**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**39

# Search results for: two-phase flow

##### 39 CFD Modeling of Mixing Enhancement in a Pitted Micromixer by High Frequency Ultrasound Waves

**Authors:**
Faezeh Mohammadi,
Ebrahim Ebrahimi,
Neda Azimi

**Abstract:**

Use of ultrasound waves is one of the techniques for increasing the mixing and mass transfer in the microdevices. Ultrasound propagation into liquid medium leads to stimulation of the fluid, creates turbulence and so increases the mixing performance. In this study, CFD modeling of two-phase flow in a pitted micromixer equipped with a piezoelectric with frequency of 1.7 MHz has been studied. CFD modeling of micromixer at different velocity of fluid flow in the absence of ultrasound waves and with ultrasound application has been performed. The hydrodynamic of fluid flow and mixing efficiency for using ultrasound has been compared with the layout of no ultrasound application. The result of CFD modeling shows well agreements with the experimental results. The results showed that the flow pattern inside the micromixer in the absence of ultrasound waves is parallel, while when ultrasound has been applied, it is not parallel. In fact, propagation of ultrasound energy into the fluid flow in the studied micromixer changed the hydrodynamic and the forms of the flow pattern and caused to mixing enhancement. In general, from the CFD modeling results, it can be concluded that the applying ultrasound energy into the liquid medium causes an increase in the turbulences and mixing and consequently, improves the mass transfer rate within the micromixer.

**Keywords:**
CFD modeling,
ultrasound,
mixing,
mass transfer.

##### 38 Transient Analysis of Central Region Void Fraction in a 3x3 Rod Bundle under Bubbly and Cap/Slug Flows

**Authors:**
Ya-Chi Yu,
Pei-Syuan Ruan,
Shao-Wen Chen,
Yu-Hsien Chang,
Jin-Der Lee,
Jong-Rong Wang,
Chunkuan Shih

**Abstract:**

_{f}=0.094 m/s), two different superficial air velocities (J

_{g}=0.094 m/s and 0.236 m/s) were tested and presented, which were corresponding to the flow conditions of bubbly flows and cap/slug flows, respectively. The time averaged central region void fraction was obtained as 0.109-0.122 with 0.028 standard deviation for the selected bubbly flow and 0.188-0.221with 0.101 standard deviation for the selected cap/slug flow, respectively. Through Fast Fourier Transform (FFT) analysis, no clear frequency peak was found in bubbly flow, while two dominant frequencies were identified around 1.6 Hz and 2.5 Hz in the present cap/slug flow.

**Keywords:**
Central region,
rod bundles,
transient void fraction,
two-phase flow.

##### 37 Numerical Investigation of Multiphase Flow in Pipelines

**Authors:**
Gozel Judakova,
Markus Bause

**Abstract:**

**Keywords:**
Discontinuous Galerkin method,
Euler system,
inviscid two-fluid model,
streamline upwind Petrov-Galerkin
method,
two-phase flow.

##### 36 A Two-Phase Flow Interface Tracking Algorithm Using a Fully Coupled Pressure-Based Finite Volume Method

**Authors:**
Shidvash Vakilipour,
Scott Ormiston,
Masoud Mohammadi,
Rouzbeh Riazi,
Kimia Amiri,
Sahar Barati

**Abstract:**

**Keywords:**
Coupled solver,
gravitational force,
interface tracking,
Reynolds number to Froude number,
two-phase flow.

##### 35 Simulation of Ammonia-Water Two Phase Flow in Bubble Pump

**Authors:**
Jemai Rabeb,
Benhmidene Ali,
Hidouri Khaoula,
Chaouachi Bechir

**Abstract:**

The diffusion-absorption refrigeration cycle consists of a generator bubble pump, an absorber, an evaporator and a condenser, and usually operates with ammonia/water/ hydrogen or helium as the working fluid. The aim of this paper is to study the stability problem a bubble pump. In fact instability can caused a reduction of bubble pump efficiency. To achieve this goal, we have simulated the behaviour of two-phase flow in a bubble pump by using a drift flow model. Equations of a drift flow model are formulated in the transitional regime, non-adiabatic condition and thermodynamic equilibrium between the liquid and vapour phases. Equations resolution allowed to define void fraction, and liquid and vapour velocities, as well as pressure and mixing enthalpy. Ammonia-water mixing is used as working fluid, where ammonia mass fraction in the inlet is 0.6. Present simulation is conducted out for a heating flux of 2 kW/m² to 5 kW/m² and bubble pump tube length of 1 m and 2.5 mm of inner diameter. Simulation results reveal oscillations of vapour and liquid velocities along time. Oscillations decrease with time and with heat flux. For sufficient time the steady state is established, it is characterised by constant liquid velocity and void fraction values. However, vapour velocity does not have the same behaviour, it increases for steady state too. On the other hand, pressure drop oscillations are studied.

**Keywords:**
Bubble pump,
drift flow model,
instability,
simulation.

##### 34 Experimental and Graphical Investigation on Oil Recovery by Buckley-Leveret Theory

**Authors:**
Khwaja Naweed Seddiqi,
Zabihullah Mahdi,
Shigeo Honma

**Abstract:**

**Keywords:**
Petroleum reservoir engineering,
relative permeability,
two-phase flow,
immiscible displacement in porous media,
steady-state method,
waterflooding.

##### 33 The Effect of Development of Two-Phase Flow Regimes on the Stability of Gas Lift Systems

**Authors:**
Khalid. M. O. Elmabrok,
M. L. Burby,
G. G. Nasr

**Abstract:**

**Keywords:**
Gas lift instability,
bubble forming,
bubble collapsing,
image processing.

##### 32 Streamwise Vorticity in the Wake of a Sliding Bubble

**Authors:**
R. O’Reilly Meehan,
D. B. Murray

**Abstract:**

**Keywords:**
Bubbly flow,
particle image velocimetry,
two-phase
flow,
wake structures.

##### 31 Prediction of Air-Water Two-Phase Frictional Pressure Drop Using Artificial Neural Network

**Authors:**
H. B. Mehta,
Vipul M. Patel,
Jyotirmay Banerjee

**Abstract:**

The present paper discusses the prediction of gas-liquid two-phase frictional pressure drop in a 2.12 mm horizontal circular minichannel using Artificial Neural Network (ANN). The experimental results are obtained with air as gas phase and water as liquid phase. The superficial gas velocity is kept in the range of 0.0236 m/s to 0.4722 m/s while the values of 0.0944 m/s, 0.1416 m/s and 0.1889 m/s are considered for superficial liquid velocity. The experimental results are predicted using different Artificial Neural Network (ANN) models. Networks used for prediction are radial basis, generalised regression, linear layer, cascade forward back propagation, feed forward back propagation, feed forward distributed time delay, layer recurrent, and Elman back propagation. Transfer functions used for networks are Linear (PURELIN), Logistic sigmoid (LOGSIG), tangent sigmoid (TANSIG) and Gaussian RBF. Combination of networks and transfer functions give different possible neural network models. These models are compared for Mean Absolute Relative Deviation (MARD) and Mean Relative Deviation (MRD) to identify the best predictive model of ANN.

**Keywords:**
Minichannel,
Two-Phase Flow,
Frictional Pressure Drop,
ANN,
MARD,
MRD.

##### 30 A Coupled Model for Two-Phase Simulation of a Heavy Water Pressure Vessel Reactor

**Authors:**
Damian Ramajo,
Santiago Corzo,
Norberto Nigro

**Abstract:**

**Keywords:**
CFD,
PHWR,
Thermo-hydraulic,
Two-phase flow.

##### 29 Numerical Simulation of Three-Dimensional Cavitating Turbulent Flow in Francis Turbines with ANSYS

**Authors:**
Raza Abdulla Saeed

**Abstract:**

**Keywords:**
Computational Fluid Dynamics,
Hydraulic Francis
Turbine,
Numerical Simulation,
Two-Phase Mixture Cavitation
Model.

##### 28 Numerical Simulation of Free Surface Water Wave for the Flow around NACA 0012 Hydrofoil and Wigley Hull Using VOF Method

**Authors:**
Saadia Adjali,
Omar Imine,
Mohammed Aounallah,
Mustapha Belkadi

**Abstract:**

**Keywords:**
Free surface flows,
Breaking waves,
Boundary
layer,
Wigley hull,
Volume of fluid.

##### 27 Numerical Simulation of Free Surface Water Wave for the Flow around NACA 0012 Hydrofoil and Wigley Hull Using VOF Method

**Authors:**
Saadia Adjali,
Omar Imine,
Mohammed Aounallah,
Mustapha Belkadi

**Abstract:**

**Keywords:**
Free surface flows,
breaking waves,
boundary layer,
Wigley hull,
volume of fluid.

##### 26 An Experimental Investigation on the Droplet Behavior Impacting a Hot Surface above the Leidenfrost Temperature

**Authors:**
Khaleel Sami Hamdan,
Dong-Eok Kim,
Sang-Ki Moon

**Abstract:**

An appropriate model to predict the size of the droplets resulting from the break-up with the structures will help in a better understanding and modeling of the two-phase flow calculations in the simulation of a reactor core loss-of-coolant accident (LOCA). A droplet behavior impacting on a hot surface above the Leidenfrost temperature was investigated. Droplets of known size and velocity were impacted to an inclined plate of hot temperature, and the behavior of the droplets was observed by a high-speed camera. It was found that for droplets of Weber number higher than a certain value, the higher the Weber number of the droplet the smaller the secondary droplets. The COBRA-TF model over-predicted the measured secondary droplet sizes obtained by the present experiment. A simple model for the secondary droplet size was proposed using the mass conservation equation. The maximum spreading diameter of the droplets was also compared to previous correlations and a fairly good agreement was found. A better prediction of the heat transfer in the case of LOCA can be obtained with the presented model.

**Keywords:**
Break-up,
droplet,
impact,
inclined hot plate,
Leidenfrost temperature,
LOCA.

##### 25 Oil-Water Two-Phase Flow Characteristics in Horizontal Pipeline – A Comprehensive CFD Study

**Authors:**
Anand B. Desamala,
Ashok Kumar Dasamahapatra,
Tapas K. Mandal

**Abstract:**

In the present work, detailed analysis on flow characteristics of a pair of immiscible liquids through horizontal pipeline is simulated by using ANSYS FLUENT 6.2. Moderately viscous oil and water (viscosity ratio = 107, density ratio = 0.89 and interfacial tension = 0.024 N/m) have been taken as system fluids for the study. Volume of Fluid (VOF) method has been employed by assuming unsteady flow, immiscible liquid pair, constant liquid properties, and co-axial flow. Meshing has been done using GAMBIT. Quadrilateral mesh type has been chosen to account for the surface tension effect more accurately. From the grid independent study, we have selected 47037 number of mesh elements for the entire geometry. Simulation successfully predicts slug, stratified wavy, stratified mixed and annular flow, except dispersion of oil in water, and dispersion of water in oil. Simulation results are validated with horizontal literature data and good conformity is observed. Subsequently, we have simulated the hydrodynamics (viz., velocity profile, area average pressure across a cross section and volume fraction profile along the radius) of stratified wavy and annular flow at different phase velocities. The simulation results show that in the annular flow, total pressure of the mixture decreases with increase in oil velocity due to the fact that pipe cross section is completely wetted with water. Simulated oil volume fraction shows maximum at the centre in core annular flow, whereas, in stratified flow, maximum value appears at upper side of the pipeline. These results are in accord with the actual flow configuration. Our findings could be useful in designing pipeline for transportation of crude oil.

**Keywords:**
CFD,
Horizontal pipeline,
Oil-water flow,
VOF technique.

##### 24 Analysis of Liquid Nitrogen Spray Atomization Characteristics by Internal-Mixing Atomizers

**Authors:**
Zhang Lei,
Liu Gaotong

**Abstract:**

The atomization effect is an important factor of the heat transfer of liquid nitrogen spray. In this paper, two kinds of internal-mixing twin-fluid atomizers were design. According to the fracture theory and fluid mechanics, the model is established to simulate atomization effect. The results showed that: Internal-mixing atomizers, with the liquid nitrogen atomization size from 20um to 40um, have superior performance. Y-jet atomizer spray speed is greater than Multi-jet atomizer, and it can improve the efficiency of heat transfer between the liquid nitrogen and its spray object. Multi-jet atomizer atomization cone angle is about 30°, Y-jet atomizer atomization cone angle is about 20°. During atomizer selection, the size of the heat transfer area should be considered.

**Keywords:**
Atomization,
two-phase flow,
atomizer,
heat transfer.

##### 23 Two Phase Frictional Pressure Drop of Carbon Dioxide in Horizontal Micro Tubes

**Authors:**
M. Tarawneh

**Abstract:**

**Keywords:**
Two-phase flow,
frictional pressure drop,
horizontalmicro tube,
carbon dioxide,
condensers.

##### 22 CFD Simulation and Validation of Flow Pattern Transition Boundaries during Moderately Viscous Oil-Water Two-Phase Flow through Horizontal Pipeline

**Authors:**
Anand B. Desamala,
Anjali Dasari,
Vinayak Vijayan,
Bharath K. Goshika,
Ashok K. Dasmahapatra,
Tapas K. Mandal

**Abstract:**

**Keywords:**
CFD simulation,
flow pattern transition,
moderately viscous oil-water flow,
prediction of flow transition boundary,
VOF technique.

##### 21 The Analysis of Two-Phase Jet in Pneumatic Powder Injection into Liquid Alloys

**Authors:**
J. Jezierski,
K. Janerka

**Abstract:**

**Keywords:**
injection lance,
liquid metal,
powder injection,
slip
velocity,
two-phase jet

##### 20 Numerical Analysis of Oil-Water Transport in Horizontal Pipes Using 1D Transient Mathematical Model of Thermal Two-Phase Flows

**Authors:**
Evgeniy Burlutskiy

**Abstract:**

**Keywords:**
Mathematical model,
Oil-Water,
Pipe flows.

##### 19 On the Numerical Approach for Simulating Thermal Hydraulics under Seismic Condition

**Authors:**
Tadashi Watanabe

**Abstract:**

**Keywords:**
Two-phase flow,
simulation,
seismic condition,
moving grid,
oscillating acceleration,
interfacial area

##### 18 Effect of Various Nozzle Profiles on Performance of a Two Phase Flow Jet Pump

**Authors:**
Vishnu Prasad Sharma,
S. Kumaraswamy,
A. Mani

**Abstract:**

This paper reports on the results of experimental investigations on the performance of a jet pump operated under selected primary flows to optimize the related parameters. For this purpose a two-phase flow jet pump was used employing various profiles of nozzles as the primary device which was designed, fabricated and used along with the combination of mixing tube and diffuser. The profiles employed were circular, conical, and elliptical. The diameter of the nozzle used was 4 mm. The area ratio of the jet pump was 0.16. The test facility created for this purpose was an open loop continuous circulation system. Performance of the jet pump was obtained as iso-efficiency curves on characteristic curves drawn for various water flow rates. To perform the suction capability, evacuation test was conducted at best efficiency point for all the profiles.

**Keywords:**
Evacuation test,
jet pump,
nozzle profile,
nozzle
spacing,
performance test,
two phase flow

##### 17 Nonlinear Thermal Hydraulic Model to Analyze Parallel Channel Density Wave Instabilities in Natural Circulation Boiling Water Reactor with Asymmetric Power Distribution

**Authors:**
Sachin Kumar,
Vivek Tiwari,
Goutam Dutta

**Abstract:**

**Keywords:**
Asymmetric power distribution,
Density wave oscillations,
In-phase and out-of-phase modes of instabilities,
Natural circulation boiling water reactor

##### 16 Simulation of Sloshing behavior using Moving Grid and Body Force Methods

**Authors:**
Tadashi Watanabe

**Abstract:**

**Keywords:**
Two-phase flow,
simulation,
oscillation,
moving grid,
body force

##### 15 Use of Time-Depend Effects for Mixing and Separation of the Two-Phase Flows

**Authors:**
N. B. Fedosenko,
A.A Iatcenko,
S.A. Levanov

**Abstract:**

**Keywords:**
Two-phase,
mixing,
separating,
flow control

##### 14 Slug Tracking Simulation of Severe Slugging Experiments

**Authors:**
Tor Kindsbekken Kjeldby,
Ruud Henkes,
Ole Jørgen Nydal

**Abstract:**

Experimental data from an atmospheric air/water terrain slugging case has been made available by the Shell Amsterdam research center, and has been subject to numerical simulation and comparison with a one-dimensional two-phase slug tracking simulator under development at the Norwegian University of Science and Technology. The code is based on tracking of liquid slugs in pipelines by use of a Lagrangian grid formulation implemented in Cµ by use of object oriented techniques. An existing hybrid spatial discretization scheme is tested, in which the stratified regions are modelled by the two-fluid model. The slug regions are treated incompressible, thus requiring a single momentum balance over the whole slug. Upon comparison with the experimental data, the period of the simulated severe slugging cycle is observed to be sensitive to slug generation in the horizontal parts of the system. Two different slug initiation methods have been tested with the slug tracking code, and grid dependency has been investigated.

**Keywords:**
Hydrodynamic initiation,
slug tracking,
terrain slugging,
two-fluid model,
two-phase flow.

##### 13 GPU Implementation for Solving in Compressible Two-Phase Flows

**Authors:**
Sheng-Hsiu Kuo,
Pao-Hsiung Chiu,
Reui-Kuo Lin,
Yan-Ting Lin

**Abstract:**

A one-step conservative level set method, combined with a global mass correction method, is developed in this study to simulate the incompressible two-phase flows. The present framework do not need to solve the conservative level set scheme at two separated steps, and the global mass can be exactly conserved. The present method is then more efficient than two-step conservative level set scheme. The dispersion-relation-preserving schemes are utilized for the advection terms. The pressure Poisson equation solver is applied to GPU computation using the pCDR library developed by National Center for High-Performance Computing, Taiwan. The SMP parallelization is used to accelerate the rest of calculations. Three benchmark problems were done for the performance evaluation. Good agreements with the referenced solutions are demonstrated for all the investigated problems.

**Keywords:**
Conservative level set method,
two-phase flow,
dispersion-relation-preserving,
graphics processing unit (GPU),
multi-threading.

##### 12 Comparison of Three Turbulence Models in Wear Prediction of Multi-Size Particulate Flow through Rotating Channel

**Authors:**
Pankaj K. Gupta,
Krishnan V. Pagalthivarthi

**Abstract:**

**Keywords:**
Rotating channel,
maximum wear rate,
multi-sizeparticulate flow,
k −ε turbulence models.

##### 11 Numerical Simulation of Cavitation and Aeration in Discharge Gated Tunnel of a Dam Based on the VOF Method

**Authors:**
Razieh Jalalabadi,
Norouz Mohammad Nouri

**Abstract:**

**Keywords:**
Aeration,
Cavitation,
Two-phase flow,
TurbulentFlow,
Volume of Fluid (VOF) method.

##### 10 Pressure Induced Isenthalpic Oscillations with Condensation and Evaporation in Saturated Two-Phase Fluids

**Authors:**
Joel V. Madison,
Hans E. Kimmel

**Abstract:**

**Keywords:**
condensation,
evaporation,
non-linear oscillations,
pressure induced,
two-phase flow