The Behavior of Gas Bubbles in the Casson Fluid

1978 ◽  
Vol 45 (1) ◽  
pp. 37-42 ◽  
Author(s):  
A. Shima ◽  
T. Tsujino
Keyword(s):  
Human Blood ◽  
Gas Bubbles ◽  
Equation Of Motion ◽  
Casson Fluid ◽  
Gas Bubble ◽  
Bubble Wall ◽  
Pressure Equation ◽  
The Difference

In the present paper, the equation of motion for the bubble and the pressure equation at the bubble wall in a Casson fluid were obtained. Then by using the derived equations, the behavior in the case where a gas bubble in human blood grows or collapses by the difference between the inside and the outside pressure of the bubble were numerically clarified.

The Behavior of Bubbles in Non-Newtonian Lubricants

1977 ◽  
Vol 99 (4) ◽  
pp. 455-461 ◽  
Author(s):  
A. Shima ◽  
T. Tsujino
Keyword(s):  
Rheological Properties ◽  
Bubble Radius ◽  
Equation Of Motion ◽  
Crude Oils ◽  
Bubble Wall ◽  
Pressure Equation ◽  
Cavitation Damage ◽  
Lubricating Oils ◽  
Cavitation Bubbles ◽  
Impulse Pressure

The behavior of cavitation bubbles and the impulse pressure occurring from the bubble in non-Newtonian lubricants are analyzed as one of the studies on cavitation which is caused on the bearing metals and oil pressure valves. That is, the equation of motion for a bubble and the pressure equation can be derived by using the Sisko model which well represents the rheological properties of lubricants (lubricating greases, and crude oils in place of lubricating oils), and the variation with time of the bubble radius and the pressure and velocity at the bubble wall in greases and crude oils are numerically obtained. In consequence, it was found that the impulse pressure occurring from the collapse of comparatively large bubbles can be a cause for the cavitation damage.

Gas bubble induced scalings in geothermal systems

2021 ◽  
Author(s):  
Lilly Zacherl ◽  
Thomas Baumann
Keyword(s):  
Ph Value ◽  
Saturation Index ◽  
Gas Bubbles ◽  
Gas Bubble ◽  
Geothermal Systems ◽  
Injection Wells ◽  
Term Operation ◽  
Maintenance Schedule ◽  
Local Experience ◽  
Maintenance Schedules

<p>Scalings in geothermal systems are affecting the efficiency and safety of geothermal systems. An operate-until-fail maintenance scheme might seem appropriate for subsurface installations where the replacement of pumps and production pipes is costly and regular maintenance comprises a complete overhaul of the installations. The situation is different for surface level installations and injection wells. Here, monitoring of the thickness of precipitates is the key to optimized maintenance schedules and long-term operation.</p><p>A questionnaire revealed that operators of geothermal facilities start with a standardized maintenance schedule which is adjusted based on local experience. Sensor networks, numerical modelling and predictive maintenance are not yet applied. In this project we are aiming to close this gap with the development of a non-invasive sensor system coupled to innovative data acquisition and evaluation and an expert system to quantitatively predict the development of precipitations in geothermal systems and open cooling towers.</p><p>Previous investigations of scalings in the lower part of production pipes of a geothermal facility suggest that the disruption of the carbonate equilibrium is triggered by the formation of gas bubbles in the pump and subsequent stripping of CO<sub>2</sub>. Although small in it's overall effect on pH-value and saturation index, significant amounts of precipitates are forming at high volumetric flow rates. To assess the kinetics of gas bubble induced precipitations laboratory experiments were run. The experiment addresses precipitations at surfaces and at the gas bubbles themselves.</p>

scholarly journals Physical controls on the storage of methane in landfast sea ice

2014 ◽  
Vol 8 (3) ◽  
pp. 1019-1029 ◽  
Author(s):  
J. Zhou ◽  
J.-L. Tison ◽  
G. Carnat ◽  
N.-X. Geilfus ◽  
B. Delille
Keyword(s):  
Sea Ice ◽  
Bubble Formation ◽  
Gas Bubble ◽  
Physical Processes ◽  
Ice Melt ◽  
Physical Controls ◽  
The Difference ◽  
Landfast Sea Ice ◽  
Ice Water ◽  
Brine Concentration

Abstract. We report on methane (CH4) dynamics in landfast sea ice, brine and under-ice seawater at Barrow in 2009. The CH4 concentrations in under-ice water ranged from 25.9 to 116.4 nmol L−1sw, indicating a supersaturation of 700 to 3100% relative to the atmosphere. In comparison, the CH4 concentrations in sea ice ranged from 3.4 to 17.2 nmol L−1ice and the deduced CH4 concentrations in brine from 13.2 to 677.7 nmol L−1brine. We investigated the processes underlying the difference in CH4 concentrations between sea ice, brine and under-ice water and suggest that biological controls on the storage of CH4 in ice were minor in comparison to the physical controls. Two physical processes regulated the storage of CH4 in our landfast ice samples: bubble formation within the ice and sea ice permeability. Gas bubble formation due to brine concentration and solubility decrease favoured the accumulation of CH4 in the ice at the beginning of ice growth. CH4 retention in sea ice was then twice as efficient as that of salt; this also explains the overall higher CH4 concentrations in brine than in the under-ice water. As sea ice thickened, gas bubble formation became less efficient, CH4 was then mainly trapped in the dissolved state. The increase of sea ice permeability during ice melt marked the end of CH4 storage.

Nuclei and Cavitation

1970 ◽  
Vol 92 (4) ◽  
pp. 681-688 ◽  
Author(s):  
J. William Holl
Keyword(s):  
Bubble Growth ◽  
Scale Effects ◽  
Gas Bubbles ◽  
Gas Content ◽  
Gas Bubble ◽  
Cavitation Nuclei ◽  
The Stability

This paper is a review of existing knowledge on cavitation nuclei. The lack of significant tensions in ordinary liquids is due to so-called weak spots or cavitation nuclei. The various forms which have been proposed for nuclei are gas bubbles, gas in a crevice, gas bubble with organic skin, and a hydrophobic solid. The stability argument leading to the postulation of the Harvey model is reviewed. Aspects of bubble growth are considered and it is shown that bubbles having different initial sizes will undergo vaporous cavitation at different liquid tensions. The three modes of growth, namely vaporous, pseudo, and gaseous are presented and implications concerning the interpretation of data are considered. The question of the source of nuclei and implications concerning scale effects are made. The measurement of nuclei is considered together with experiments on the effect of gas content on incipient cavitation.

Behavior of Inert Gas Bubbles in Forced Convective Liquid Metal Circuits

1976 ◽  
Vol 98 (1) ◽  
pp. 5-11 ◽  
Author(s):  
W. J. Minkowycz ◽  
D. M. France ◽  
R. M. Singer
Keyword(s):  
Liquid Metal ◽  
Bubble Dynamics ◽  
Bubble Radius ◽  
Gas Bubbles ◽  
Inert Gas ◽  
Liquid Sodium ◽  
Gas Bubble ◽  
Flowing Liquid ◽  
Argon Gas ◽  
The Core

Conservation equations are derived for the motion of a small inert gas bubble in a large flowing liquid-gas solution subjected to large thermal gradients. Terms which are of the second order of magnitude under less severe and steady-state conditions are retained, thus resulting in an expanded form of the Rayleigh equation. The bubble dynamics is a function of opposing mechanisms tending to increase or decrease bubble volume while being transported with the solution. Diffusion of inert gas between the bubble and the solution is one of the most important of these mechanisms included in the analysis. The analytical model is applied to an argon gas bubble flowing in a weak solution of argon gas in liquid sodium. Calculations are performed for these fluids under conditions typical of normal and abnormal operation of a liquid metal fast breeder reactor (LMFBR) core and the resulting bubble radius, internal gas pressure, and mass of inert gas are presented in each case. An important result obtained indicates that inert gas bubbles reaching the core inlet of an LMFBR will always grow as they traverse the core under normal and extreme abnormal conditions and that the rate of growth is quite small in all cases.

On the origin of the driving force in the Marangoni propelled gas bubble trapping mechanism

2017 ◽  
Vol 19 (28) ◽  
pp. 18695-18703 ◽  
Author(s):  
A. Miniewicz ◽  
C. Quintard ◽  
H. Orlikowska ◽  
S. Bartkiewicz
Keyword(s):  
Driving Force ◽  
Gas Bubbles ◽  
Gas Bubble ◽  
Particle Trajectories ◽  
Trapping Mechanism ◽  
Bubble Trapping

Particle trajectories around gas bubbles due to Marangoni induced flows of liquid.

Acoustic Properties of the Cod Swimbladder

1973 ◽  
Vol 58 (3) ◽  
pp. 797-820 ◽  
Author(s):  
OLAV SAND ◽  
A. D. HAWKINS
Keyword(s):  
Resonance Frequency ◽  
Relative Sensitivity ◽  
Acoustic Properties ◽  
Gas Bubble ◽  
A Value ◽  
Hearing Organ ◽  
Different Depths ◽  
Hearing Range ◽  
The Difference ◽  
Pressure Changes

1. The resonance frequency and damping of the swimbladder were measured for intact living cod at different depths. 2. At adaptation depth, the resonance frequency (fχ) of the organ was much higher than that predicted for an unrestrained gas bubble of similar volume. However, at much greater depths (where the hydrostatic pressure was 2 or more times greater than the adaptation pressure) fχ was only higher than expected by a factor of 1·25, and changed with depth in the manner of a free gas bubble. 3. The elevated values at greater depths can be explained in terms of the difference in shape between the swimbladder and an ideal spherical bubble, together with a clight effect from the surrounding tissues. We have calculated that the shear modulus of these tissues (µ1) has a value of approximately 1·7 x 106 dyne/cm2. However, we have suggested that the much higher elevation of fχ found at the adaptation depth results from a large increase in µ1 (by a factor of between 6 and 120). This increase may be the result of a maintained muscle tonus. 4. There is an immediate drop in fχ as a fish is moved to a new depth, but the elevated values are rapidly restored with time. This process of adjustment is too rapid to be accounted for by the restoration of the swimbladder to its former volume by the secretion or absorption of gas. It is possible that it is achieved by a muscular mechanism which restores µ1 to the former high value. 5. Though the maintenance of fχ at a high value may reflect mechanical processes concerned with the hydrostatic function of the swimbladder, or with the detection of static pressure changes, we suggest that it may also be of some value if the swimbladder is used as an accessory hearing organ. The maintenance of an fχ well above the hearing range of the fish ensures that the relative sensitivity of the animal to different frequencies does not alter with changes in depth.

Low Level Iodine Detection by TXRF in a Reactor Safety Simulation Experiment

1986 ◽  
Vol 30 ◽  
pp. 85-88 ◽  
Author(s):  
F. Hegedüs ◽  
P. Winkler ◽  
P. Wobrauschek ◽  
Christina Streli
Keyword(s):  
Simulation Experiment ◽  
Fission Products ◽  
Gas Bubbles ◽  
Vapor Concentration ◽  
Gas Bubble ◽  
Iodine Vapor ◽  
Reactor Safety ◽  
Water Pool ◽  
Federal Institute ◽  
Water Moderator

In the event of an accident in a light water moderated nuclear plant, the fission products escape from the water moderator in form of gas bubbles. One of the most important fission products is Iodine. Presently there are only rough estimations of the escape of Iodine. The aim of the experiment planned at the Swiss Federal Institute for Reactor Research (EIR) is to simulate the conditions of an accident and to measure the amount of Iodine which escapes from the moderator water into the space inside the reactor containment.It is supposed that at 5 m depth in a water pool, the canning of the fuel element explodes releasing 1-3 liter large gas bubbles containing the volatile fission products. The Iodine vapor concentration, saturated in the gas bubble, will be about 3 mg/l. It is expected that the water strongly absorbs the Iodine vapor and the I concentration in the gas bubble arriving at the water surface will be strongly reduced to a few ug/l.

scholarly journals Hydrodynamic interaction between gas bubbles in liquid

1976 ◽  
Vol 77 (1) ◽  
pp. 27-44 ◽  
Author(s):  
L. Van Wijngaarden ◽  
D. J. Jeffrey
Keyword(s):  
Relative Motion ◽  
Momentum Flux ◽  
Hydrodynamic Interaction ◽  
Liquid Mixture ◽  
Gas Bubbles ◽  
Gas Bubble ◽  
Virtual Mass ◽  
Bubble Liquid ◽  
The One

A calculation is given of the velocity which a cloud of identical gas bubbles acquires when the liquid in which the cloud is immersed is impulsively accelerated. From the results an expression follows for the effective virtual mass of a bubble in a gas-bubble/liquid mixture. Further consideration is given to that part of the momentum flux in the mixture associated with relative motion between liquid and bubbles. An expression for this quantity is derived which appears to differ from the one used in practice. It is shown that qualitative support for the expression obtained here is provided by experimental observations reported in the literature.

The velocity of rise of distorted gas bubbles in a liquid of small viscosity

1965 ◽  
Vol 23 (4) ◽  
pp. 749-766 ◽  
Author(s):  
D. W. Moore
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Gas Bubbles ◽  
Quantitative Agreement ◽  
Terminal Velocity ◽  
Dimensionless Group ◽  
Gas Bubble ◽  
Numerical Accuracy ◽  
Small Viscosity ◽  
Acceleration Of Gravity

The terminal velocity of rise of small, distorted gas bubbles in a liquid of small viscosity is calculated. Small viscosity means that the dimensionless group gμ4/ρT3 where g is the acceleration of gravity, μ the viscosity, ρ the density and T the surface tension, is less than 10−8. It is assumed—and the numerical accuracy of the assumption is discussed—that the distorted bubbles are oblate ellipsoids of revolution. The drag coefficient is found by extending the theory given recently (Moore 1963) for the boundary layer on a spherical gas bubble. The results are in reasonable quantitative agreement with the experimental data.

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