Two-Phase Mixtures, Fluid Dispersions, and Liquid Films

2017 ◽  
pp. 96-134
Keyword(s):  
Liquid Films ◽  
Two Phase

scholarly journals Precise Determination of Liquid Layer Thickness with Downward Annular Two-Phase Gas-Very Viscous Liquid Flow

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6529
Author(s):  
Krystian Czernek ◽  
Stanisław Witczak
Keyword(s):  
Viscous Liquid ◽  
Liquid Layer ◽  
Liquid Flow ◽  
Liquid Films ◽  
Measuring System ◽  
Image Analysis System ◽  
Oil Viscosity ◽  
Two Phase ◽  
Study Results

The paper presents the characteristics of the original optoelectronic system for measuring the values of hydrodynamics of two-phase downward gas-very viscous liquid flow. The measurement methods and results of the research on selected values describing gas–oil two-phase flow are presented. The study was conducted in vertical pipes with diameters of 12.5, 16, 22, and 54 mm. The research was conducted with the superficial velocities of air jg = 0–29.9 m/s and oil jl = 0–0.254 m/s, which corresponded to the values of gas stream density gg = (0–37.31) kg/(m2s) and of liquid gl = (0.61–226.87) kg/(m2s), in order to determine the influence of air and oil streams on the character of liquid films. The variations in oil viscosity were applied in the range ηl = (0.055–1.517) Pas. The study results that were obtained with optical probes along with computer image analysis system revealed vast research opportunities in terms of the identification of gas–liquid two-phase downward flow structures that were generated as well as the determination of the thickness of liquid film with various level of interfacial surface area undulation. The designed and constructed proprietary measuring system is also useful for testing the liquid layer by determining the parameters of the resulting waves. It is considered that the apparatus system that is presented in the article is the most effective in examining the properties of liquid layers of oil and other liquids with low electrical conductivity and a significant degree of monochromatic light absorption. In view of noninvasive technique of measuring characteristic values of liquid films being formed, the above measuring system is believed to be very useful for industry in the diagnostics of the apparatus employing such flows.

A Two Dimensional Theory For Two Phase Detonation of Liquid Films

1971 ◽  
Vol 4 (1) ◽  
pp. 209-220 ◽  
Author(s):  
C. S. R. RAO ◽  
M. SICHEL ◽  
J. A. NICHOLLS
Keyword(s):  
Liquid Films ◽  
Two Dimensional ◽  
Dimensional Theory ◽  
Two Phase

Simulation of Copolymer Phase Separation in One-Dimensional Thin Liquid Films

2012 ◽  
Vol 2 (1) ◽  
pp. 33-46
Author(s):  
Hidenori Yasuda
Keyword(s):  
Phase Separation ◽  
Shallow Water Equations ◽  
Microphase Separation ◽  
Liquid Films ◽  
Thin Liquid Films ◽  
Two Phase ◽  
One Dimensional ◽  
Positive Volume ◽  
Spurious Oscillations ◽  
The One

AbstractThis paper discusses the development of an invariant finite difference scheme to simulate the microphase separation of copolymers in one-dimensional thin liquid films. The film phenomena are modelled using two-phase shallow water equations and the Ohta-Kawasaki potential, which governs the phase separation of the copolymer. Non-positive volume fractions and spurious oscillations are eventually eliminated, in simulating the one-dimensional phase separation lamellar pattern.

scholarly journals Two Reference Time Scales for Studying the Dynamic Cavitation of Liquid Films

1992 ◽  
Vol 114 (3) ◽  
pp. 612-615 ◽  
Author(s):  
D. C. Sun ◽  
D. E. Brewe
Keyword(s):  
Time Scales ◽  
Cavitation Bubble ◽  
Air Entrainment ◽  
Liquid Films ◽  
Dissolved Gas ◽  
Two Phase ◽  
Reference Time ◽  
Phase Fluid ◽  
Surrounding Liquid ◽  
Dissolved Air

Two formulas, one for the characteristic time of filling a void with the vapor of the surrounding liquid, and one of filling the void by diffusion of the dissolved gas in the liquid, are derived. By comparing these time scales with that of the dynamic operation of oil film bearings, it is concluded that the evaporation process is usually fast enough to fill the cavitation bubble with oil vapor; whereas the diffusion process is much too slow for the dissolved air to liberate itself and enter the cavitation bubble. These results imply that the formation of a two phase fluid in dynamically loaded bearings, as often reported in the literature, is caused by air entrainment. They further indicate a way to simplify the treatment of the dynamic problem of bubble evolution.

CFD Modeling of Two-Phase Gas-Liquid Slug Flow Using VOF Method in Microchannels

2009 ◽  
Author(s):  
A. Mehdizadeh ◽  
S. A. Sherif ◽  
W. E. Lear
Keyword(s):  
Numerical Simulation ◽  
Liquid Film ◽  
Slug Flow ◽  
Thin Liquid Film ◽  
Liquid Films ◽  
Vof Method ◽  
Cfd Modeling ◽  
Two Phase ◽  
Mesh Resolution ◽  
Gas Volume

Despite of the fact that numerical simulation of two-phase flows in microchannels has been attempted by many investigators, most efforts seem to have failed in correctly capturing the flow physics, especially the slug flow regime characteristics. The presence of a thin liquid film in the order of 10 μm around the bubble (sometimes called gas pocket or gas slug) may be a contributing factor to the above difficulty. Typically, liquid films have a significant effect on the flow field. Thus, there is a strong motivation to employ numerical simulation methods in order to avoid some of the experimental difficulties. In this paper, the characteristics of two-phase slug flows in microchannels are calculated with the help of the Volume-of-Fluid (VOF) method. Formation of the slugs for different superficial velocities, Capillary numbers, and gas volume fractions are investigated. The minimum mesh resolution required to capture the liquid film surrounding the gas bubble is reported employing a dynamic mesh adaption methodology with interface tracking. Results are shown to be in good agreement with experimental data and empirical correlations.

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