Two-phase displacement in Hele-Shaw cells: experiments on viscously driven instabilities

1984 ◽  
Vol 141 ◽  
pp. 275-287 ◽  
Author(s):  
C.-W. Park ◽  
S. Gorell ◽  
G. M. Homsy
Keyword(s):  
Viscous Fluid ◽  
Contact Line ◽  
Growth Characteristics ◽  
Recent Theory ◽  
Two Phase ◽  
Quantitative Measurements ◽  
Viscous Oil ◽  
Static Contact ◽  
Growth Constants ◽  
Theory And Experiment

Experiments on the instability of the interface in two-phase displacements in Hele-Shaw cells were conducted using air and a viscous oil as the working fluids. The experiments had two objectives: (i) to provide quantitative measurements of the growth constants of the instability which occurs when a less-viscous fluid displaces a more-viscous one, and (ii) to compare the measured dispersion relations with the predictions of the recent theory of Park & Homsy (1984). The experiments were made by analysing the growth characteristics of between 10 and 20 Fourier modes describing the shape of the interface between displaced and displacing fluids, using still photography. For capillary numbers Ca = μU/γ less than approximately 4 × 10−3 the agreement is only fair, owing to substantial edge effects produced by a nearly static contact line near the lateral boundaries of the cell. For 4 × 10−3 < Ca < 1 × 10−2 theory and experiment agree to within the accuracy of the measurements. Location and verification of the behaviour of modes near the predicted cut-off wavenumber give partial verification of the theory of Park & Homsy.

Aeration in Lubrication With Application to Drag Torque Reduction

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Chinar R. Aphale ◽  
William W. Schultz ◽  
Steven L. Ceccio
Keyword(s):  
Contact Line ◽  
Neumann Boundary ◽  
Rotating Disk ◽  
Contact Angles ◽  
Standard Theory ◽  
Two Phase ◽  
Static Contact ◽  
Interface Contact ◽  
Dirichlet And Neumann Conditions

The aeration of an oil film flowing between the faces of two closely spaced circular plates (one stationary, and one rotating) is examined experimentally, numerically, and with an improved lubrication model. The gap between the plates is small compared to their radii, making lubrication theory appropriate for modeling the flow. However, standard lubrication boundary conditions suggested by Reynolds (1886, "On the Theory of Lubrication and its Application to Mr. Beauchamp Tower’s Experiments, Including an Experimental Determination of the Viscosity of Olive Oil," Philos. Trans. R. Soc. London, 177, pp. 157-234) of p = 0 and pn = 0 (Dirichlet and Neumann conditions on pressure) at the gas-liquid interface do not allow for the inclusion of a contact line model, a phenomenon that is important in the inception of aeration. Hence, the standard theory does not adequately predict the experimentally observed onset of aeration. In the present work, we modify the Neumann boundary condition to include both interfacial tension effects and the dynamics of the interface contact angle. The resulting one-dimensional Cartesian two-phase model is formulated to incorporate the prescribed contact line condition and tracks the interface shape and its motion. This model is then implemented in an axisymmetric, two-dimensional model of the rotating disk flow and used to predict the onset of aeration for varying surface tension and static contact angles. The results of the modified lubrication model are compared with experimental observations and with a numerical computation of the aerating flow using a volume of fluid method.

Analysis of Single- and Two-Phase Flows in Turbopump Inducers

1967 ◽  
Vol 89 (4) ◽  
pp. 577-586 ◽  
Author(s):  
P. Cooper
Keyword(s):  
Equation Of State ◽  
Flow Field ◽  
Thermal Effects ◽  
Single Phase ◽  
Fluid Pressure ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Recent Theory ◽  
Two Phase ◽  
Overall Efficiency

A model is developed for analytically determining pump inducer performance in both the single-phase and cavitating flow regimes. An equation of state for vaporizing flow is used in an approximate, three-dimensional analysis of the flow field. The method accounts for losses and yields internal distributions of fluid pressure, velocity, and density together with the resulting overall efficiency and pressure rise. The results of calculated performance of two sample inducers are presented. Comparison with recent theory for fluid thermal effects on suction head requirements is made with the aid of a resulting dimensionless vaporization parameter.

scholarly journals Moving contact line on chemically patterned surfaces

2008 ◽  
Vol 605 ◽  
pp. 59-78 ◽  
Author(s):  
XIAO-PING WANG ◽  
TIEZHENG QIAN ◽  
PING SHENG
Keyword(s):  
Contact Line ◽  
Critical Value ◽  
Diffuse Interface ◽  
Patterned Surfaces ◽  
Fluid Interface ◽  
Two Phase ◽  
Stick Slip ◽  
Moving Contact Line ◽  
Moving Contact ◽  
Wetting Fluid

We simulate the moving contact line in two-dimensional chemically patterned channels using a diffuse-interface model with the generalized Navier boundary condition. The motion of the fluid–fluid interface in confined immiscible two-phase flows is modulated by the chemical pattern on the top and bottom surfaces, leading to a stick–slip behaviour of the contact line. The extra dissipation induced by this oscillatory contact-line motion is significant and increases rapidly with the wettability contrast of the pattern. A critical value of the wettability contrast is identified above which the effect of diffusion becomes important, leading to the interesting behaviour of fluid–fluid interface breaking, with the transport of the non-wetting fluid being assisted and mediated by rapid diffusion through the wetting fluid. Near the critical value, the time-averaged extra dissipation scales as U, the displacement velocity. By decreasing the period of the pattern, we show the solid surface to be characterized by an effective contact angle whose value depends on the material characteristics and composition of the patterned surfaces.

scholarly journals Frictional Pressure Drop and Liquid Holdup of Churn Flow in Vertical Pipes with Different Viscosities

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zilong Liu ◽  
Yubin Su ◽  
Ming Lu ◽  
Zilong Zheng ◽  
Ruiquan Liao
Keyword(s):  
Pressure Drop ◽  
Liquid Velocity ◽  
Gas Velocity ◽  
Liquid Holdup ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Viscous Oil ◽  
Predicted Values ◽  
Superficial Gas Velocity ◽  
Churn Flow

Churn flow commonly exists in the pipe of heavy oil, and the characteristics of churn flow should be widely understood. In this paper, we carried out air and viscous oil two-phase flow experiments, and the diameter of the test section is 60 mm. The viscosity range of the oil was 100~480 mPa·s. Based on the measured liquid holdup and pressure drop data of churn flow, it can be concluded that, due to the existence of liquid film backflow, positive and negative frictional pressure drop can be found and the change of frictional pressure drop with the superficial gas velocity is related to superficial liquid velocity. With the increase of viscosity, the change rate of frictional pressure drop increases with the increase of the superficial gas velocity. Combining our previous work and the Taitel model, we proposed a new pressure drop model for viscous oil-air two-phase churn flow in vertical pipes. By comparing the predicted values of existing models with the measured pressure drop data, the proposed model has better performance in predicting the pressure drop.

scholarly journals ELECTROKINETIC PHENOMENA

1932 ◽  
Vol 16 (1) ◽  
pp. 1-3 ◽  
Author(s):  
Harold A. Abramson
Keyword(s):  
Electrophoretic Mobility ◽  
Crude Protein ◽  
Recent Theory ◽  
Protein Surfaces ◽  
Electrokinetic Phenomena ◽  
Theory And Experiment

As previously found experimentally for crude protein surfaces, and in harmony with recent theory and experiment, the ratio of the electroosmotic and electrophoretic mobility for surfaces of purified protein is approximately –1.00.

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