseinzadeh, H ; Kasaeian, A ; Shafii, M. B ; Sharif University of Technology
    John Wiley and Sons Ltd  2019
    The exergoeconomic analysis is a powerful tool to study an energy system and provide rational decision-making for it. This paper is aimed at exergoeconomic optimization and sensitivity analysis evaluation of the results of a commercial parabolic trough collector (PTC). First, an analysis of optical, thermal, exergy, and economic equations of the PTC system is presented. Then, the objective function and variables are optimized through MATLAB software using the hybrid algorithm code. The objective function as the exergy loss rate is a combination of exergy loss and system cost. The evaluation of the results has been carried out considering the radiation intensity in different months of the... 

    Modeling non-isothermal two-phase fluid flow with phase change in deformable fractured porous media using extended finite element method

    , Article International Journal for Numerical Methods in Engineering ; Volume 122, Issue 16 , April , 2021 , Pages 4378-4426 ; 00295981 (ISSN) Khoei, A. R ; Amini, D ; Mortazavi, M. S ; Sharif University of Technology
    John Wiley and Sons Ltd  2021
    In this article, a computational model is presented for the analysis of coupled thermo-hydro-mechanical process with phase change (evaporation/condensation) in fractured porous media in order to model multiphase fluid flows, heat transfer, and discontinuous deformation by employing the extended finite element method. The ideal gas law and Dalton's law are employed to consider vapor and dry air as miscible gases. To take into account the phase change, latent heat and specific vapor enthalpy are incorporated into the physical model. The set of governing equations consists of linear momentum for the solid-phase, energy balance equation and mass conservation equations of water species (liquid... 

    Herschel-Bulkley rheological parameters of lightweight colloidal gas aphron (CGA) based fluids

    , Article Chemical Engineering Research and Design ; Volume 93 , 2015 , Pages 21-29 ; 02638762 (ISSN) Ziaee, H ; Arabloo, M ; Ghazanfari, M. H ; Rashtchian, D ; Sharif University of Technology
    Institution of Chemical Engineers  2015
    The proper understanding of rheological characteristics of CGA based fluids is of crucial importance in determining the performance of the fluid, in order to maintain the most effective fluid properties for safe, efficient, and economical drilling operation. This paper presents a concise investigation on the effect of concentration of the three main components of a novel environmentally friendly lightweight CGA based drilling fluid, i.e., xanthan gum biopolymer, starch, and biosurfactant, to the Herschel-Bulkley rheological model parameters. The three parameters of Herschel-Bulkley model, i.e., yield stress, fluid consistency, and fluid flow index were calculated by fitting the experimental... 

    Saffman-Taylor instability in yield stress fluids

    , Article Journal of Physics Condensed Matter ; Volume 17, Issue 14 , 2005 , Pages S1209-S1218 ; 09538984 (ISSN) Maleki Jirsaraei, N ; Lindner, A ; Rouhani, S ; Bonn, D ; Sharif University of Technology
    Institute of Physics Publishing  2005
    Pushing a fluid with a less viscous one gives rise to the well known Saffman-Taylor instability. This instability is important in a wide variety of applications involving strongly non-Newtonian fluids that often exhibit a yield stress. Here we investigate the Saffmann-Taylor instability in this type of fluid, in longitudinal flows in Hele-Shaw cells. In particular, we study Darcy's law for yield stress fluids. The dispersion equation for the flow is similar to the equations obtained for ordinary viscous fluids but the viscous terms in the dimensionless numbers conditioning the instability now contain the yield stress. This also has repercussions on the wavelength of the instability as it... 

    Numerical modeling of ureagenesis in a microfluidic channel mimicking a liver lobule

    , Article 2015 22nd Iranian Conference on Biomedical Engineering, ICBME 2015, 25 November 2015 through 28 November 2015 ; 2015 , Pages 54-59 ; 9781467393515 (ISBN) Sharifi, F ; Firoozabadi, B ; Saidi, M. S ; Firoozbakhsh, K ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    Ammonia detoxification is one of the main functions of the liver results in production of urea. In this study ammonia elimination and urea production was simulated in a microchannel mimicking the hepatic porto central axis. Navier- Stockes equations along with convection equations were solved for the related species in the entire domain. Since the Reynolds number was small (~1) the fluid flow regime was laminar. Urea cycle was modeled regarding its four main enzymes. Twelve rate equations were also solved in order to obtain the concentration of each metabolites participating in urea cycle. Concentration of the urea reached its maximum ca. 1.2e-5 M at the end of the channel which is in good... 

    Numerical simulation of a microfluidic system for regular glucose measurement

    , Article 26th National and 4th International Iranian Conference on Biomedical Engineering, ICBME 2019, 27 November 2019 through 28 November 2019 ; 2019 , Pages 60-65 ; 9781728156637 (ISBN) Najmi, A ; Saidi, M. S ; Shahrokhian, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    The aim of this research is to design an implantable integrated microfluidic system in order to regularly measure the glucose level in the human body, nonenzymatically, using the microdialysis method. The main compartments of this system are a micropump, array of hollow microneedles and an electrochemical sensor. At the base of the microneedles, there are located semipermeable membranes, that when the pumped dialysis fluid passes over them, the glucose of the interstitial fluid diffuses into the dialysis fluid and then, in the sensor section, it is measured nonenzymatically using the amperometry method. Both the arrangement of the miconeedles and the amount of the dialysis fluid flow are...