Computational Fluid Dynamics Modeling of Benjamin and Taylor Bubbles in Two-Phase Flow in Pipes

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
M. Ramdin ◽  
Ruud Henkes
Keyword(s):  
Fluid Dynamics ◽  
Surface Tension ◽  
Computational Fluid Dynamics ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Bubble Velocity ◽  
Multiphase Model ◽  
Dynamics Modeling ◽  
Two Phase ◽  
Eotvos Number

Abstract There is an increasing interest in applying three-dimensional computational fluid dynamics (CFD) for multiphase flow transport in pipelines, e.g., in the oil and gas industry. In this study, the volume of fluid (VOF) multiphase model in a commercial CFD code was used to benchmark the capabilities. Two basic flow structures, namely, the Benjamin bubble and the Taylor bubble, are considered. These two structures are closely related to the slug flow regime, which is a common flow pattern encountered in multiphase transport pipelines. After nondimensionalization, the scaled bubble velocity (Froude number) is only dependent on the Reynolds number and on the Eötvös number, which represent the effect of viscosity and surface tension, respectively. Simulations were made for a range of Reynolds numbers and Eötvös numbers (including the limits of vanishing viscosity and surface tension), and the results were compared with the existing experiments and analytical expressions. Overall, there is very good agreement. An exception is the simulation for the 2D Benjamin bubble at a low Eötvös number (i.e., large surface tension effect) which deviates from the experiments, even at a refined numerical grid.

CFD for Multiphase Flow Transport in Pipelines

2011 ◽  
Author(s):  
M. Ramdin ◽  
R. A. W. M. Henkes
Keyword(s):  
Surface Tension ◽  
Multiphase Flow ◽  
Oil And Gas ◽  
Three Dimensional ◽  
Oil And Gas Industry ◽  
Bubble Velocity ◽  
Multiphase Model ◽  
Gas Industry ◽  
Flow Transport ◽  
Numerical Grid

There is an increasing interest in applying three-dimensional Computational Fluid Dynamics (CFD) for multiphase flow transport in pipelines, e.g. in the oil and gas industry. In this study the Volume of Fluid (VOF) multiphase model in the commercial CFD code FLUENT was used to benchmark the capabilities. Two basic flow structures, namely the Benjamin bubble and the Taylor bubble, are considered. These two structures are closely related to the slug flow regime, which is a common flow pattern encountered in multiphase transport pipelines. After non-dimensionalization, the scaled bubble velocity (Froude number) is only dependent on the Reynolds number and on the Eo¨tvo¨s number, which represent the effect of viscosity and surface tension, respectively. Simulations were made for a range of Reynolds numbers and Eo¨tvo¨s numbers (including the limits of vanishing viscosity and surface tension), and the results were compared with existing experiments and analytical expressions. Overall there is very good agreement. An exception is the simulation for the 2D Benjamin bubble at low Eo¨tvo¨s number (i.e. large surface tension effect) which deviates from the experiments, even at a refined numerical grid.

Evaluation of Flow Characteristics in an Oil-Water Separator Using Computational Fluid Dynamics

2020 ◽  
Author(s):  
Terry Potter ◽  
Tathagata Acharya
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Residence Time ◽  
Water Volume ◽  
Multiphase Model ◽  
Two Phase ◽  
Water Separator ◽  
Oil Water ◽  
Simulation Results ◽  
Water Cut

Abstract Multiphase separators on production platforms are among the first equipment through which well fluids flow. Based on functionality, multiphase separators can either be two-phase that separate oil from water, or three-phase that separate oil, natural gas, and water. Separator performances are often evaluated using mean residence time (MRT) of the hydrocarbon phase. MRT is defined as the amount of time a given phase stays inside the separator. On field, operators usually measure MRT as the ratio of active volume occupied by each phase to the phase volumetric flowrate. However, this method may involve significant errors as the oil-water interface height is obtained using level controllers and the volume occupied by each phase is calculated assuming the interface can be extrapolated from the weir back to the separator inlet. In this study, authors perform computational fluid dynamics (CFD) on a two-phase horizontal separator to evaluate MRT as a function of varying water volume flowrates (water-cut) in a mixture of water and oil. The authors use residence time distributions (RTD) to obtain MRT at each water-cut — a method that results in significantly more accurate results than the regular method used by operators. The numerical model is developed with commercial software package ANSYS Fluent. The code uses the Eulerian multiphase model along with the k-ε turbulence model. The simulation results show agreement with experiments performed by previous researchers. Additional simulations are performed to assess the effect of various separator internals on separator performance. Simulation results suggest that the model developed in this study can be used to predict performances of two-phase liquid-liquid separators with reasonable accuracy and will be useful towards their design to improve performances under various inlet flow conditions.

Computational Fluid Dynamics Modeling of Gas–Liquid Cylindrical Cyclones, Geometrical Analysis

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Juan Carlos Berrio ◽  
Eduardo Pereyra ◽  
Nicolas Ratkovich
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Cfd Modeling ◽  
Nozzle Geometry ◽  
Geometrical Parameters ◽  
Experimental Setup ◽  
Dynamics Modeling ◽  
Two Phase ◽  
Mean Square Errors

The gas–liquid cylindrical cyclone (GLCC) is a widely used alternative for gas–liquid conventional separation. Besides its maturity, the effect of some geometrical parameters over its performance is not fully understood. The main objective of this study is to use computational fluid dynamics (CFD) modeling in order to evaluate the effect of geometrical modifications in the reduction of liquid carry over (LCO) and gas carry under (GCU). Simulations for two-phase flow were carried out under zero net liquid flow, and the average liquid holdup was compared with Kanshio (Kanshio, S., 2015, “Multiphase Flow in Pipe Cyclonic Separator,” Ph.D. thesis, Cranfield University, Cranfield, UK) obtaining root-mean-square errors around 13% between CFD and experimental data. An experimental setup, in which LCO data were acquired, was built in order to validate a CFD model that includes both phases entering to the GLCC. An average discrepancy below 6% was obtained by comparing simulations with experimental data. Once the model was validated, five geometrical variables were tested with CFD. The considered variables correspond to the inlet configuration (location and inclination angle), the effect of dual inlet, and nozzle geometry (diameter and area reduction). Based on the results, the best configuration corresponds to an angle of 27 deg, inlet location 10 cm above the center, a dual inlet with 20 cm of spacing between both legs, a nozzle of 3.5 cm of diameter, and a volute inlet of 15% of pipe area. The combination of these options in the same geometry reduced LCO by 98% with respect to the original case of the experimental setup. Finally, the swirling decay was studied with CFD showing that liquid has a greater impact than the gas flowrate.

Analysis and Modeling of Liquid Holdup in Low Liquid Loading Two-Phase Flow Using Computational Fluid Dynamics and Experimental Data

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Miguel Ballesteros ◽  
Nicolás Ratkovich ◽  
Eduardo Pereyra
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Oil And Gas ◽  
Operating Conditions ◽  
Liquid Holdup ◽  
Liquid Loading ◽  
Two Phase ◽  
Acceptable Error ◽  
Pharmaceutical Industries

Abstract Low liquid loading flow occurs very commonly in the transport of any kind of wet gas, such as in the oil and gas, the food, and the pharmaceutical industries. However, most studies that analyze this type of flow do not cover actual industry fluids and operating conditions. This study focused then on modeling this type of flow in medium-sized (6-in [DN 150] and 10-in [DN 250]) pipes, using computational fluid dynamics (CFD) simulations. When comparing with experimental data from the University of Tulsa, the differences observed between experimental and CFD data for the liquid holdup and the pressure drop seemed to fall within acceptable error, around 20%. Additionally, different pipe sections from a Colombian gas pipeline were simulated with a natural gas-condensate mixture to analyze the effect of pipe inclination and operation variables on liquid holdup, in real industry conditions. It was noticed that downward pipe inclinations favored smooth stratified flow and decreased liquid holdup in an almost linear fashion, while upward inclinations generated unsteady wavy flows, or even a possible annular flow, and increased liquid holdup and liquid entrainment into the gas phase.

Computational Fluid Dynamics Modeling of Two-Phase Flow in an Adiabatic Capillary Tube

2014 ◽  
Vol 7 (1) ◽  
Author(s):  
Yogesh K. Prajapati ◽  
Manabendra Pathak ◽  
Mohd. Kaleem Khan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Capillary Tube ◽  
Mass Transfer Rate ◽  
Dynamics Modeling ◽  
Flow Properties ◽  
Two Phase ◽  
Flow Turbulence ◽  
R 134A ◽  
Volume Method

In this work computational fluid dynamics (CFD) technique has been used to analyze the detailed flow structures of refrigerant R-134a in an adiabatic capillary tube using volume of fluid based finite volume method. Also, an attempt has been made to understand the flashing phenomenon within the adiabatic capillary tube. A source term has been incorporated in the governing equations to model the mass transfer rate from liquid phase to vapor phase during the flashing process. The developed numerical model has been validated with the available experimental data. The unsteady variations of flow properties such as velocity, void fraction distributions, and flow turbulence across the cross section and at different axial length of the tube have been presented. It has been observed that flashing initiates from the wall of the tube. With the inception of vapor, the flow properties change drastically with very short transient period. As far as flow turbulence is concerned, the role of flashing parameter seems to be stronger than internal tube wall roughness.

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