Numerical Simulation of Two-Phase Slug Flows in Microchannels

2009 ◽  
Author(s):  
A. Mehdizadeh ◽  
S. A. Sherif ◽  
W. E. Lear
Keyword(s):  
Surface Tension ◽  
Slug Flow ◽  
Stokes Equations ◽  
Pressure Fluctuations ◽  
Water Interface ◽  
Liquid Slug ◽  
Complex Flow ◽  
Two Phase ◽  
Air Water Interface ◽  
Slug Flows

In this paper the Navier-stokes equations for a single liquid slug have been solved in order to predict the circulation patterns within the slug. Surface tension effects on the air-water interface have been investigated by solving the Young–Laplace equation. The calculated interface shape has been utilized to define the liquid slug geometry at the front and tail interfaces of the slug. Then the effects of the surface tension on the hydrodynamics of the two-phase slug flow have been compared to those where no surface tension forces exist. The importance of the complex flow field features in the vicinity of the two interfaces has been investigated by defining a non-dimensional form of the wall shear stress. The latter quantity has been formulated based on non-dimensional parameters in order to define a general Moody friction factor for typical two-phase slug flows in microchannels. Moreover, the hydrodynamics of slug flow formation has been examined using computational fluid dynamics (CFD). The volume-of-fluid (VOF) method has been applied to monitor the growth of the instability at the air-water interface. The lengths of the slugs have been correlated to the pressure fluctuations in the mixing region of the air and water streams at an axisymmetric T-junction. The main frequencies of the pressure fluctuations have been investigated using the Fast Fourier Transform (FFT) method.

Surface Tension Effects on Liquid Flow in Small Plastic Tubes When Gas Bubbles are Present

2005 ◽  
Vol 219 (8) ◽  
pp. 853-857 ◽  
Author(s):  
M. R. Myers ◽  
H. M. Cave ◽  
S. P. Krumdieck
Keyword(s):  
Surface Tension ◽  
High Pressure ◽  
Pressure Drop ◽  
Liquid Flow ◽  
Slug Flow ◽  
Small Diameter ◽  
Gas Bubbles ◽  
Flow Regimes ◽  
Liquid Slug ◽  
Two Phase

Two-phase intermittent gas and liquid slug flow in small diameter glass and plastic tubes was studied. Two distinct flow regimes and the transition phenomena were identified. A modified Hagen-Poiseuille relation was derived to describe the extremely high pressure drop due to the surface tension effects of pinned slug flow.

Two-Phase Flow Induced Force Fluctuations on Pipe Bend

2014 ◽  
Author(s):  
Shuichiro Miwa ◽  
Yang Liu ◽  
Takashi Hibiki ◽  
Mamoru Ishii ◽  
Yoshiyuki Kondo ◽  
...  
Keyword(s):  
Flow Regime ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Pressure Fluctuations ◽  
Flow Regimes ◽  
Phase Flow ◽  
Liquid Slug ◽  
Two Phase ◽  
Pipe Bend ◽  
Force Fluctuation

In this study, fluctuating force induced by both upward and horizontal gas-liquid two-phase flow on 90 degree pipe bend at atmospheric condition was investigated. First, the database comprised of dynamic force signals and two-phase flow parameters such as volumetric fluxes, area averaged void fraction and pressure fluctuations covering entire two-phase flow regimes was developed for both flow orientations. Then, study was conducted to develop a model which is capable of predicting the force fluctuation frequency and magnitudes particularly for the slug flow regime. The model was fundamentally developed from the local instantaneous two-fluid model which was applied to the control volume around the elbow test section. Main contribution of the force fluctuation of two-phase flow is from the momentum and pressure fluctuations for most of the flow regimes. For slug flow regime, however, water-hammer like impact was produced by the collision of liquid slug against the structure surface. In order to consider that effect, the liquid slug impact force model was developed. The model utilizes two-group interfacial area concentration correlation to treat the flow regime transition without an abrupt discontinuity. It was found that the newly developed model is capable of predicting two-phase flow induced force fluctuation and dominant frequency range with satisfactory accuracy for flow regimes up to churn-turbulent.

Numerical Investigation on Flow Pattern and Pressure Drop Characteristics of Slug Flow in a Micro Tube

2008 ◽  
Author(s):  
Qunwe He ◽  
Nobuhide Kasagi
Keyword(s):  
Surface Tension ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Slug Flow ◽  
Thin Liquid Film ◽  
Surface Tension Force ◽  
Tension Force ◽  
Flow Profile ◽  
Liquid Slug ◽  
Two Phase

In the present study, numerical simulation of adiabatic air-water slug flow in a micro tube is carried out. The focus is laid upon the pressure drop characteristics and its modeling. The Phase-Field method is employed to capture the interface between the phases, while the surface tension force is represented by the chemical potential formulation. The numerical results agree fairly well with available experimental results in terms of bubble shape and flow pattern. Simulation is repeated under different conditions of pressure gradient, void fraction and bubble frequency. It is found that the total pressure drop of a slug flow can be decomposed into two parts, i.e., the frictional pressure drop associated with a liquid slug sandwiched by bubbles, and the pressure drop over a bubble itself. For the former, when the liquid slug is longer than one tube diameter, the cross-sectional velocity distribution resembles a Poiseuille flow profile, so that the corresponding pressure drop can be predicted by the theoretical solution of single-phase liquid flow, i.e., fReTP = 64. For the latter, if it is assumed that the surface tension force is strong enough to sustain a thin liquid film between the interface and the tube wall, the pressure drop in this region is negligible. The pressure drop over a bubble is solely dependent on the two-phase superficial Reynolds number ReTP, which can be correlated as: Δpbubb′ = 0.07 + 42.4 / ReTP. This correlation predicts well the two-phase pressure drop in the form of the two-phase multiplier correlation as a function of the Lockhart-Martinelli parameter.

scholarly journals Simulation Study on the Development Process and Phase Interface Structure of Gas-Liquid Slug Flow in a Horizontal Pipe

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiao Wu ◽  
Zhaoting Wang ◽  
Mei Dong ◽  
Quan Ge ◽  
Longfei Dong
Keyword(s):  
Velocity Field ◽  
Slug Flow ◽  
Development Process ◽  
Pressure Fluctuations ◽  
Phase Interface ◽  
Interface Structure ◽  
Liquid Slug ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Open Source Software Package

Here, a unified 3D numerical model of gas-liquid two-phase flow in a horizontal pipe was established using the interface capture method based on the open source software package OpenFOAM. Through numerical simulation of the natural slugging and development process of slug flow under different working conditions, the motion, phase interface structure, pressure and velocity field distributions of the liquid slug were fully developed and analyzed. The simulation results are consistent with the experiment. The results showed that during the movement of the slug head, there is a throwing phenomenon and a wave-like motion of the liquid slug. In addition, the slug tail and body area have very similar velocity profiles, and the overall velocity field distribution becomes more uniform with the development of liquid slug. Moreover, there are sudden pressure fluctuations at the head and tail of the liquid slug.

Analysis of Numerical Simulation of Gas-Liquid Slug Flow Using Slug Tracking Model

2015 ◽  
Author(s):  
Stella C. P. Cavalli ◽  
Cristiane Cozin ◽  
Fausto A. A. Barbuto ◽  
Rigoberto E. M. Morales
Keyword(s):  
Slug Flow ◽  
Oil And Gas ◽  
Initial Conditions ◽  
Computational Simulation ◽  
Flow Simulation ◽  
Gas Production ◽  
Liquid Slug ◽  
Two Phase ◽  
Tracking Model ◽  
Slug Flows

The distribution of the interfaces in gas-liquid two-phase flows in pipes can assume several shapes. Amongst those shapes, the slug flow pattern stands out as the most common one and occurs quite often in oil and gas production due to the flow rates and geometries used. This pattern is characterized by the succession of the so-called unit cells, that is, a flow structure composed of an aerated liquid slug and an elongated bubble surrounded by a liquid film. Due to its complexity, the study and understanding of this pattern’s behaviour becomes very important. The main methodologies used to describe slug flows are the steady-state one-dimensional models, based on the slug unit concept, and the transient approach, which takes the flow intermittence into account. The slug tracking model is one such transient approach, which considers slugs and elongated bubbles as separated bodies and analyzes the evolution along the flow and the interaction between those bodies. Whenever this model is numerically implemented, its initial conditions are important parameters that affect the results. The goal of this article is to study the influence of the initial conditions on slug flow simulation using the slug tracking model. A computer program written in Fortran95 using a slug tracking model to provide the characteristic parameters of slug flows such as the bubble and slug lengths and void fraction in the bubble region was built and used. The results were compared to experimental data and showed the important role the initial conditions play on the computational simulation of slug flow.

PRESSURE FLUCTUATIONS OF LIQUID-LIQUID SLUG FLOW IN CROSS-JUNCTION SQUARE MICROCHANNELS

2018 ◽  
Author(s):  
Jin-yuan Qian ◽  
Min-rui Chen ◽  
Zan Wu ◽  
Zhen Cao ◽  
Bengt Sunden
Keyword(s):  
Slug Flow ◽  
Pressure Fluctuations ◽  
Liquid Slug

From Surface Tension to Molecular Distribution: Modeling Surfactant Adsorption at the Air–Water Interface

Langmuir ◽  
2021 ◽  
Vol 37 (7) ◽  
pp. 2237-2255 ◽  
Author(s):  
Mengsu Peng ◽  
Timothy T. Duignan ◽  
Cuong V. Nguyen ◽  
Anh V. Nguyen
Keyword(s):  
Surface Tension ◽  
Surfactant Adsorption ◽  
Water Interface ◽  
Molecular Distribution ◽  
Distribution Modeling ◽  
Air Water Interface

Surface active properties at the air–water interface of β-casein and its fragments derived by plasmin proteolysis

1989 ◽  
Vol 56 (3) ◽  
pp. 487-494 ◽  
Author(s):  
Michael Wilson ◽  
Daniel M. Mulvihill ◽  
William J. Donnelly ◽  
Brian P. Gill
Keyword(s):  
Surface Tension ◽  
Water Interface ◽  
Active Protein ◽  
Drop Volume ◽  
V Protein ◽  
Proteose Peptone ◽  
Rate Determining Step ◽  
Surface Active Properties ◽  
Air Water Interface ◽  
Surface Active

Summaryβ-Casein, was enzymically modified by incubation with plasmin to yield γ-caseins and proteose peptones. Whole γ-, γ1-, γ2/γ3-caseins and whole proteose peptone (pp) were isolated from the hydrolysate mixture. The time dependence of surface tension at the air-water interface of solutions of β-casein and its plasmin derived fragments, at concentrations of 10−1 to 10−4% (w/v) protein, pH 7.0, was determined, at 25 °C, using a drop volume apparatus. The ranking of the proteins with respect to rate of reduction of surface tension, during the first rate determining step, at 10-2% (w/v) protein, was γ2/γ3 ≫ pp > whole γ- > γ1- > β-casein. The ranking of the proteins with respect to surface pressures attained after 40 min (π40) was concentration dependent. γ2/γ3-Caseins were found to be very surface active, decreasing surface tension rapidly and giving a high π40. γ1 Casein decreased surface activity somewhat faster than β-casein, but generally reached a lower π40. Whole γ-casein reflected the properties of both γ1 and γ2/γ3-caseins. Proteose peptone was found to decrease surface tension rapidly during the initial rate determining step; it gave a relatively high π40 at a bulk phase concentration of 10−3% (w/v) protein, but, it was the least surface active protein at 10−1 and 10−2% (w/v) protein.

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