Experiments on gravitational phase separation of binary immiscible fluids

2007 ◽  
Vol 591 ◽  
pp. 289-319 ◽  
Author(s):  
MISUZU SATO ◽  
IKURO SUMITA
Keyword(s):  
Phase Separation ◽  
Viscosity Ratio ◽  
Lower Boundary ◽  
Vertical Gradient ◽  
High Viscosity ◽  
Visual Observation ◽  
Immiscible Fluids ◽  
Water Mixture ◽  
Separation Rate ◽  
Two Phases

We conduct experiments on gravitational phase separation of binary immiscible fluids using an oil–water mixture and study how the volumetric and viscosity ratios of the two phases control the separation process. First, we change the volumetric fraction of the two phases. We find that the initial phase separation rate depends strongly on the volumetric ratio of the two phases, and can be modelled by a buoyancy-driven permeable flow using the Blake–Kozeny–Carman permeability formula. Next, we change the viscosity ratios of the two fluids, and we find that there are two distinct regimes with different styles of phase separation. Small viscosity ratio (<100) cases are characterized by a sharp lower boundary and a vertically homogeneous mixture layer. On the other hand, high viscosity ratio (>100) cases are characterized by a diffuse lower boundary and a large vertical gradient of porosity. A polyhedral foam structure develops at the top of the mixture layer which is slow to rupture and to transform into a uniform oil layer. These differences can be interpreted to arise from a faster coalescence rate relative to the separation rate at high viscosity ratios. We simultaneously measured electrical resistivity in order to monitor the temporal change of the mean porosity in the mixture layer. The measurements were found to be consistent with the visual observation.

Study of Fingering Dynamics of Two Immiscible Fluids in a Homogeneous Porous Medium with Considering Wettability Effects Using a Pore-Scale Multicomponent Lattice Boltzmann Model

2021 ◽  
Author(s):  
Eslam Ezzatneshan ◽  
Reza Goharimehr
Keyword(s):  
Porous Medium ◽  
Dynamic Viscosity ◽  
Lattice Boltzmann ◽  
Capillary Number ◽  
Viscosity Ratio ◽  
Viscous Fingering ◽  
Immiscible Fluids ◽  
Pore Scale ◽  
Homogeneous Porous Medium ◽  
Wetting Fluid

In the present study, a pore-scale multicomponent lattice Boltzmann method (LBM) is employed for the investigation of the immiscible-phase fluid displacement in a homogeneous porous medium. The viscous fingering and the stable displacement regimes of the invading fluid in the medium are quantified which is beneficial for predicting flow patterns in pore-scale structures, where an experimental study is extremely difficult. Herein, the Shan-Chen (S-C) model is incorporated with an appropriate collision model for computing the interparticle interaction between the immiscible fluids and the interfacial dynamics. Firstly, the computational technique is validated by a comparison of the present results obtained for different benchmark flow problems with those reported in the literature. Then, the penetration of an invading fluid into the porous medium is studied at different flow conditions. The effect of the capillary number (Ca), dynamic viscosity ratio (M), and the surface wettability defined by the contact angle (θ) are investigated on the flow regimes and characteristics. The obtained results show that for M<1, the viscous fingering regime appears by driving the invading fluid through the pore structures due to the viscous force and capillary force. However, by increasing the dynamic viscosity ratio and the capillary number, the invading fluid penetrates even in smaller pores and the stable displacement regime occurs. By the increment of the capillary number, the pressure difference between the two sides of the porous medium increases, so that the pressure drop Δp along with the domain at θ=40∘ is more than that of computed for θ=80∘. The present study shows that the value of wetting fluid saturation Sw at θ=40∘ is larger than its value computed with θ=80∘ that is due to the more tendency of the hydrophilic medium to absorb the wetting fluid at θ=40∘. Also, it is found that the magnitude of Sw computed for both the contact angles is decreased by the increment of the viscosity ratio from Log(M)=−1 to 1. The present study demonstrates that the S-C LBM is an efficient and accurate computational method to quantitatively estimate the flow characteristics and interfacial dynamics through the porous medium.

scholarly journals A CFD study on horizontal oil-water flow with high viscosity ratio

2021 ◽  
Vol 229 ◽  
pp. 116097
Author(s):  
Jing Shi ◽  
Mustapha Gourma ◽  
Hoi Yeung
Keyword(s):  
Water Flow ◽  
Viscosity Ratio ◽  
High Viscosity ◽  
Oil Water

scholarly journals Phase separation of multiphase droplets in a digital microfluidic device

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Mun Mun Nahar ◽  
Hyejin Moon
Keyword(s):  
Phase Separation ◽  
Capillary Number ◽  
Digital Microfluidics ◽  
Separation Performance ◽  
Comprehensive Investigation ◽  
Electrowetting On Dielectric ◽  
Splitting Technique ◽  
Droplet Splitting ◽  
Two Phases ◽  
Digital Microfluidic

Abstract This study reports the first comprehensive investigation of separation of the immiscible phases of multiphase droplets in digital microfluidics (DMF) platform. Electrowetting-on-dielectric (EWOD) actuation has been used to mechanically separate the phases. Phase separation performance in terms of percentage residue of one phase into another phase has been quantified. It was conceived that the residue formation can be controlled by controlling the deformation of the phases. The larger capillary number of the neck forming phase is associated with the larger amount of deformation as well as more residue. In this study, we propose two different ways to control the deformation of the phases. In the first method, we applied different EWOD operation voltages on two phases to maintain equal capillary numbers during phase separation. In the second method, while keeping the applied voltages same on both sides, we tested the phase separation performance by varying the actuation schemes. Less than 2% of residue was achieved by both methods, which is almost 90% improvement compared to the phase separation by the conventional droplet splitting technique in EWOD DMF platform, where the residue percentage can go up to 20%.

scholarly journals Phase Separation Behavior and System Properties of Aqueous Two-Phase Systems with Polyethylene Glycol and Different Salts: Experiment and Correlation

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Haihua Yuan ◽  
Yang Liu ◽  
Wanqian Wei ◽  
Yongjie Zhao
Keyword(s):  
Phase Separation ◽  
Sodium Citrate ◽  
Line Length ◽  
Continuous Phase ◽  
Two Phase ◽  
Separation Rate ◽  
Aqueous Two Phase Systems ◽  
Phase Systems ◽  
System Properties ◽  
Tie Line

The phase separation behaviors of PEG1000/sodium citrate, PEG4000/sodium citrate, PEG1000/ammonium sulfate, and PEG4000/ammonium sulfate aqueous two-phase systems were investigated, respectively. There are two distinct situations for the phase separation rate in the investigated aqueous two-phase systems: one state is top-continuous phase with slow phase separation rate and strong bottom-continuous phase with fast phase separation rate and weak volume ratio dependence. The system properties such as density, viscosity, and interfacial tension between top and bottom phases which have effects on the phase separation rate of aqueous two-phase systems were measured. The property parameter differences between the two phases increased with increasing tie line length and then improved the phase separation rate. Moreover, a modified correlation equation including the phase separation rate, tie line length, and physical properties of the four aqueous two-phase systems has been proposed and successfully tested in the bottom-continuous phase, whose coefficients were estimated through regression analysis. The predicted results of PEG1000/sodium citrate aqueous two-phase systems were verified through the stationary phase retention in the cross-axis countercurrent chromatography.

scholarly journals Buoyancy-driven flow in a confined aquifer with a vertical gradient of permeability

2018 ◽  
Vol 848 ◽  
pp. 411-429 ◽  
Author(s):  
Edward M. Hinton ◽  
Andrew W. Woods
Keyword(s):  
Rarefaction Wave ◽  
Pore Space ◽  
Lower Boundary ◽  
Leading Edge ◽  
Vertical Gradient ◽  
Vertical Shear ◽  
Classical Solutions ◽  
The Novel ◽  
Two Fluids ◽  
Gradient Of Permeability

We examine the injection of fluid of one viscosity and density into a horizontal permeable aquifer initially saturated with a second fluid of different viscosity and density. The novel feature of the analysis is that we allow the permeability to vary vertically across the aquifer. This leads to recognition that the interface may evolve as either a rarefaction wave that spreads at a rate proportional to $t$, a shock-like front of fixed length or a mixture of shock-like regions and rarefaction-wave-type regions. The classical solutions in which there is no viscosity ratio between the fluids and in which the formation has constant permeability lead to an interface that spreads laterally at a rate proportional to $t^{1/2}$. However, these solutions are unstable to cross-layer variations in the permeability owing to the vertical shear which develops in the flow, causing the structure of the interface to evolve to the rarefaction wave or shock-like structure. In the case that the viscosities of the two fluids are different, it is possible that the solution involves a mixture of shock-like and rarefaction-type structures as a function of the distance above the lower boundary. Using the theory of characteristics, we develop a regime diagram to delineate the different situations. We consider the implications of such heterogeneity for the prediction of front locations during $\text{CO}_{2}$ sequestration. If we neglect the permeability fluctuations, the model always predicts rarefaction-type solutions, while even modest changes in the permeability across a layer can introduce shocks. This difference may be very significant since it leads to the $\text{CO}_{2}$ plume occupying a greater fraction of the pore space between the injector and the leading edge of the $\text{CO}_{2}$ front in a layer of the same mean permeability. This has important implications for estimates of the fraction of the pore space that the $\text{CO}_{2}$ may access.

Theoretical Studies of Copper Oxide Clusters: Prediction of an Electronically Driven Phase Separation in YBa2Cu3Ox

1987 ◽  
Vol 99 ◽  
Author(s):  
L. A. Curtiss ◽  
T. O. Brun ◽  
D. M. Gruen
Keyword(s):  
Phase Diagram ◽  
Phase Separation ◽  
High Temperature ◽  
Copper Oxide ◽  
Superconducting Phase ◽  
Oxygen Stoichiometry ◽  
Molecular Orbital Calculations ◽  
Theoretical Studies ◽  
Two Phases ◽  
Semi Empirical

ABSTRACTOn the basis of semi-empirical extended Hiickel molecular orbital calculations of copper-oxide clusters representing the new superconducting material YBa2Cu3Ox, a phase diagram is proposed which suggests that the 94 K high temperature superconducting phase of YBa2Cu3Ox is characterized by an oxygen stoichiometry near 7.0. The phase diagram predicts that a plateau should exist for Tc in the region x = 0.0 – 0.25 and that in this region two phases are present which are characterized by compositions having oxygen stoichiometries 6.5–6.75 and ca. 7.0.

Unsteady transport of viscous incompressible semi-fluid mixtures in pipes

10.12737/6498 ◽  
2014 ◽  
Vol 9 (3) ◽  
pp. 72-77 ◽  
Author(s):  
Асадуллин ◽  
Nail Asadullin ◽  
Асадуллин ◽  
Linar Asadullin
Keyword(s):  
Work Experience ◽  
High Viscosity ◽  
Shear Stresses ◽  
Flow Cells ◽  
Design Elements ◽  
Fluid Mixtures ◽  
Reduce Energy Consumption ◽  
Reliable Design ◽  
Two Phases ◽  
Sanitary Conditions

Currently, a pressure method of transportation of semi mixtures in pipes is widespread. Work experience and research into the hydro-plants showed that this method of transportation is the most economical, is simple and highly reliable design elements, improve sanitary conditions and makes it possible to automate the process of transportation. One way to reduce energy consumption in transportation is the use of high-viscosity fluids transient driving modes - in particular the imposition of the vibration of a moving stream. Isotropic effects of vibration, consisting in the relative motion of a structured environment, leads to the destruction of bonds in the structure, reduce friction, the yield stress, which creates conditions of flow at low shear stresses. The article deals with the unsteady flow cells were obeying the law, which is quite accurately described by the Bingham-Shvedova. First, a simplified model of the motion-phase environment, based on the model adopted by a new one which took into account two phases of the transported medium. We received instantaneous velocity over the pipe section, which further enable us to obtain their average instantaneous value.

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