Interfacial circulation due to surface-active agents in steady two-phase flows

1966 ◽  
Vol 24 (2) ◽  
pp. 293-306 ◽  
Author(s):  
D. B. R. Kenning ◽  
M. G. Cooper
Keyword(s):  
Open Channel ◽  
Tap Water ◽  
Surface Film ◽  
Active Material ◽  
Two Phase ◽  
Measured Velocity ◽  
Air Bubble ◽  
Surface Active Agents ◽  
Surface Active ◽  
Surface Active Material

Steady circulatory motions at the surface of tap-water flowing in an open channel and past a hemispherical air bubble on a channel wall are described and explained by the presence of a film of surface-active material. Boundary conditions for the liquid phase are derived by assuming that the surface film is insoluble and incompressible. Good agreement is obtained between the theoretical and measured velocity fields in the open-channel flow.

Paper 33: Hydrodynamics of Surface Films: Modelling Laws for Two-Phase Flows Containing Dilute Surfactant

1967 ◽  
Vol 182 (8) ◽  
pp. 320-329
Author(s):  
D. B. R. Kenning
Keyword(s):  
Open Channel ◽  
Adsorption Process ◽  
Active Material ◽  
Surface Adsorption ◽  
Open Channel Flow ◽  
Surface Films ◽  
Two Phase Flows ◽  
Two Phase ◽  
Surface Active ◽  
Surface Active Material

The presence of surface-active material may modify appreciably the flow patterns in two-phase flows. A frequently employed model for the surface adsorption process is used to derive similarity conditions for such flows. The limitations of this model are discussed in relation to the formation of surface films on open channel flow of water containing dilute surfactant.

The effects of surface films in damping eddies at a free surface of a turbulent liquid

1966 ◽  
Vol 290 (1423) ◽  
pp. 515-526 ◽  
Keyword(s):  
Mass Transfer ◽  
Liquid Surface ◽  
Active Material ◽  
Surface Films ◽  
Surface Renewal ◽  
Elastic Stresses ◽  
Hydrodynamic Behaviour ◽  
Surface Active Agents ◽  
Surface Active ◽  
Surface Active Material

Mass-transfer rates across a gas liquid surface into a turbulent liquid depend markedly on the hydrodynamic behaviour of the liquid immediately subjacent to the interface. Though turbulence is always somewhat damped at a free liquid surface, there may remain significant movements of liquid into the plane of a clean surface. A very small amount of surface-active material, however, sets up gradients of surface tension between different parts of the surface, and the accompanying (elastic) stresses are shown to damp very strongly eddies approaching the surface, thus reducing the rate of ‘surface renewal’: mass-transfer of a solute across the liquid surface is correspondingly retarded. This paper treats these phenomena quantitatively, and includes five predictions of the effects of surface-active agents. Comparison is made with published experimental data.

Surfactant inactivation by hyperventilation: conservation by end-expiratory pressure

1975 ◽  
Vol 38 (3) ◽  
pp. 461-466 ◽  
Author(s):  
I. Wyszogrodski ◽  
K. Kyei-Aboagye ◽  
H. W. Taeusch ◽  
M. E. Avery
Keyword(s):  
Surface Tension ◽  
Specific Activity ◽  
Surface Film ◽  
Active Material ◽  
Positive End Expiratory Pressure ◽  
Elastic Recoil ◽  
Minimum Surface Tension ◽  
Surface Active ◽  
Film Balance ◽  
Surface Active Material

Hyperventilation, defined as repeated hyperinflations, for three hours in open-chested anesthetized cats increased elastic recoil and elevated minimum surface tension of lung extracts as measured on a surface film balance. Equivalent hyperventilation from an elevated lung volume did not alter the pressure-volume relationships. When a mixture of [3H]glycerol and [14C]palmitate had been injected 17 h before the three hour period of phyerventilation, an increase in the ratio of specific activity in wash to tissue lecithin occurred in the hyperventilated cats compared to controls. These findings suggest that hyperventilation promotes release of surface active material from tissue to alveolus, but the released material is inactivated. The application of 2.5 cmH2O positive end-expiratory pressure prevented the adverse effects of hyperventilation. The same increase in wash to tissue lecithin occurred during this study; since the material was appropriately surface active, we conclude that the positive end-expiratory pressure prevented its inactivation.

Pulmonary surface film stability and composition

1979 ◽  
Vol 47 (3) ◽  
pp. 604-611 ◽  
Author(s):  
J. N. Hildebran ◽  
J. Goerke ◽  
J. A. Clements
Keyword(s):  
Surface Tension ◽  
Surface Film ◽  
Active Material ◽  
Lung Compliance ◽  
Indirect Measurements ◽  
Film Stability ◽  
Molar Ratios ◽  
Long Time ◽  
Surface Active ◽  
Surface Active Material

Stability of pulmonary alveoli at end expiration requires a very low air-water surface tension (e.g., less than 10 mN.m-1). Another important requirement is that the surface film maintain this low surface tension for a sufficiently long time at fixed lung volume. We measured monolayer collapse rates at 37 degrees C of lung surface-active material (SAM) and certain lipids found in this material and compared them with alveolar monolayer collapse rates calculated from published lung compliance changes. We found collapse rates for purified SAM or a mixture of dipalmitoyl lecithin (DPPC):monoenoic lecithin (PC):cholesterol (CHOL) (3.03:1.65:1 molar ratios) to be much greater than collapse rates of alveolar films estimated from indirect measurements. Monolayers of pure DPPC or DPPC with 10 mol% monoenoic PC and/or CHOL had collapse rates equal to or less than those estimated from lungs. We conclude that the alveolar monolayer is enriched in DPPC to the extent of 90 mol% or greater. Enrichment may exclude more mobile components from the monolayer during expiration when surface tension reaches verry low values.

Experimental Characterization of Slug Flow Velocity Distribution in Two Phase Pipe Flow

2009 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Peter Rodgers
Keyword(s):  
Velocity Distribution ◽  
Slug Flow ◽  
Two Phase ◽  
Significant Drop ◽  
Horizontal Pipe ◽  
Measured Velocity ◽  
Air Bubble ◽  
Velocity Magnitude ◽  
Index Matching ◽  
Refractive Index Matching

This paper presents an experimental study of gas-liquid slug flow inside a horizontal pipe. The influence of air bubble passage on liquid flow is characterized using Particle Image Velocimetry (PIV) combined with Refractive Index Matching (RIM) and fluorescent tracers. A physical insight into the velocity distribution within slug flow is presented. It was observed that the slug flow significantly influences the velocity profile in the liquid film. Measured velocity distributions also revealed a significant drop in the velocity magnitude immediately upstream of the slug nose. These findings aim to aid an understanding of the mechanism of solid transportation in slug flows.

Letter to the Editor

PEDIATRICS ◽  
1974 ◽  
Vol 54 (4) ◽  
pp. 519-519
Keyword(s):  
Amniotic Fluid ◽  
Active Material ◽  
Hyaline Membrane Disease ◽  
Clinical Entity ◽  
Letter To The Editor ◽  
Hyaline Membrane ◽  
Surface Active ◽  
Surface Active Material

Dr. Stevenson's observations concerning the association of amniotic fluid aspiration and hyaline membrane disease is quite interesting. Very little work, that we are aware of, has been done since these articles were published (1955 to 1958) to follow tip this theory. However, much work has been done to clarify the etiology of hyaline membrane disease. It is now well accepted that this clinical entity is directly related to the degree of immaturity of the lungs and the presence or absence of surface active material.

336. Surface activity and proteins of milk

1946 ◽  
Vol 14 (3) ◽  
pp. 316-329 ◽  
Author(s):  
R. Aschaffenburg
Keyword(s):  
Milk Fat ◽  
Chemical Nature ◽  
Active Material ◽  
Milk Proteins ◽  
Residual Fraction ◽  
Total Milk ◽  
Surface Active ◽  
Surface Active Material ◽  
Dilution Curves

As moderate dilution causes little change in the surface tension of milk, it is shown to be advantageous to use σ-dilution curves in place of the σ-values of the undiluted fluid as a characteristic of the surface properties of milk. The complications arising from the presence of the milk fat are described, and it is suggested that the influence of the fat is of a physical rather than of a chemical nature. A study of the role of the various milk proteins shows the casein to be of great importance, whilst the heat-coagulable proteins have little influence. The serum obtained after removal of the casein and heat-coagulable proteins contains a residual fraction of protein-like material which is markedly surface active though constituting only about 3% of the total milk proteins. The surface-active material (σ-proteose) has been concentrated and isolated, and its properties are described in some detail.

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