A Method of Limiting Intermediate Values of Volume Fraction in Iterative Two-Fluid Computations

1982 ◽  
Vol 24 (4) ◽  
pp. 221-224 ◽  
Author(s):  
M. B. Carver
Keyword(s):  
Fluid Flow ◽  
Computational Analysis ◽  
Volume Fraction ◽  
Simultaneous Solution ◽  
Two Phase ◽  
Upper Limit ◽  
Satisfactory Method ◽  
Iterative Procedures ◽  
Physical Reasons ◽  
Two Fluid

Multidimensional computational analysis of fluid flow is usually done by segmented iterative methods, as the equations sets generated are too large to permit simultaneous solution. Frequently the need arises to compute values for variables which must remain bounded for physical reasons. In two-phase computation, for example, the volume fraction is restricted to values between 0 and 1, but iterative procedures often return intermediate values which violate these bounds. It is fairly straightforward to prevent negative values, however no satisfactory method of imposing the upper limit has been published. A method of smoothly applying the limit in reversible fashion is outlined in this note.

Volume fraction flux approximation in a two-fluid flow

2008 ◽  
Vol 15 (2) ◽  
pp. 169-186 ◽  
Author(s):  
S. N. Yakovenko ◽  
K. C. Chang
Keyword(s):  
Fluid Flow ◽  
Volume Fraction ◽  
Flux Approximation ◽  
Two Fluid

scholarly journals Computational investigation of liquid-solid slurry flow through an expansion in a rectangular duct

2014 ◽  
Vol 62 (3) ◽  
pp. 234-240 ◽  
Author(s):  
Gianandrea Vittorio Messa ◽  
Stefano Malavasi
Keyword(s):  
Volume Fraction ◽  
Particle Density ◽  
Fluid Model ◽  
Solid Volume Fraction ◽  
Solid Particles ◽  
Rectangular Duct ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Two Fluid Model ◽  
Two Fluid

Abstract The flow of a mixture of liquid and solid particles at medium and high volume fraction through an expansion in a rectangular duct is considered. In order to improve the modelling of the phenomenon with respect to a previous investigation (Messa and Malavasi, 2013), use is made of a two-fluid model specifically derived for dense flows that we developed and implemented in the PHOENICS code via user-defined subroutines. Due to the lack of experimental data, the two-fluid model was validated in the horizontal pipe case, reporting good agreement with measurements from different authors for fully-suspended flows. A 3D system is simulated in order to account for the effect of side walls. A wider range of the parameters characterizing the mixture (particle size, particle density, and delivered solid volume fraction) is considered. A parametric analysis is performed to investigate the role played by the key physical mechanisms on the development of the two-phase flow for different compositions of the mixture. The main focuses are the distribution of the particles in the system and the pressure recovery

Numerical Computation of Phase Separation in Two Fluid Flow

1984 ◽  
Vol 106 (2) ◽  
pp. 147-153 ◽  
Author(s):  
M. B. Carver
Keyword(s):  
Experimental Study ◽  
Fluid Flow ◽  
Phase Separation ◽  
Numerical Computation ◽  
Computational Analysis ◽  
Fluid Flows ◽  
Iterative Approach ◽  
Two Fluid

A new iterative approach is outlined for multidimensional computational analysis of two fluid flow. Parametric surveys are described to illustrate that the method rationally predicts separation of two fluid flows under gravitational and centrifugal influences. A comparison is made between behavior computed by the method, and results reported in an experimental study of air and water flowing in elbows and pipes.

scholarly journals Computational fluid simulation of non-Newtonian two-phase fluid flow through a channel with a cavity

2020 ◽  
Vol 24 (2 Part B) ◽  
pp. 1045-1054 ◽  
Author(s):  
Mehdi Ahmadi ◽  
Farsani Khosravi
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Newtonian Fluid ◽  
Volume Fraction ◽  
Staggered Grid ◽  
Mixed Solution ◽  
Two Phase ◽  
Flow Through ◽  
Velocity Pressure ◽  
Phase Fluid

In this paper, the numerical solution of non-Newtonian two-phase fluid-flow through a channel with a cavity was studied. Carreau-Yasuda non-Newtonian model which represents well the dependence of stress on shear rate was used and the effect of n index of the model and the effect of input Reynolds on the attribution of flow were considered. Governing equations were discretized using the finite volume method on staggered grid and the form of allocating flow parameters on staggered grid is based on marker and cell method. The QUICK scheme is employed for the convection terms in the momentum equations, also the convection term is discretized by using the hybrid upwind-central scheme. In order to increase the accuracy of making discrete, second order Van Leer accuracy method was used. For mixed solution of velocity-pressure field SIMPLEC algorithm was used and for pressure correction equation iteratively line-by-line TDMA solution procedure and the strongly implicit procedure was used. As the results show, by increasing Reynolds number, the time of sweeping the non-Newtonian fluid inside the cavity decreases, the velocity of Newtonian fluid increases and the pressure decreases. In the second section, by increasing n index, the velocity increases and the volume fraction of non-Newtonian fluid after cavity increases and by increasing velocity, the pressure decreases. Also changes in the velocity, pressure and volume fraction of fluids inside the channel and cavity are more sensible to changing the Reynolds number instead of changing n index.

Analysis of Powder Segregation in Powder Injection Molding

2011 ◽  
Vol 217-218 ◽  
pp. 1372-1379
Author(s):  
Yu Hui Wang ◽  
Xuan Hui Qu ◽  
Wang Feng Zhang ◽  
Yan Li
Keyword(s):  
Fluid Flow ◽  
Injection Molding ◽  
Volume Fraction ◽  
Fluid Model ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Exchange Term ◽  
Mixture Density ◽  
Two Fluid Model ◽  
Two Fluid

The powder injection molding (PIM) combines the thermoplastic and powder metallurgy technologies to manufacture intricate parts to nearly shape. The powder segregation is a special effect arising in PIM different from than the pure polymer injection. The two-fluid flow model is used to describe the flows of binder and powder so as to realize the prediction of powder segregation effect in PIM injection. To take into account binder–powder interaction, the mixture model of inter-phase exchange term is introduced in the two-fluid model. The two-fluid equations largely resemble those for single-fluid flow but are represented in terms of the mixture density and velocity. The volume fraction for each dispersed phase is solved from a phase continuity equation. As the key to calculate the phase exchange term, the drag coefficient is defined as a function of mixture viscosity. The effective viscosity of binder and powder are agreed with the additive principle. The volume fractions of binder and powder give directly the evolution of segregation during the injection course. Segregation during PIM injection was simulated by software CFX and results were compared with experimental data with good agreement. The basic reasons that caused segregation are identified as boundary effect, differences in density and viscosity of binder and powder. The segregation zones are well predicted. This showed that the two-fluid model is valid and efficient for the prediction of the segregation effects in PIM injection.

scholarly journals Numerical Study of the Effect of Magnetic Field on Nanofluid Heat Transfer in Metal Foam Environment

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Hamid Shafiee ◽  
Elaheh NikzadehAbbasi ◽  
Majid Soltani
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Porous Medium ◽  
Porous Media ◽  
Fluid Flow ◽  
Volume Fraction ◽  
Numerical Study ◽  
Computational Simulation ◽  
Thermodynamic Efficiency ◽  
Two Phase

The magnetic field can act as a suitable control parameter for heat transfer and fluid flow. It can also be used to maximize thermodynamic efficiency in a variety of fields. Nanofluids and porous media are common methods to increase heat transfer. In addition to improving heat transfer, porous media can increase pressure drop. This research is a computational simulation of the impacts of a magnetic field induced into a cylinder in a porous medium for a volume fraction of 0.2 water/Al2O3 nanofluid with a diameter of 10 μm inside the cylinder. For a wide variety of controlling parameters, simulations have been made. The fluid flow in the porous medium is explained using the Darcy-Brinkman-Forchheimer equation, and the nanofluid flow is represented utilizing a two-phase mixed approach as a two-phase flow. In addition, simulations were run in a slow flow state using the finite volume method. The mean Nusselt number and performance evaluation criteria (PEC) were studied for different Darcy and Hartmann numbers. The results show that the amount of heat transfer coefficient increases with increasing the number of Hartmann and Darcy. In addition, the composition of the nanofluid in the base fluid enhanced the PEC in all instances. Furthermore, the PEC has gained its highest value at the conditions relating to the permeable porous medium.

scholarly journals Magneto Hydro Dynamic two fluid flow of blood through stenosed artery

2016 ◽  
Vol 12 (2) ◽  
pp. 5938-5944
Author(s):  
Surendra Kumar
Keyword(s):  
Magnetic Field ◽  
Fluid Flow ◽  
Plasma Layer ◽  
Plug Flow ◽  
Flow Region ◽  
Two Phase ◽  
The Core ◽  
Stenosed Artery ◽  
Flow Through ◽  
Two Fluid

When blood flow through artery, the two-phase nature of blood as a suspension becomes  important as the diameter of the red blood cell (RBC) becomes comparable to the tube diameter. The aim of the present study  is to analyzed the effect of magnetic field on the plug flow region, shear stress in the core and plasma layer in two-fluid flow of blood through stenosed artery. Besides magnetic field, the effect of Womersley parameter, thickness of stenosis and width of plasma layer are also discussed. Generated data are analyzed and discussed through graphs.

Transient Coupled Borehole/Formation Fluid-Flow Model for Interpretation of Oil/Water Production Logs

SPE Journal ◽  
2016 ◽  
Vol 22 (01) ◽  
pp. 389-406 ◽  
Author(s):  
Amir Frooqnia ◽  
Carlos Torres-Verdín ◽  
Kamy Sepehrnoori ◽  
Rohollah Abdhollah-Pour
Keyword(s):  
Fluid Flow ◽  
Flow Model ◽  
Volume Fraction ◽  
Fluid Phase ◽  
Coupling Method ◽  
Average Pressure ◽  
Petrophysical Properties ◽  
Two Phase ◽  
Flow Models ◽  
Oil Water

Summary Interpretation of two-phase production logs (PLs) traditionally constructs borehole fluid-flow models decoupled from the physics of reservoir rocks. However, quantifying formation dynamic petrophysical properties from PLs requires simultaneous modeling of both borehole and formation fluid-flow phenomena. This paper develops a novel transient borehole/formation fluid-flow model that allows quantification of the effect of formation petrophysical properties on measurements acquired with production-logging tools (PLTs). We invoke a 1D, isothermal, two-fluid formulation to simulate borehole fluid-phase velocity, pressure, volume fraction, and density in oil/water-flow systems. The developed borehole fluid-flow model implements oil-dominant and water-dominant bubbly flow regimes with the inversion point taking place approximately when the oil volume fraction is equal to 0.5. Droplet diameter is dynamically modified to simulate interfacial drag effects, and to effectively account for variations of slip velocity in the borehole. Subsequently, a new successive iterative method interfaces the borehole and formation fluid-flow models by introducing appropriate source terms into the borehole fluid-phase mass-conservation equations. The novel iterative coupling method integrated with the developed borehole fluid-flow model allows dynamic modification of reservoir boundary conditions to accurately simulate transient behavior of borehole crossflow taking place across differentially depleted rock formations. In the case of rapid variations of near-borehole properties, frequent borehole/formation communication inevitably increases the computational time required for fluid-flow simulation. Despite this limitation, in a two-layer reservoir model penetrated by a vertical borehole, the coupling method accurately quantifies a 14% increase of volume-averaged oil-phase relative permeability of the low-pressure layer caused by through-the-borehole cross-communication of differentially depleted layers. Sensitivity analyses indicate that the alteration of near-borehole petrophysical properties primarily depends on formation average pressure, fluid-phase density contrast, and borehole-deviation angle. A practical application of the new coupled fluid-flow model is numerical simulation of borehole production measurements to estimate formation average pressure from two-phase selective-inflow-performance (SIP) analysis. This study suggests that incorporating static (shut-in) PL passes into the SIP analysis could result in misleading estimation of formation average pressure.

scholarly journals NUMERICAL MODELING OF TWO-PHASE FLOWS USING THE TWO-FLUID TWO-PRESSURE APPROACH

2004 ◽  
Vol 14 (05) ◽  
pp. 663-700 ◽  
Author(s):  
THIERRY GALLOUËT ◽  
JEAN-MARC HÉRARD ◽  
NICOLAS SEGUIN
Keyword(s):  
Volume Fraction ◽  
Local Equilibrium ◽  
Finite Volume Methods ◽  
Convective System ◽  
Two Phase Flows ◽  
Step Method ◽  
Discontinuous Solutions ◽  
Fractional Step Method ◽  
Two Phase ◽  
Two Fluid

The present paper is devoted to the computation of two-phase flows using the two-fluid approach. The overall model is hyperbolic and has no conservative form. No instantaneous local equilibrium between phases is assumed, which results in a two-velocity two-pressure model. Original closure laws for interfacial velocity and interfacial pressure are proposed. These closures allow to deal with discontinuous solutions such as shock waves and contact discontinuities without ambiguity with the definition of Rankine–Hugoniot jump relations. Each field of the convective system is investigated, providing maximum principle for the volume fraction and the positivity of densities and internal energies are ensured when focusing on the Riemann problem. Two-finite volume methods are presented, based on the Rusanov scheme and on an approximate Godunov scheme. Relaxation terms are taken into account using a fractional step method. Eventually, numerical tests illustrate the ability of both methods to compute two-phase flows.

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