Experience in using a numerical scheme with artificial viscosity at solving the Riemann problem for a multi-fluid model of multiphase flow

2018 ◽  
Author(s):  
S. V. Bulovich ◽  
E. M. Smirnov
Keyword(s):  
Multiphase Flow ◽  
Riemann Problem ◽  
Numerical Scheme ◽  
Fluid Model ◽  
Artificial Viscosity

Stability of a Thermodynamically Coherent Multiphase Model

2003 ◽  
Vol 13 (10) ◽  
pp. 1463-1487
Author(s):  
B. Després ◽  
F. Lagoutière ◽  
D. Ramos
Keyword(s):  
Conservation Laws ◽  
Numerical Scheme ◽  
Fluid Model ◽  
Multiphase Model ◽  
Physical Domain ◽  
Rarefaction Waves ◽  
Phase Models ◽  
The Stability ◽  
Multi Phase ◽  
Dimension One

We analyze a hyperbolic system of conservation laws in dimension one, which is a drastic simplification of a multi-phase or multi-velocity fluid model. The physical domain of hyperbolicity is bounded, which is a characteristic of multi-phase models. Our main result is the stability of the domain of hyperbolicity. Due to the degeneracy of the model on the boundary of the hyperbolicity domain, rarefaction waves are not unique. We also propose a numerical scheme for approximate resolution of the model and prove the stability of this scheme.

Reactor Safety Analysis Based on a Developed Two-Phase Compressible Flow Simulation

Volume 1 ◽  
2004 ◽  
Author(s):  
A. F. Nowakowski ◽  
B. V. Librovich ◽  
L. Lue
Keyword(s):  
Multiphase Flow ◽  
Compressible Flow ◽  
Fluid Model ◽  
Numerical Technique ◽  
Computational Simulation ◽  
Safety Analysis ◽  
State Equations ◽  
Pressure Relief ◽  
Two Phase ◽  
Two Phases

The direct numerical simulation of multiphase flow is a challenging research topic with various key applications. In the present work, a computational simulation of multi-phase compressible flow has been proposed for safety analysis of chemical reactors. The main objective of a pressure relief system is to prevent accidents occurring from over pressurisation of the reactor. We are particularly interested in understanding the phenomena associated with emergency pressure relief systems for batch-type reactors and storage vessels. Existence of multiphase flow is significantly influenced by the interface between the phases and the associated discontinuities across the phase. The approach, which builds on the method first introduced by Saurel and Abgrall [1], was developed for solving two-phase compressible flow problems. Each phase is separately described by conservation equations. The interactions between two phases appear in the basic equations as transfer terms across the interface. The equations are complemented by state equations for the two phases and by additional correlations for the right-hand side coupling terms. The method is able to deal with multiphase mixtures and interface problems between compressible fluids. The key difference compared to classical two-fluid model is the presence of separate pressures fields associated with phases and introduction of pressure and velocity relaxation procedures. The relaxation operators tackle the boundary conditions at the interface and consequently the model is valid for fluid mixtures, as well as for pure fluids. The numerical technique requires the system to be decomposed and involves a non-conservative hyperbolic solver, an instantaneous pressure relaxation procedure and source term operators. The solution is obtained by succession of integrators using a second-order accurate scheme. The ultimate goal of this research is to use the method for studying the venting problem in reactor systems after verifying its performance on a series of standardised test cases documented in the literature.

Analysis of Centrifugal Pump Performing Under Two-Phase Flow Using Bleeding System

2001 ◽  
Author(s):  
M. A. Zaher
Keyword(s):  
Multiphase Flow ◽  
Centrifugal Pump ◽  
Fluid Model ◽  
Energy Requirement ◽  
Two Phase ◽  
Pump Test ◽  
Pump Head ◽  
Two Fluid Model ◽  
Specific Energy Requirement ◽  
Two Fluid

Abstract A one dimensional two fluid model is used to study the performance of a centrifugal pump. Pumping of two-phase products in oil/geothermal industry offered a special multiphase pump. Test with different suction void fraction was used to predict the two-phase pump head data for two scales of pumps. With the new arrangement of bleeding and correct impeller design, a radical solution is offered to handle a multiphase flow. The physical mechanism responsible for transporting multiphase flow on efficiency, specific energy requirement and flow rate were also investigated.

Development of Transient Mechanistic Three-Phase Flow Model for Wellbores

SPE Journal ◽  
2016 ◽  
Vol 22 (01) ◽  
pp. 374-388 ◽  
Author(s):  
Mahdy Shirdel ◽  
Kamy Sepehrnoori
Keyword(s):  
Multiphase Flow ◽  
Flow Model ◽  
Fluid Model ◽  
Phase Flow ◽  
Complex Flow ◽  
Flow Models ◽  
Drift Flux Model ◽  
Three Phase ◽  
Three Phase Flow ◽  
Two Fluid

Summary Multiphase flow models have been widely used for downhole-gauging and production logging analysis in the wellbores. Coexistence of hydrocarbon fluids with water in production wells yields a complex flow system that requires a three-phase flow model for better characterizing the flow and analyzing measured downhole data. In the past few decades, many researchers and commercial developers in the petroleum industry have aggressively expanded development of robust multiphase flow models for the wellbore. However, many of the developed models apply homogeneous-flow models with limited assumptions for slippage between gas and liquid bulks or use purely two-fluid models. In this paper, we propose a new three-phase flow model that consists of a two-fluid model between liquid and gas and a drift-flux model between water and oil in the liquid phase. With our new method, we improve the simplifying assumptions for modeling oil, water, and gas multiphase flow in wells, which can be advantageous for better downhole flow characterization and phase separations in gravity-dominated systems. Furthermore, we developed semi-implicit and nearly implicit numerical algorithms to solve the system of equations. We discuss the stepwise-development procedures for these methods along with the assumptions in our flow model. We verify our model results against analytical solutions for the water faucet problem and phase redistribution, field data, and a commercial simulator. Our model results show very good agreement with benchmarks in the data.

Experimental and Numerical Approach to Enlargement and Determination of Performance of Primary Sedimentation Basin

2007 ◽  
Author(s):  
A. M. Razmi ◽  
B. Firoozabadi
Keyword(s):  
Numerical Scheme ◽  
Fluid Model ◽  
Settling Tank ◽  
Numerical Approach ◽  
Acoustic Doppler Velocimeter ◽  
Two Phase ◽  
Optimum Position ◽  
Volume Of Fluid Model ◽  
Volume Method

In the present study, the presence of a baffle and its effect on the hydrodynamics of the flow in a primary settling tank has been investigated experimentally by ADV (Acoustic Doppler Velocimeter). On the other hand, the characteristics of this flow field were simulated by an unsteady two-phase finite volume method, and VOF (Volume of Fluid) model; and results were evaluated by the experimental data. The numerical calculation performed by using k–ε RNG model agrees well with experiments. It depicts the ability of this method in predicting the velocity profile and flow structure. In addition, the optimum position of the baffle to achieve the best performance of the tank was determined by applying the above mentioned numerical scheme.

Simulation of Multiphase Flows in Complex Geometry Using a Hybrid Method Combining the Multi-Fluid and the Volume-of-Fluid (VOF) Approaches

2002 ◽  
Author(s):  
Jaehoon Han ◽  
Ales Alajbegovic
Keyword(s):  
Multiphase Flow ◽  
Hybrid Method ◽  
Multiphase Flows ◽  
Complex Geometry ◽  
Fluid Model ◽  
Simple Algorithm ◽  
Volume Of Fluid ◽  
Vof Method ◽  
Computational Method ◽  
Small Scale

A computational method combining the multi-fluid and the Volume-of-Fluid (VOF) approaches is presented to simulate industrial multiphase flows in complex geometry. This method is particularly applicable for flows where well-defined interfaces between different phases/fluids co-exist with small-scale multiphase structures. The interfaces in relatively large scales (that can be accurately resolved on a computational mesh with a practical size) are tracked by the VOF method, whereas the small scale multiphase flow structures (that are too computationally expensive to be explicitly tracked by the VOF method) are accounted for by using the multi-fluid approach. In order to provide more computational flexibility, any two of the phases tracked by the multi-fluid approach can either have different velocities (two-fluid model) or share the same velocities (equilibrium model). The hybrid method presented here enables efficient simulation of complex flows with multiple phases/fluids on arbitrary-shaped unstructured meshes. It is fully implemented in the commercial CFD software, AVL FIRE/SWIFT. The governing equations are discretized based on a finite volume method (FVM) and the pressure field is obtained using the SIMPLE algorithm. The effect of surface tension is also included for the phases tracked by the VOF method using a Continuum Surface Force (CSF) model. Application to a well-established example of multiphase flow—a Taylor bubble rising inside a stagnant liquid—is presented to demonstrate the capability of the method.

Phase Field Method for Simulation of Multiphase Flow

2011 ◽  
Author(s):  
Harish Ganapathy ◽  
Ebrahim Al-Hajri ◽  
Michael M. Ohadi
Keyword(s):  
Multiphase Flow ◽  
Phase Field ◽  
Predictive Accuracy ◽  
Fluid Model ◽  
Thin Liquid Film ◽  
Field Method ◽  
Phase Field Method ◽  
Formation Mechanisms ◽  
Two Phase ◽  
Taylor Flow

The present paper reports a comprehensive study on the numerical simulation of Taylor flow in microchannels by the phase field method. Additionally, a comparative study was also performed against an alternative volume of fluid model based on which the phase field method was found to be more advantageous in key aspects such as the absence of unphysical interfacial pressure oscillations and the ability to account for variations in the surface tension force and thus predict several bubble lengths under constant flow conditions while observing the physics of homogeneous two-phase flow. Different bubble formation mechanisms were simulated and compared against experimental findings in literature. The simulation of a thin liquid film at the channel wall was found to be a limitation of most works pertaining to Taylor flow, including the present. This was ascribed to be more likely due to limited dimensional and spatial resolution as well as inaccurate contact angle dynamics rather than limitations of the modeling approach itself. The effect of wall adhesion was studied with respect to the flow and pressure field in the channel. A validation of the model was achieved through a favorable comparison of the numerically predicted gas void fraction and bubble lengths with existing models and correlations. On the whole, the phase field method was concluded to have improved predictive accuracy with respect to certain aspects as compared to conventional multiphase flow models.

An Artificial Viscosity for the III-Posed One-Dimensional Incompressible Two-Fluid Model

2014 ◽  
Vol 185 (3) ◽  
pp. 296-308 ◽  
Author(s):  
William D. Fullmer ◽  
Sang Yong Lee ◽  
Martin A. Lopez De Bertodano
Keyword(s):  
Fluid Model ◽  
Artificial Viscosity ◽  
One Dimensional ◽  
Two Fluid Model ◽  
Two Fluid
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