Search for: flow-of-fluids
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    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 Darbandi, M ; Banaeizadeh, A ; Schneider, G. E ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc  2005
    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... 

    Lattice Boltzmann method on quadtree grids for simulating fluid flow through porous media: A new automatic algorithm

    , Article Physica A: Statistical Mechanics and its Applications ; Vol. 392, issue. 20 , May , 2013 , p. 4772-4786 ; ISSN: 03784371 Foroughi, S ; Jamshidi, S ; Masihi, M ; Sharif University of Technology
    During the past two decades, the lattice Boltzmann (LB) method has been introduced as a class of computational fluid dynamic methods for fluid flow simulations. In this method, instead of solving the Navier Stocks equation, the Boltzmann equation is solved to simulate the flow of a fluid. This method was originally developed based on uniform grids. However, in order to model complex geometries such as porous media, it can be very slow in comparison with other techniques such as finite differences and finite elements. To eliminate this limitation, a number of studies have aimed to formulate the lattice Boltzmann on the unstructured grids. This paper deals with simulating fluid flow through a... 

    Rock Type Connectivity Estimation Using Percolation Theory

    , Article Mathematical Geosciences ; Vol. 45, issue. 3 , April , 2013 , p. 321-340 ; ISSN: 18748961 Sadeghnejad, S ; Masihi, M ; Pishvaie, M ; King, P. R ; Sharif University of Technology
    Complicated sedimentary processes control the spatial distribution of geological heterogeneities. This serves to make the nature of the fluid flow in the hydrocarbon reservoirs immensely complex. Proper modeling of these heterogeneities and evaluation of their connectivity are crucial and affects all aspects of fluid flow. Since the natural variability of heterogeneity occurs in a myriad of length scales, accurate modeling of the rock type connectivity requires a very fine scheme, which is computationally very expensive. Hence, this makes other alternative methods such as the percolation approach attractive and necessary. The percolation approach considers the hypothesis that a reservoir can... 

    Theoretical and experimental investigation of density jump on an inclined surface

    , Article Scientia Iranica ; Vol. 21, Issue. 5 , 2014 , pp. 1655-1665 ; ISSN :1026-3098 Najafpour, N ; Sarnie, M ; Firoozabadi, B ; Afshin, H ; Sharif University of Technology
    The density jump on an inclined surface is analyzed using an integral method by applying mass and momentum conservation equations. The jump occurs in a two-layered fluid flow in which the upper layer is stagnant and very deep. A relation is derived, which gives the conjugate depth ratio as a function of inlet densimetric Froude number, inlet concentration ratio, bed slope and entrainment. A set of experiments are performed to verify the relation. The theory and the measurements are in good agreement. The analysis reveals that increasing the surface inclination results in a decrease in the conjugate depth ratio. This analysis also shows that the densimetric Froude number just after the jump... 

    Size-dependent characteristics of electrostatically actuated fluid-conveying carbon nanotubes based on modified couple stress theory

    , Article Beilstein Journal of Nanotechnology ; Volume 4, Issue 1 , 2013 , Pages 771-780 ; 21904286 (ISSN) Fakhrabadi, M. M. S ; Rastgoo, A ; Ahmadian, M. T ; Sharif University of Technology
    The paper presents the effects of fluid flow on the static and dynamic properties of carbon nanotubes that convey a viscous fluid. The mathematical model is based on the modified couple stress theory. The effects of various fluid parameters and boundary conditions on the pull-in voltages are investigated in detail. The applicability of the proposed system as nanovalves or nanosensors in nanoscale fluidic systems is elaborated. The results confirm that the nanoscale system studied in this paper can be properly applied for these purposes  

    The study of microfilter performance in different environments using DSMC

    , Article ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2011, 19 June 2011 through 22 June 2011 ; Volume 1 , June , 2011 , Pages 289-294 ; 9780791844632 (ISBN) Darbandi, M ; Karchani, A ; Khaledi Alidusti, R ; Schneider, G. E ; Sharif University of Technology
    Microfilters are commonly used to block undesirable particles in the fluid flows and to control the flow patterns in MEMS. The main purpose of this study is to understand the effect of gas type on density, pressure, Mach number, and velocity distributions of fluid flows through a microfilter. The Knudsen number is the slip flow regime passing through the microfilter. We use direct simulation Monte Carlo (DSMC) method to simulate the flow of nitrogen, helium, oxygen, air and methane passing through a specific microfilter. The geometry of microfilter is unique in all cases. Our results confirm that every gas performs a different performance passing through a specific microfilter, and that the... 

    Application of electrostatically actuated carbon nanotubes in nanofluidic and bio-nanofluidic sensors and actuators

    , Article Measurement: Journal of the International Measurement Confederation ; Volume 73 , September , 2015 , Pages 127-136 ; 02632241 (ISSN) Seyyed Fakhrabadi, M. M ; Rastgoo, A ; Ahmadian, M. T ; Sharif University of Technology
    Elsevier  2015
    The paper investigates the effects of fluid flow on the static and dynamic behaviors of electrostatically actuated carbon nanotubes using nonlocal elasticity theory. The influences of various parameters of fluid flow including fluid viscosity, velocity, mass and temperature on the mechanical behaviors of the carbon nanotubes under static and step DC voltages are studied using this theory. The results computed from the nonlocal elasticity theory are compared with those estimated using the classical elasticity theorem and the outcomes demonstrate the applicability of the electrostatically actuated carbon nanotubes as nano sensors and nano actuators in nanofluidic systems. The nanosystem can be... 

    Induced soap-film flow by non-uniform alternating electric field

    , Article Journal of Electrostatics ; Volume 73 , February , 2015 , Pages 112-116 ; 03043886 (ISSN) Shirsavar, R ; Ramos, A ; Amjadi, A ; Taherinia, J ; Mashhadi, M ; Nejati, A ; Sharif University of Technology
    Elsevier  2015
    Fluid flows generated on soap films by non-uniform alternating electric fields are studied. Two parallel metal rods subjected to an AC voltage are placed perpendicular to the soap film, which is anchored in a dielectric frame. The fluid flow is generated by electrohydrodynamic induction. At very low signal frequencies there is induced surface charge, but there is no tangential electric field at the surface, so there is no force and no flow. Fluid flow is observed increasing the frequency, when there are both surface charge and tangential electric field. The flow velocity increases with decreasing thickness of the soap film  

    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... 

    Challenges of fluid phase behavior modeling in Iranian retrograde gas condensate reservoirs

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 37, Issue 6 , Feb , 2015 , Pages 663-669 ; 15567036 (ISSN) Nasriani, H. R ; Asadi, E ; Nasiri, M ; Khajenoori, L ; Masihi, M ; Sharif University of Technology
    Taylor and Francis Inc  2015
    Production from gas condensate reservoirs requires precise determination of reservoir fluid properties along with their positive impact on real reservoir performance evaluation and fluid in place volume calculation. This fact is particularly important because liquid drop out phenomena occurs as a result of pressure drop due to fluid production and condensate remains in reservoir [Mohebzadeh, 2005. In this study the challenges and problems of fluid phase behavior simulation in southern Iranian retrograde gas condensate reservoirs is discussed. Most of the problems and challenges are inaccuracy of equation of states near the critical point, special conditions and produced fluid flow... 

    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... 

    Simulation of polymer chain driven by DPD solvent particles in nanoscale flows

    , Article ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels Collocated with 3rd Joint US-European Fluids Engineering Summer Meeting, ICNMM2010, 1 August 2010 through 5 August 2010, Montreal, QC ; Issue PARTS A AND B , 2010 , Pages 1035-1040 ; 9780791854501 (ISBN) Darbandi, M ; Zakeri, R ; Schneider, G. E ; Sharif University of Technology
    In this study, we simulate the motion and reformation of polymer chain in the nanoscale fluid flow motion of the DPD (Dissipative Particle Dynamics) solvent. The behavior of polymer chain through DPD solvent is studied for 2D and 3D considerations. We implement two body forces of Poiseuille flow and electroosmotic flow to the DPD fluid particles. In case of the electroosmotic flow force, we show that the movement of polymer chain via the electroosmotic phenomenon provides less dispersion than that of the Poiseuille flow for the same polymer chain movement  

    An extended finite element method for hydraulic fracture propagation in deformable porous media with the cohesive crack model

    , Article Finite Elements in Analysis and Design ; Volume 73 , 2013 , Pages 77-95 ; 0168874X (ISSN) Mohammadnejad, T ; Khoei, A. R ; Sharif University of Technology
    In this paper, a fully coupled numerical model is developed for the modeling of the hydraulic fracture propagation in porous media using the extended finite element method in conjunction with the cohesive crack model. The governing equations, which account for the coupling between various physical phenomena, are derived within the framework of the generalized Biot theory. The fluid flow within the fracture is modeled using the Darcy law, in which the fracture permeability is assumed according to the well-known cubic law. By taking the advantage of the cohesive crack model, the nonlinear fracture processes developing along the fracture process zone are simulated. The spatial discretization... 

    Identification of flow units using methods of testerman statistical zonation, flow zone index, and cluster analysis in tabnaak gas field

    , Article Journal of Petroleum Exploration and Production Technology ; Volume 6, Issue 4 , 2016 , Pages 577-592 ; 21900558 (ISSN) Mahjour, S. K ; Ghasem Al Askari, M. K ; Masihi, M ; Sharif University of Technology
    Springer Verlag 
    The relation between porosity and permeability parameters in carbonated rocks is complicated and indistinct. Flow units are defined with aim of better understanding reservoir unit flow behavior and relation between porosity and permeability. Flow units reflect a group of rocks with same geological and physical properties which affect fluid flow, but they do not necessarily coincide with boundary of facies. In each flow unit homogeneity of data is preserved and this homogeneity fades in the boundaries. Here, in this study, three methods are used for identification of flow units and estimation of average porosity and permeability in three wells of Tabnaak gas field located in south of Iran.... 

    Numerical study of external flow over ducts with various cross-sections

    , Article Defect and Diffusion Forum ; Volume 366 , 2016 , Pages 10-16 ; 10120386 (ISSN) Maleki, E ; Sadrhosseini, H ; Sharif University of Technology
    Trans Tech Publications Ltd 
    In this article a comprehensive numerical study is performed to compare the effect of fluid flow across a duct with various cross sectional shapes and with different velocities of the flow. Circular, elliptical and rectangular cross sections have been chosen for the ducts and air flows across them with four values of low Reynolds numbers in the range of Re = 1 to Re = 1000. Continuity and momentum equations with proper boundary conditions are solved in two dimensions. Streamlines, pressure distribution and Velocity profiles are obtained and creation of vortices, boundary layers, separation region, wake region, reattachment point and stagnation points are studied in detail and the results are... 

    Blockage-ratio effect on aerosol behavior of soot nano-pm in a combustor burning jet propulsion fuel

    , Article 46th AIAA Thermophysics Conference, 2016, 13 June 2016 through 17 June 2016 ; 2016 ; 9781624104350 (ISBN) Darbandi, M ; Ghafourizadeh, M ; Schneider, G. E ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc, AIAA  2016
    In this study, we numerically investigate the size effect of a bluff body, embedded inside a combustor, on the formation of carbonaceous nano-particulate matter (PM). The combustor is fed with a jet propulsion fuel. We first evaluate our extended numerical tool by simulating a turbulent kerosene/air nonpremixed flame in a combustor. The achieved results are then compared with those of experiment. The comparisons show that there are good agreements between them. Next, we embed an O-ring type flame holder inside the combustor to change its configuration, i.e., to extend it to a bluff-body burner. Assuming a constant air mass flow rate, we investigate the blockage ratio effects of the burner... 

    Recovery of drop in heat transfer rate for a rotating system by nanofluids

    , Article Journal of Molecular Liquids ; Volume 220 , 2016 , Pages 961-969 ; 01677322 (ISSN) Zeibi Shirejini, S. R ; Rashidi, S ; Abolfazli Esfahani, J ; Sharif University of Technology
    This paper simulates Al2O3-water nanofluid flow and forced convection around a rotating circular cylinder. The governing parameters are Reynolds number (1 ≤ Re ≤ 100), solid volume fraction of nanoparticles (0 ≤ φ ≤ 0.05) and non-dimensional rotation rate (0 ≤ α ≤ 3). The simulations are performed to study the effects of mentioned parameters on the heat transfer rate and fluid flow characteristics. The governing equations including the continuity, momentum, and energy equations are solved with a finite volume method. It is observed that the reduction of heat transfer with increase in rotation rate is in the vicinity of 6.9% and 32% for Re = 5 and 100, respectively at φ = 0.05. Furthermore,... 

    Numerical simulation of heat transfer in mixed electroosmotic pressure-driven flow in straight microchannels

    , Article Journal of Thermal Science and Engineering Applications ; Volume 8, Issue 2 , 2016 ; 19485085 (ISSN) Shamloo, A ; Merdasi, A ; Vatankhah, P ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2016
    This paper investigates two-dimensional, time-independent elecroosmotic pressuredriven flow generated by a direct current electric potential with asymmetrical and symmetrical zeta potential distributions along the microchannel walls. Fluid flow through the horizontal microchannel is simulated using a numerical method. Two different cases are proposed to study the effect of electric potential on the flow field. First, negative electric potential is applied on the microchannel walls. In this case, large segments with negative electric potential are initially placed on the first half of the microchannel walls with two different arrangements. Afterward, smaller segments with negative electric... 

    Filtration of aerosol particles by cylindrical fibers within a parallel and staggered array

    , Article Microsystem Technologies ; Volume 22, Issue 5 , 2016 , Pages 965-977 ; 09467076 (ISSN) Banihashemi Tehrani, S. M ; Moosavi, A ; Sadrhosseini, H ; Sharif University of Technology
    Springer Verlag  2016
    The World Health Organization (WHO) in 2013 reported that more than seven million unexpected losses every year are credited to air contamination. Because of incredible adaptability and expense viability of fibrous filters, they are broadly used for removing particulates from gasses. The influence of appropriate parameters, e.g., the fiber arrangement, solid volume fraction (SVF or α), fluid flow face velocity (mean inlet velocity), and filter thickness (Ix), on pressure drop and deposition efficiency are researched. Furthermore, to study the effects of variation of the laminar flow regime and fiber’s cross-sectional shape on the deposition of particles, only a single square fiber has been... 

    Numerical optimization and inverse study of a microfluidic device for blood plasma separation

    , Article European Journal of Mechanics, B/Fluids ; Volume 57 , 2016 , Pages 31-39 ; 09977546 (ISSN) Shamloo, A ; Vatankhah, P ; Bijarchi, M. A ; Sharif University of Technology
    Elsevier Ltd  2016
    In this paper, a passive microfluidic device for continuous real time blood plasma separation has been studied and optimized. A numerical model is used to solve both the fluid flow and the particles confined within it. Red blood cells are considered as particles with diameter of 7μm. A parametric study is performed in order to characterize the effect of different parameters on separation and purity efficiency. In this study, four different variables were introduced to design the microfluidic device for blood plasma separation including: the angle between the daughter channels and the main channel, the widths, the diffuse angle and the number of daughter channels. Results show that the...