Multiphase Flow

The theory-based closure relations for the wall and interfacial shear stresses obtained previously for laminar stratified flow, are extended to be applicable also to turbulent flows in either or both of the phases. The closure relations are formulated in terms of the single-phase-based expressions, which are augmented by two-phase interaction factors, due to the flow of the two phases in the same channel. These closure relations, which are valid for smooth stratified flow in horizontal or inclined pipes, were used as a platform for introducing necessary empirical corrections required in the stratified wavy flow regime. Based on experimental data available from the literature, new empirical correlations for the wave effect on the interface curvature, on the interfacial shear and on the liquid wall shear were obtained. The predictions of the two-fluid model for the pressure gradient and holdup are tested against extensive data bank and some analytical solutions for stratified flows. T...

The enormous cost of handling the challenges of flow assurance in subsea wells, flowlines, and risers, especially in deepwater applications, has necessitated a proactive approach to prevent their risk of occurrence. To ensure that transportation of the hydrocarbon is economical and efficient from the subsea wellhead to the processing units, a flow assurance heat management system is relevant in the design and planning of a fluid transport system. Consequently, the advancement of new technologies to serve the increasing need by exploring the technologically challenging and hostile subsea fields is of great importance. A comparative study on heat management systems in flowlines was conducted from the top five publishers (Elsevier, Springer, Taylor & Francis, Wiley, and Sage) based on the number of publications to determine the level of work done by researchers in the last decade, the figures from the study showed the need for scientific research in the field of active heating. Additionally, a review was implemented to ascertain the likely advantages and drawbacks of each technique, its limitations concerning field applications and then recommend suitable cost-effective technique(s). The active heating system gives the most cost-effective solution for subsea deepwater fields.

Transport of emulsions in porous media is relevant to several subsurface applications. Many enhanced oil recovery (EOR) processes lead to emulsion formation and as a result conformance originating in the flow of a dispersed phase may arise. In some EOR processes, emulsion is injected directly as a mobility control agent. Modeling the flow of emulsion in porous media is extremely challenging due to the complex nature of the associated flows and numerous interfaces. The descriptions based on effective viscosity are not valid when the drop size is of the same order of magnitude as the pore-throat characteristic length scale. An accurate model of emulsion flow through porous media should describe this local change in mobility. The available filtration models do not take into account the variation of the straining and capturing rates with the local capillary number. In this work, we present experiments of emulsion flow through sandstone cores of different permeability and a first step on a capillary network model that uses experimentally determined pore-level constitutive relationships between flow rate and pressure drop in constricted capillaries to obtain representative macroscopic flow behavior emerging from microscopic emulsion flow at the pore level. A parametric analysis is conducted to study the effect of the permeability and dispersed phase droplet size on the flow response to emulsion flooding in porous media. The network model predictions qualitatively describe the oil-water emulsion flow behavior observed in the experiments.

... Moussa et al. [15] investigated potential benefits of sound in speeding up fluidized bed combustion. ... Z Chem. Eng, 65 (1987) 536. [4] S. Mori, A. Yamamoto, S. lwata, T. Haruta, I. Yamada and E. Mizutani, AIChE Syrup. Ser., 86 (276) (1990) 88. ...

Mixed flows characterized by a simultaneous occurrence of free surface and pressurized flows are often encountered in hydraulic engineering. Numerous researches have been dedicated to unify the mathematical description of both flows. Herein, shock-capturing models succeed in giving a unique set of equations. However, no method accounts for both air-entrapment and air-entrainment. This study proposes an original model to simulate air–water interactions in mixed flows. The new approach relies on the area-integration of a three-phase model over two layers. The applicability of this free surface model is extended to pressurized flows by a modified pressure term accounting for the dispersed air. The derived modelling system WOLF IMPack is then validated. The code successfully simulates open channel flows, mixed flows and water hammer in a unified framework, including air–water interactions, in structures like the drainage network.

Boiling heat transfer experiments were performed in a small circular channel (d = 2.46) and a small rectangular channel (dh = 2.40 mm) with Refrigerant 12. The channel sizes are representative of flow passages in compact evaporators. An experimental technique minimized test section end effects which can be appreciable relative to the heat transfer in these small channels. Local heat transfer results were obtained over a range of qualities up to 0.94, a mass flux range of 44–832 kg/m's, and a heat flux range of 3.6–129 kW/m2. Saturation pressure was nearly constant, averaging 0.82 MPa for most of the testing, with some tests performed at a lower pressure of 0.51 MPa. Local heat transfer coefficients were determined experimentally as a function of quality along the length of the test section. Heat transfer rates were compared with results of previous experiments in which Refrigerant 113 in a 2.92-mm diameter small circular tube was used. The effects of channel geometry and fluid properties on heat transfer, as well as insights relative to heat transfer mechanisms in small channels, are presented. Results are presented for both nucleation- (wall superheat above 2.75°C) and convection-dominant boiling heat transfer regimes and compared with large-channel predictions. The heat transfer data for the two fluids were successfully correlated in the nucleation-dominant region.

Abstract Fluid flow phenomena in a cylindrical bath stirred by a top submerged lance (TSL) gas injection was investigated by using the computational fluid dynamic (CFD) modeling technique for an isothermal air–water system. The multiphase flow simulation, based on ...

A scaling analysis based on the field equations for two phases and the jump conditions at the interface is carried out to deduce a balance of forces acting on a Taylor drop rising through stagnant liquid in a vertical pipe. The force balance is utilized to deduce a functional form of an empirical correlation of terminal velocity of the Taylor

The unsteady flow can be analysed by Saint-Venant equations. These equations can be solved by characteristics and finite difference methods. The Saint-Venant equations are changed into four complete differential equations in characteristics method and these equations are solved by drawing two characteristics lines. The Saint-Venant equations are changed into set nonlinear equations and are solved using Preissman scheme in finite difference method. This set of equation is changed into linear equation using Newton-Rafson method and can be solved using Sparce method. In this research, the results of the two method were compared and this was shown that: 1) these two methods can draw the surface profiles and flow hydrograph as well; 2) the finite difference method is more accurate than that one; 3) the mesh size in finite difference method can be larger than that one; 4) the difference between two methods are increased by increasing the time and distance.. He is interested in the topics of: groundwater hydrology, irrigation and drainage engineering, sustainable development and environmental assessment, climate and integrated and sustainable water resource management, artificial neural network, and genetic algorithm. He has contributed to more than 80 publications in journals, books, or as technical reports. Currently, he is as a

ABSTRACT A conservative local interface sharpening scheme has been developed for the constrained interpolation profile method with the conservative semi-Lagrangian scheme (CIP-CSL), since CIP-CSL does not feature a mechanism to control the interface thickness, thus causing an increase of numerical error with the advance of the time step. The proposed sharpening scheme is based on the conservative level set method proposed by Olsson and Kreiss. However, since the Olsson’s method can cause excessive deformation of the free-surface in certain circumstances, we propose an improvement of the method by developing the local sharpening technique. Several advection tests are presented to assess the correctness of the advection and the improved interface sharpening scheme. This is followed by the validations of dam-breaking flow and the rising bubble flows. The mass of the fluid is exactly conserved and the computed terminal velocity of the rising bubble agree well with the experiments compared to other numerical methods such as VOF, the front tracking method, and the level set method.

Models published in the two-phase flow literature for the added mass coefficient of a dilute bubbly dispersion are discussed and compared. It is shown that the differences between the models are mainly due to the different ways in which the added mass is defined. Also, approximate expressions for the added mass coefficient of non-dilute bubbly dispersions are given. Finally, the

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.