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    Non-equilibrium model of three-phase flow in porous media in presence of capillary and gravity forces

    , Article Journal of Hydrology ; Vol. 478, issue , November , 2013 , p. 119-131 ; ISSN: 00221694 Jahanbakhshi, S ; Ghazanfari, M. H ; Masihi, M ; Sharif University of Technology
    In this work a generalized non-equilibrium model of three-phase flow in porous media including gravity as well as capillary terms is developed and used for analysis of Riemann's problem in several three-phase systems. The proposed model uses the extension of Barenblatt model to three-phase systems considering dynamic effects in both relative permeability and capillary pressure functions. We compare the solution of the Riemann's problem when non-equilibrium effects are included. While equilibrium formulation develops unstable oscillatory solution in the elliptic region, non-equilibrium solution is smooth and stable. The results of this work might be helpful to better understanding the... 

    Investigating the role of ultrasonic wave on two-phase relative permeability in a free gravity drainage process

    , Article Scientia Iranica ; Vol. 21, issue. 3 , 2014 , p. 763-771 Keshavarzi, B ; Karimi, R ; Najafi, I ; Ghazanfari, M. H ; Ghotbi, C ; Sharif University of Technology
    In this work, the process of free gravity drainage under the influence of ultrasonic waves was investigated. A glass bead pack porous medium was used to perform free fall gravity drainage experiments. The tests were performed in the presence and absence of ultrasonic waves, and the data of recovery were recorded versus time under both conditions. The wetting phase relative permeability curves were obtained using the data of recovery versus time, based on the Hagoort backward methodology. Subsequently, using the wetting phase relative permeability curve, the relative permeability of non-wetting phases were calculated by performing history matching to the experimental production data. The... 

    Estimation of naturally fractured oil reservoir properties using the material balance method

    , Article Scientia Iranica ; Volume 21, Issue 3 , 2014 , Pages 781-791 ; ISSN: 10263098 Ebrahimi, N ; Jamshidi, S ; Gholinezhad, S ; Sharif University of Technology
    In fractured reservoirs, a large variation of permeability due to the presence of fractures leads to changes in the production mechanism compared to conventional reservoirs. Hence, an appropriate model with the ability to describe the reservoir properly can provide a more confident prediction of its future performance. One of the features of a representative model is the number and height of the matrix blocks. The determination of these two parameters is one of the decisive steps in the calculation of an accurate amount of oil production from these reservoirs. In fact, matrix height shows its effect as a gravity force, which is one of the driving mechanisms. If the matrix height is less than... 

    Densification behavior and mechanical properties of biomimetic apatite nanocrystals

    , Article Current Nanoscience ; Volume 7, Issue 5 , 2011 , Pages 776-780 ; 15734137 (ISSN) Eskandari, A ; Aminzare, M ; Hassani, H ; Barounian, H ; Hesaraki, S ; Sadrnezhaad, S. K ; Sharif University of Technology
    Nanocrystalline hydroxyapatite (nHA) of 50 nm average diameter and length to diameter ratio of >3 was synthesized by biomimetic method. Non-isothermal sintering improved densification behavior and mechanical properties of apatite to 0.88 maximum fractional density, 70MPa bending strength, 148MPa compressive strength and 2.53GPa microhardness at sintering temperature of 1250°C. Higher sintering temperatures resulted in the decomposition of the apatite and in-situ biphasic calcium phosphate HAP/TCP formation. This process lowered apatite densification and weakened mechanical properties of the sintered specimen. Transmission electron microscopy (TEM), x-ray diffraction (XRD) and field emission... 

    Computational simulation of marangoni convection under microgravity condition

    , Article Scientia Iranica ; Volume 16, Issue 6 B , 2009 , Pages 513-524 ; 10263098 (ISSN) Saidi, M. H ; Taeibi Rahni, M ; Asadi, B ; Ahmadi, G ; Sharif University of Technology
    In this work, the rising of a single bubble in a quiescent liquid under microgravity condition was simulated. In addition to general studies of microgravity effects, the initiation of hydrodynamic convection, solely due to the variations of interface curvature (surface tension force) and thus the generation of shearing forces at the interfaces, was also studied. Then, the variation of surface tension due to the temperature gradient (Marangoni convection), which can initiate the onset of convection even in the absence of buoyancy, was studied. The related unsteady incompressible full Navier-Stokes equations were solved using a finite difference method with a structured staggered grid. The... 

    An Analytic Solution for the Frontal Flow Period in 1D Counter-Current Spontaneous Imbibition into Fractured Porous Media Including Gravity and Wettability Effects

    , Article Transport in Porous Media ; Volume 89, Issue 1 , 2011 , Pages 49-62 ; 01693913 (ISSN) Mirzaei Paiaman, A ; Masihi, M ; Standnes, D. C ; Sharif University of Technology
    Including gravity and wettability effects, a full analytical solution for the frontal flow period for 1D counter-current spontaneous imbibition of a wetting phase into a porous medium saturated initially with non-wetting phase at initial wetting phase saturation is presented. The analytical solution applicable for liquid-liquid and liquid-gas systems is essentially valid for the cases when the gravity forces are relatively large and before the wetting phase front hits the no-flow boundary in the capillary-dominated regime. The new analytical solution free of any arbitrary parameters can also be utilized for predicting non-wetting phase recovery by spontaneous imbibition. In addition, a new...