Search for: two-phase-flow
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    Modeling and qualitative experiments on swirling bubbly flows: Single bubble with rossby number of order 1

    , Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 125, Issue 2 , 2003 , Pages 239-246 ; 00982202 (ISSN) Magaud, F ; Najafi, A. F ; Angilella, J. R ; Souhar, M ; Sharif University of Technology
    The behavior of an isolated bubble in a single-phase swirling flow is investigated theoretically and experimentally. The Rossby number is such that the liquid flow can be approximated by a solid-body rotation superposed to a uniform axial velocity. The equations of the motion of the bubble are solved analytically and numerically, by assuming that the bubble is small and does not modify the water flow. Two kinds of bubbles have been considered: clean bubbles and bubbles with a contaminated interface. In the latter case the bubble is treated as a solid sphere. In both cases a critical angular velocity ωc for the rotating device is found. When ω<ωc the trajectory of the bubble is a conical... 

    Numerical Investigation of Two-Phase Flow Contains Water and Oil in Hydrocyclones

    , M.Sc. Thesis Sharif University of Technology Asadi, Mohammad (Author) ; Farhanieh, Bijan (Supervisor)
    Having an efficient and reliable system for oil-water separation is of crucial importance in oil and gas industry. Hydrocyclones have been used for more than a century to separate oil from water as well as sand from liquid or gas. The main objectives of this research are as follows: Determination the hydrocyclone principle of operation, based on computational fluid dynamic simulations. Hydrocyclones, in a spite of simple structure, are widely used in industry such as Petrochemical, Mining, Chemical Industries, Pharmacy, Food and Pulp Industries. The CALC BFC is one phase flow numerical code based on finite volume method and SIMPLEC algorithm. It was extended for simulating the two phase flow... 

    Numerical Simulation of Near-well Flow for Gas-condensate Reservoirs and Investigation of the Effect of Various Flow Parameters

    , M.Sc. Thesis Sharif University of Technology Amirifar, Leyla (Author) ; Taghizade Manzari, Mehrdad (Supervisor)
    This thesis studies a gas condensate reservoir and considers the effect of different parameters. In this group of gas reservoirs, if the pressure drops below the dew point pressure, liquid phase appears. Appearing and disappearing of phases creates four regions in the reservoir. In the region far from the production well, pressure is still above the dew point pressure and vapor phase is present. By approaching production well, pressure drops below the dew point pressure and liquid phase starts to form but it is immobile. In closer regions to the well the liquid phase saturation grows and this phase becomes mobile. As a result, relative permeability of the vapor phase decreases sharply. In... 

    Experimental Study on Two-Phase Flow Characteristics in Micro-Channels

    , M.Sc. Thesis Sharif University of Technology Yavari, Hadi (Author) ; Nouri, Ali (Supervisor)
    The present study provids an experimental investigation on two-pase flow characteristics in microchannels. Experiment were conducted with a mixture of air and water in horizontal circular pyrex channel with 400µm inner diameter. The pressure drop and flow rates of the liquid and gas were measured using new method and images of the flow patterns recorded by high shutter speed camera. The gas and liquid superficial velocity ranges were 0.025-12.5m/s and 0.016-3.6m/s, respectively. The flow pattern map is developed from the observed flow patterns based on phases superficial velocity as wel as We numbers of liquid and gas phases. The flow pattern map is compared with those of larger channels.... 

    Intelligent image-based gas-liquid two-phase flow regime recognition

    , Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 134, Issue 6 , 2012 ; 00982202 (ISSN) Ghanbarzadeh, S ; Hanafizadeh, P ; Hassan Saidi, M ; Sharif University of Technology
    Identification of different flow regimes in industrial systems operating under two-phase flow conditions is necessary in order to safely design and optimize their performance. In the present work, experiments on two-phase flow have been performed in a large scale test facility with the length of 6 m and diameter of 5 cm. Four main flow regimes have been observed in vertical air-water two-phase flow at moderate superficial velocities of gas and water namely: Bubbly, Slug, Churn, and Annular. An image processing technique was used to extract information from each picture. This information includes the number of bubbles or objects, area, perimeter, as well as the height and width of objects... 

    Experimental study and calculation of CO 2-oil relative permeability

    , Article Petroleum and Coal ; Volume 53, Issue 2 , 2011 , Pages 123-131 ; 13377027 (ISSN) Ghoodjani, E ; Bolouri, S. H ; Sharif University of Technology
    Carbon dioxide-oil relative permeability is measured under reservoir condition using core flood apparatus. Then the results are compared with Nitrogen-oil relative permeability. The results show that oil permeability is higher in Carbon dioxide injection compared to nitrogen injection. The comparison of gas permeabilities shows that at the start of injection, nitrogen and carbon dioxide relative permeability are equal, but as the gas saturation increased, Nitrogen relative permeability becomes higher. Finally, a method is proposed to calculate carbon dioxide-oil relative permeability from nitrogen-oil relative permeability. This method can be generalized to calculate relative permeability... 

    Numerical simulation of two-phase flow in airlift pumps using the Physical Influence Scheme

    , Article Progress in Computational Fluid Dynamics ; Volume 10, Issue 3 , 2010 , Pages 186-194 ; 14684349 (ISSN) Hanafizadeh, P ; Saidi, M. H ; Darbandi, M ; Kebriaee, A ; Sharif University of Technology
    A new approach has been presented to solve gas-liquid flow numerically in vertical pipes of air-lift pumps. To improve modelling, a new strategy has been employed with the capability of coupling the continuity and momentum equations and enforcing the role of pressure directly in the continuity equation. This is achieved via applying a novel scheme called the Physical Influence Scheme (PIS). The current finite volume solution is compared with other available numerical solutions. Indeed, they are in fair agreement. However, the present predictions are far superior to those obtained from an existing simple method, which is widely used in airlift pump modelling  

    Experimental and numerical approach to enlargement of performance of primary settling tanks

    , Article Journal of Applied Fluid Mechanics ; Volume 2, Issue 1 , 2009 , Pages 1-12 ; 17353572 (ISSN) Razmi, A ; Firoozabadi, B ; Ahmadi, G ; Sharif University of Technology
    Circulation regions always exist in settling tanks. These regions would result in short-circuiting enlargement of the dead zone and high flow mixing problems and avoid optimal particle sedimentation. Therefore, the main objective of the tank design process is to avoid formation of the circulation zone, which is known as dead zone. Experiments show that the tank performance can be improved by altering the geometry of the tank which leads to a different velocity distributions and flow patterns. In this paper, the presence of a baffle and its effect on the hydrodynamics of the flow field has been investigated in a primary settling tank. Hydrodynamics of the flow field in these basins is... 

    Pore-scale investigation of selective plugging mechanism in immiscible two-phase flow using phase-field method

    , Article Oil and Gas Science and Technology ; Volume 74 , 2019 ; 12944475 (ISSN) Sabooniha, E ; Rokhforouz, M. R ; Ayatollahi, S ; Sharif University of Technology
    Editions Technip  2019
    The selective plugging effect of hydrophobic bacteria cell on secondary oil recovery performance was investigated. Water and aqua solution of purified Acinetobacter strain RAG-1 were injected into an oil-saturated heterogeneous micromodel porous media. Pure water injection expelled oil by 41%, while bacterial solution injection resulted in higher oil recovery efficiency (59%). In the simulation section, a smaller part of the heterogeneous geometry was applied as a computational domain. A numerical model was developed using coupled Cahn-Hilliard phase-field method and Navier-Stokes equations, solved by a finite element solver. In the non-plugging model, approximately 50% of the matrix oil was... 

    Innovations in non-linear oscillations of a pendent drop from a capillary tip during formation and detachment - an LBM simulation

    , Article Journal of Applied Fluid Mechanics ; Volume 14, Issue 1 , 2020 , Pages 331-344 Ghorbanifar, S ; Taeibi Rahni, M ; Zareh, M ; Sharif University of Technology
    Isfahan University of Technology  2020
    Individual drops are suitable tools to study the liquid-fluid interfacial properties. In this work, force-displacement equation and non-linear oscillations of a pendent drop are numerically investigated. The presented novel force-displacement function allows following the dynamics of a pendent drop and realizing its elastic behavior. The growth and detachment of drop, which is pending due to gravity from a capillary tip, is considered (assuming high density and high viscosity ratios and immiscible two-phase flows). Two-dimensional multi-relaxation time lattice Boltzmann method (MRT-LBM) was used to simulate growth, detachment, and oscillations of the drop using a conservative model for... 

    Effects of non-dimensional parameters on formation and break up of cylindrical droplets

    , Article 2004 ASME Heat Transfer/Fluids Engineering Summer Conference, HT/FED 2004, Charlotte, NC, 11 July 2004 through 15 July 2004 ; Volume 2 B , 2004 , Pages 1339-1342 Taeibi Rahni, M ; Sharafatmand, S ; Sharif University of Technology
    American Society of Mechanical Engineers  2004
    The consistent behavior of non-dimensional parameters on the formation and break up of large cylindrical droplets has been studied by direct numerical simulations (DNS). A one-fluid model with a finite difference method and an advanced front tracking scheme was employed to solve unsteady, incompressible, viscous, immiscible, multi-fluid, twodimensional Navier-Stokes equations. This time dependent study allows investigation of evolution of the droplets in different cases. For moderate values of Atwood number (AT), increasing Eotvos number (Eo) explicitly increases the deformation rate in both phenomena. Otherwise, raising the Ohnesorge number (Oh) basically amplifies the viscous effects.... 

    Numerical modelling of two-phase flow in a geocentrifuge

    , Article Environmental Modelling and Software ; Volume 18, Issue 3 , 2003 , Pages 231-241 ; 13648152 (ISSN) Ataie Ashtiani, B ; Hassanizadeh, S. M ; Oung, O ; Weststrate, F. A ; Bezuijen, A ; Sharif University of Technology
    Elsevier BV  2003
    In this paper, results of DNAPL spreading experiments carried out in a geocentrifuge are analysed. The experiments are performed in the GeoDelft geocentrifuge. The experiments investigate the intrusion of a known amount of PCE into a water-saturated soil sample. They are carried out under 12, 15, and 30g conditions. The objectives of these experiments were to assess the potential of geocentrifuge tests for the study of environmental problems, to investigate the effect of acceleration on the spreading of DNAPL, and to determine whether capillary pressure-saturation (Pc-S) curves of soils measured in a geocentrifuge are applicable under 1g conditions. In the present paper, numerical simulation... 

    Effects of heterogeneities on capillary pressure-saturation-relative permeability relationships

    , Article Journal of Contaminant Hydrology ; Volume 56, Issue 3-4 , 2002 , Pages 175-192 ; 01697722 (ISSN) Ataie Ashtiani, B ; Majid Hassanizadeh, S ; Celia, M. A ; Sharif University of Technology
    In theories of multiphase flow through porous media, capillary pressure-saturation and relative permeability-saturation curves are assumed to be intrinsic properties of the medium. Moreover, relative permeability is assumed to be a scalar property. However, numerous theoretical and experimental works have shown that these basic assumptions may not be valid. For example, relative permeability is known to be affected by the flow velocity (or pressure gradient) at which the measurements are carried out. In this article, it is suggested that the nonuniqueness of capillary pressure-relative permeability-saturation relationships is due to the presence of microheterogeneities within a laboratory... 

    Effective parameters for two-phase flow in a porous medium with periodic heterogeneities

    , Article Journal of Contaminant Hydrology ; Volume 49, Issue 1-2 , 2001 , Pages 87-109 ; 01697722 (ISSN) Ataie Ashtiani, B ; Hassanizadeh, S. M ; Oostrom, M ; Celia, M. A ; White, M. D ; Sharif University of Technology
    Computational simulations of two-phase flow in porous media are used to investigate the feasibility of replacing a porous medium containing heterogeneities with an equivalent homogeneous medium. Simulations are performed for the case of infiltration of a dense nonaqueous phase liquid (DNAPL) in a water-saturated, heterogeneous porous medium. For two specific porous media, with periodic and rather simple heterogeneity patterns, the existence of a representative elementary volume (REV) is studied. Upscaled intrinsic permeabilities and upscaled nonlinear constitutive relationships for two-phase flow systems are numerically calculated and the effects of heterogeneities are evaluated. Upscaled... 

    Two-phase flow in microchannels with a bounding porous medium

    , 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 263-268 ; 9780791844632 (ISBN) Nouri Borujerdi, A ; Sharif University of Technology
    This paper investigates numerical simulation of one-dimensional homogeneous adiabatic gas-liquid two-phase flow in a rectangular microchannel with one boundary porous wall under the assumption of hydrophobic condition. Gas enters the microchannel with a uniform velocity and liquid is injected through the porous side wall. The present approach is to simulate water injection effects and developing mechanism of two-phase flow. The modeling and solution of the conservation equations provide pressure drop, vapor quality, void fraction and tow-phase mixture velocity for different water injection rates. The results show that velocity and pressure drop significantly perturbed when the water... 

    Study of heterogeneity loss in upscaling of geological maps by introducing a cluster-based heterogeneity number

    , Article Physica A: Statistical Mechanics and its Applications ; Volume 436 , October , 2015 , Pages 1-13 ; 03784371 (ISSN) Ganjeh Ghazvini, M ; Masihi, M ; Baghalha, M ; Sharif University of Technology
    Elsevier  2015
    The prediction of flow behavior in porous media can provide useful insights into the mechanisms involved in CO2 sequestration, petroleum engineering and hydrology. The multi-phase flow is usually simulated by solving the governing equations over an efficient model. The geostatistical (or fine grid) models are rarely used for simulation purposes because they have too many cells. A common approach is to coarsen a fine gird realization by an upscaling method. Although upscaling can speed up the flow simulation, it neglects the fine scale heterogeneity. The heterogeneity loss reduces the accuracy of simulation results. In this paper, the relation between heterogeneity loss during upscaling and... 

    Study of behavior of two phase flow in vertical large diameter pipe

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 12 November 2010 through 18 November 2010 ; Volume 7, Issue PARTS A AND B , November , 2010 , Pages 1735-1741 ; 9780791844441 (ISBN) Kebriayi, M. H ; Karrabi, H ; Rezasoltani, M ; Saidi, M. H ; Sharif University of Technology
    Knowledge of Air-water two phase flows is significant to different engineering systems such as chemical reactors and power plant and petrochemical and petroleum industry. One of the most industrial cases of two phase flow is two phase flow in vertical large pipes. In this paper in order to find two phase flow behavior along vertical large diameter pipes we simulate air inlets with different number of holes and different hole diameters in the same flow rate of air. In addition, flow characteristics such as cross-sectional void fraction and velocity and pressure were considered. To achieve this aim, main equations of flow have been developed for investigation of flow behavior in air-water two... 

    Improvement of airlift pump performance based on the exergy analysis

    , Article Proceedings of the 23rd International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems, ECOS 2010, 14 June 2010 through 17 June 2010, Lausanne ; Volume 1 , 2010 , Pages 489-497 ; 9781456303006 (ISBN) Ghanbarzadeh, S ; Hanafizadeh, P ; Gholampour, P ; Shams, H ; Saidi, M. H ; Sharif University of Technology
    Aabo Akademi University  2010
    Airlift systems (ALS) are widely used in various fields such as petroleum and oil extracting industries. As gas-liquid two phase flow is the main part of the flow through these systems, the analysis of such systems accompanies with problems of two phase flow modeling. However, exergy analysis could be a simple method for modeling of airlift systems. In the present study, an analytical model based on thermodynamic principles has been implemented on each phase to analyze the performance of airlift systems. The experimental data were collected at a large scale multiphase flow test rig for the airlift pump with 6m height and diameter of 50 mm. Finally, irreversibility terms, energy destruction,... 

    A finite-volume ELLAM for non-linear flux convection-diffusion problems

    , Article International Journal of Non-Linear Mechanics ; Volume 44, Issue 2 , 2009 , Pages 129-136 ; 00207462 (ISSN) Fatehi, R ; Taghizadeh Manzari, M ; Kazemzadeh Hannani, S ; Sharif University of Technology
    In this paper, a modified finite-volume Eulerian-Lagrangian localized adjoint method (FVELLAM) extended for convection-diffusion problems with a non-linear flux function is introduced. Tracking schemes are discussed using viscous Burgers' equation. It is shown that in order to have smooth results, only the new time level values should be used in tracking process. Then, the proposed method is employed to study immiscible incompressible two-phase flows in porous media. Various one- and two-dimensional test cases involving internal sources and sinks are solved and accuracy of solution and performance of the method are investigated by comparing the results obtained using FVELLAM with those of... 

    The role of surface wettability on the heat transfer in liquid-liquid two-phase flow in a microtube

    , Article Physics of Fluids ; Volume 31, Issue 8 , 2019 ; 10706631 (ISSN) Moezzi, M ; Kazemzadeh Hannani, S ; Farhanieh, B ; Sharif University of Technology
    American Institute of Physics Inc  2019
    Liquid-liquid two-phase flow is capable of boosting heat transfer in microdevices compared to the single-phase and gas-liquid flows. A thorough investigation is performed here to characterize the heat transfer in water-oil flow in a microtube. Finite element method along with the level-set model is employed for numerical simulation. A main part of this paper is devoted to studying the effect of wettability on the heat transfer performance. Four contact angles of 0°, 30°, 150°, and 180° are investigated, which revealed that the contact angle of 150° produces the highest Nusselt number (Nu). Triple points form at this contact angle, and the slugs slide on the wall, which results in more...