scholarly journals Gas depletion through single gas bubble diffusive growth and its effect on subsequent bubbles

2017 ◽  
Vol 831 ◽  
pp. 474-490 ◽  
Author(s):  
Álvaro Moreno Soto ◽  
Andrea Prosperetti ◽  
Detlef Lohse ◽  
Devaraj van der Meer
Keyword(s):  
Bubble Growth ◽  
Quantitative Data ◽  
Liquid Solution ◽  
Nucleation Site ◽  
Simplified Model ◽  
Gas Bubble ◽  
Dissolved Gas ◽  
Bubble Detachment ◽  
Diffusive Growth ◽  
Pure Diffusion

When a gas bubble grows by diffusion in a gas–liquid solution, it affects the distribution of gas in its surroundings. If the density of the solution is sensitive to the local amount of dissolved gas, there is the potential for the onset of natural convection, which will affect the bubble growth rate. The experimental study of the successive quasi-static growth of many bubbles from the same nucleation site described in this paper illustrates some consequences of this effect. The enhanced growth due to convection causes a local depletion of dissolved gas in the neighbourhood of each bubble beyond that due to pure diffusion. The quantitative data of sequential bubble growth provided in the paper show that the radius-versus-time curves of subsequent bubbles differ from each other due to this phenomenon. A simplified model accounting for the local depletion is able to collapse the experimental curves and to predict the progressively increasing bubble detachment times.

Understanding gas bubble trauma in an era of hydropower expansion: how do fish compensate at depth?

2020 ◽  
Vol 77 (3) ◽  
pp. 556-563 ◽  
Author(s):  
Naomi K. Pleizier ◽  
Charlotte Nelson ◽  
Steven J. Cooke ◽  
Colin J. Brauner
Keyword(s):  
Bubble Growth ◽  
Gas Bubble ◽  
Hydroelectric Dams ◽  
Dissolved Gas ◽  
Empirical Relationships ◽  
Lethal Effects ◽  
Exposed Fish ◽  
Total Dissolved Gas ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
The Relationship

Hydrostatic pressure is known to protect fish from damage by total dissolved gas (TDG) supersaturation, but empirical relationships are lacking. In this study we demonstrate the relationship between depth, TDG, and gas bubble trauma (GBT). Hydroelectric dams generate TDG supersaturation that causes bubble growth in the tissues of aquatic animals, resulting in sublethal and lethal effects. We exposed fish to 100%, 115%, 120%, and 130% TDG at 16 and 63 cm of depth and recorded time to 50% loss of equilibrium and sublethal symptoms. Our linear model of the log-transformed time to 50% LOE (R2 = 0.94) was improved by including depth. Based on our model, a depth of 47 cm compensated for the effects of 4.1% (±1.3% SE) TDG supersaturation. Our experiment reveals that once the surface threshold for GBT from TDG supersaturation is known, depth protects rainbow trout (Oncorhynchus mykiss) from GBT by 9.7% TDG supersaturation per metre depth. Our results can be used to estimate the impacts of TDG on fish downstream of dams and to develop improved guidelines for TDG.

The quasi-static growth of CO2 bubbles

2014 ◽  
Vol 741 ◽  
Author(s):  
Oscar R. Enríquez ◽  
Chao Sun ◽  
Detlef Lohse ◽  
Andrea Prosperetti ◽  
Devaraj van der Meer
Keyword(s):  
Boundary Layer ◽  
Growth Rate ◽  
Early Phase ◽  
Bubble Growth ◽  
Bubble Radius ◽  
Combined Effects ◽  
Gas Bubble ◽  
Final Phase ◽  
Concentration Boundary ◽  
Bubble Detachment

AbstractWe study experimentally the growth of an isolated gas bubble in a slightly supersaturated water–CO2 solution at 6 atm pressure. In contrast to what was found in previous experiments at higher supersaturation, the time evolution of the bubble radius differs noticeably from existing theoretical solutions. We trace the differences back to several combined effects of the concentration boundary layer around the bubble, which we disentangle in this work. In the early phase, the interaction with the surface on which the bubble grows slows down the process. In contrast, in the final phase, before bubble detachment, the growth rate is enhanced by the onset of density-driven convection. We also show that the bubble growth is affected by prior growth and detachment events, though they are up to 15 min apart.

Simplified Model for Prediction of Bubble Growth at Nucleation Site in Microchannels

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Sambhaji T. Kadam ◽  
Kuldeep Baghel ◽  
Ritunesh Kumar
Keyword(s):  
Vapor Phase ◽  
Waiting Time ◽  
Bubble Growth ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Nucleation Site ◽  
Simplified Model ◽  
Phase Flow ◽  
Two Phase ◽  
Proposed Model

Formation of the first bubble at nucleation site is an inception of the two phase flow in pool boiling and flow boiling. Bubble dynamics (bubble nucleation, growth, and departure) plays an important role in heat transfer and pressure drop characteristics during two phase flow in microchannels. In this paper, a simplified model has been developed for predicting bubble growth rate at nucleation cavity in microchannel. It is assumed that heat supplied at nucleation site is divided between the liquid phase and the vapor phase as per instantaneous void fraction value. The energy consumed by the vapor phase is utilized in bubble growth and overcoming resistive effects; surface tension, inertia, shear, gravity, and change in momentum due to evaporation. Proposed model shows a good agreement with available experimental works. In addition, the bubble waiting time phenomenon for flow boiling is also addressed using proposed model. Waiting time predicted by the model is also close to that obtained from experimental data.

The Effect of Shear Flow and Dissolved Gas Diffusion on the Cavitation in a Submerged Journal Bearing

2000 ◽  
Vol 123 (3) ◽  
pp. 494-500 ◽  
Author(s):  
M. Groper ◽  
I. Etsion
Keyword(s):  
Mass Transfer ◽  
Shear Flow ◽  
Mass Transport ◽  
Transport Mechanism ◽  
Journal Bearing ◽  
Gas Diffusion ◽  
Gas Bubble ◽  
Dissolved Gas ◽  
Rotating Shaft ◽  
Mass Transfer Mechanism

Two possible, long standing speculated mechanisms are theoretically investigated in an attempt to understand previous experimental observations of pressure build up in the cavitation zone of a submerged journal bearing. These mechanisms are (1) the shear of the cavity gas bubble by a thin lubricant film dragged through the cavitation zone by the rotating shaft and (2) the mass transfer mechanism which dictates the rate of diffusion of dissolved gas out of and back into the lubricant. A comparison with available experimental results reveals that while the cavitation shape is fairly well predicted by the “shear” mechanism, this mechanism is incapable of generating the level of the experimentally measured pressures, particularly towards the end of the cavitation zone. The “mass transport” mechanism is found inadequate to explain the experimental observations. The effect of this mechanism on the pressure build up in the cavitation zone can be completely ignored.

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.

Enhanced surface wettability and innate activity of an iron borate catalyst for efficient oxygen evolution and gas bubble detachment

2019 ◽  
Vol 7 (25) ◽  
pp. 15252-15261 ◽  
Author(s):  
Kamran Dastafkan ◽  
Yibing Li ◽  
Yachao Zeng ◽  
Li Han ◽  
Chuan Zhao
Keyword(s):  
Oxygen Evolution ◽  
Nickel Foam ◽  
Dip Coating ◽  
Surface Wettability ◽  
Gas Bubble ◽  
Iron Borate ◽  
Bubble Detachment ◽  
Enhanced Surface

Alternating dip-coating of iron borate on nickel foam provides surface wettability towards achieving a low-adhesion oxygen evolution electrode.

Acoustically Induced Gas Bubble Growth

1972 ◽  
Vol 51 (1B) ◽  
pp. 378-382 ◽  
Author(s):  
L. A. Skinner
Keyword(s):  
Bubble Growth ◽  
Gas Bubble
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