Dynamics of Moving Gas Bubbles in Injection Cooling

1968 ◽  
Vol 90 (4) ◽  
pp. 371-378 ◽  
Author(s):  
N. Tokuda ◽  
W. J. Yang ◽  
J. A. Clark
Keyword(s):  
Bubble Dynamics ◽  
Perturbation Technique ◽  
Bubble Velocity ◽  
Time Interval ◽  
Bubble Motion ◽  
Bubble Behavior ◽  
Time Domains ◽  
Interfacial Temperature ◽  
Quiescent Liquid ◽  
Coordinate Perturbation

This paper presents a study of the growth or collapse of a spherical gas bubble being injected into a quiescent liquid of different compositions. The influence of translatory bubble velocity is given particular attention. Consideration is given to the case in which the bubble dynamics is governed by heat and mass transfer between the bubble and the liquid. By approximating the flow around the bubble as irrotational, two asymptotic solutions, valid for small and large times, respectively, are obtained for the thermal boundary layer over the bubble through the use of a coordinate perturbation technique. The bubble behavior in the two time domains is satisfactorily joined at a certain time interval. It is disclosed that the transient bubble size, interfacial temperature, and interfacial gas composition are governed by four dimensionless parameters. Translatory bubble motion is shown to cause a significant increase in the growth rate, an effect also provided by an increase in the Jakob number. Experimental results are cited and a favorable comparison with the theory is obtained.

Study on the Bubble Dynamics and the Exciting Force in a Bended Pipe Based on BEM

2016 ◽  
Author(s):  
Y. L. Liu ◽  
Z. L. Tian
Keyword(s):  
Numerical Model ◽  
Potential Theory ◽  
Bubble Dynamics ◽  
Flow Speed ◽  
Exciting Force ◽  
Incoming Flow ◽  
Bubble Motion ◽  
Dynamics Model ◽  
Pipe Surface ◽  
Direction Change

Nonlinear bubble dynamics in a pipeline and its exciting force are investigated by a numerical model based on BEM. The bubble motion is one of the main causes that the pipeline vibrates and generates noise in modern ships. The numerical bubble dynamics model is established under the incompressible potential theory. Bubble motion with different incoming flow in a bended pipe is simulated. We found that the bubble develops jet when it passes by the bend, and adjoin to the pipe surface in the side of the fillet center. The pulsation and the direction change of the bubble apply an exciting force on the pipe which has a positive correlation with the incoming flow speed and may lead vibration and noise.

Self-Propelled Sliding Bubble Motion Induced by Surface Microstructure in Pool Boiling of a Dielectric Fluid Under Microgravity

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Naveenan Thiagarajan ◽  
Sushil H. Bhavnani ◽  
Vinod Narayanan
Keyword(s):  
Vapor Bubble ◽  
Bubble Dynamics ◽  
Heated Surface ◽  
Pool Boiling ◽  
Bubble Nucleation ◽  
Radius Of Curvature ◽  
Dielectric Fluid ◽  
Bubble Motion ◽  
Reduced Gravity ◽  
Modification Technique

This paper reports bubble dynamics observed during pool boiling over microstructures with an asymmetric saw-tooth cross section, under reduced gravity. The periodic saw-toothed ratchets etched on a silicon surface include fabricated vapor bubble nucleation sites only on the shallow slope. Reduced gravity pool boiling experiments were conducted aboard a Boeing 727 aircraft carrying out parabolic maneuvers. The fluid used was FC-72, a highly wetting dielectric fluid used as a coolant for electronics. Under microgravity, it was observed that the bubble diameters were six times larger than in terrestrial gravity. Also, self-propelled sliding bubble motion along the surface of the saw teeth was observed in reduced gravity. The velocity of the sliding bubbles across the saw teeth, following lateral departure from the cavities, was measured to be as high as 27.4 mm/s. A model for the sliding bubble motion is proposed by attributing it to the force due to pressure differences that arise in the liquid film between the vapor bubble and the saw-toothed heated surface. The pressure difference is due to difference in the radius of curvature of the interface between the crest and trough of the saw teeth. The surface modification technique, which resulted in the sliding bubble motion, has the potential to alleviate dry-out caused due to stagnant vapor bubbles over heat sources under microgravity when the buoyancy forces are negligible compared to the surface tension forces.

Bubble Shape in Non-Newtonian Fluids

2002 ◽  
Vol 69 (5) ◽  
pp. 703-704 ◽  
Author(s):  
D. De Kee and ◽  
C. F. Chan Man Fong ◽  
J. Yao
Keyword(s):  
Newtonian Fluid ◽  
Bubble Dynamics ◽  
Complex Fluids ◽  
Newtonian Fluids ◽  
Bubble Velocity ◽  
Bubble Shape ◽  
Surfactant Effects

The study of the behavior of bubbles in complex fluids is of industrial as well as of academic importance. Bubble velocity-volume relations, bubble shapes, as well as viscous, elastic, and surfactant effects play a role in bubble dynamics. In this note we extend the analysis of Richardson to a non-Newtonian fluid.

Dynamics and Breakup Regime of a Vapor Bubble Traveling Through a Heated T-Shaped Branching Microchannel

2020 ◽  
Author(s):  
Zhe Yan ◽  
Shanshan Li ◽  
Lichun Li ◽  
Bili Deng ◽  
Zhenhai Pan
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Vapor Bubble ◽  
Bubble Dynamics ◽  
Surface Force ◽  
Bubble Motion ◽  
Heat Transfer Characteristics ◽  
Bubble Breakup ◽  
Wall Superheat ◽  
Frame Method

Abstract Dynamics and breakup characteristics of a vapor bubble when traveling through the T-junction of a heated branching microchannel are numerically investigated with the Volume of Fluid-Continuum-Surface-Force (VOF-CSF) method. The moving reference frame method, which has been demonstrated to help suppressing the unphysical spurious velocity around the liquid-vapor interface (Numer. Heat Trans. 67, 1–12), is employed and coupled to the VOF-CSF model. In order to evaluate the influence of the wall heating on the growth and breakup of vapor bubble, the saturated-interface-volume phase change model is further coupled to account for the phase change on the bubble interface. The numerical model is first validated against experimental results in literature. Then the effect of wall superheat on bubble dynamics and heat transfer coefficient is investigated. Bubble motion, growth, breakup and heat transfer characteristics at different wall superheats are analyzed in detail. Four bubble breakup regimes are observed, namely non-breakup (NB), breakup with tunnel (TB), combined breakup (CB) and breakup with permanent obstruction (OB). The present study reveals the transport details around an evaporating vapor bubble and helps understanding the underlying physics of bubble behaviors when traveling through a T-shaped branching microchannel.

Visualization of Micro-Scale Bubble Dynamics in Pure Liquids and Aqueous Surfactant Solutions

Volume 4 ◽  
2004 ◽  
Author(s):  
S. Sethu Raghavan ◽  
Raj M. Manglik
Keyword(s):  
Bubble Dynamics ◽  
Bubble Diameter ◽  
Dynamic Surface Tension ◽  
Bubble Surface ◽  
Dimethyl Formamide ◽  
Time Interval ◽  
Dynamic Surface ◽  
Micro Scale ◽  
Surfactant Solutions ◽  
Air Interface

Growth and departure of a single adiabatic bubble in pure liquids and aqueous surfactant solutions is visualized. High-resolution photographic records are obtained that characterize the micro-scale bubble dynamics (shape, size, and post-departure translation), the mean bubble diameter at different time periods of its growth and departure, and the bubble surface age (the time interval from the newly formed interface to the attainment of departure diameter). This pre- and post-departure dynamics of air bubbles is visualized in water, N, N dimethyl-formamide (DMF), and ethyl alcohol (all pure liquids), and aqueous surfactant solutions of SDS (1250 wppm, 2500 wppm, and 5000 wppm), CTAB (200 wppm), and Triton X-305 (1000 wppm). The evolution of different bubble shapes, sizes, and departure frequencies is presented to highlight the effects of surface-active forces. In the case of surfactant solutions, the dynamic effects of the molecular-scale adsorption-desorption dynamics of the additive at the liquid-air interface that manifests in the dynamic surface tension is also delineated.

scholarly journals Dynamics of Rising Bubbles in a Quiescent Slag Bath with Varying Thermo-Physical Properties

2020 ◽  
Vol 51 (6) ◽  
pp. 2843-2861
Author(s):  
D. Obiso ◽  
D. H. Schwitalla ◽  
I. Korobeinikov ◽  
B. Meyer ◽  
M. Reuter ◽  
...  
Keyword(s):  
Physical Properties ◽  
Bubble Dynamics ◽  
Fluid Dynamic ◽  
Temperature Gradients ◽  
Slag Bath ◽  
Bubble Motion ◽  
Temperature Dependent ◽  
Slag Properties ◽  
Temperature Dependent Properties ◽  
Thermo Physical Properties

AbstractThe motion of bubbles in a liquid slag bath with temperature gradients is investigated by means of 3D fluid dynamic computations. The goal of the work is to describe the dynamics of the rising bubbles, taking into account the temperature dependency of the thermo-physical properties of the slag. Attention is paid to the modeling approach used for the slag properties and how this affects the simulation of the bubble motion. In particular, the usage of constant values is compared to the usage of temperature-dependent data, taken from models available in the literature and from in-house experimental measurements. Although the present study focuses on temperature gradients, the consideration of varying thermo-physical properties is greatly relevant for the fluid dynamic modeling of reactive slag baths, since the same effect is given by heterogeneous species and solid fraction distributions. CFD is applied to evaluate the bubble dynamics in terms of the rising path, terminal bubble shape, and velocity, the gas–liquid interface area, and the appearance of break-up phenomena. It is shown that the presence of a thermal gradient strongly acts on the gas–liquid interaction when the temperature-dependent properties are considered. Furthermore, the use of literature models and experimental data produces different results, demonstrating the importance of correctly modeling the slag’s thermo-physical properties.

Coordinate perturbation and multiple scale in gasdynamics

1972 ◽  
Vol 272 (1222) ◽  
pp. 275-301 ◽  
Keyword(s):  
Flow Field ◽  
Perturbation Technique ◽  
Leading Edge ◽  
Multiple Scale ◽  
Initial Disturbance ◽  
Two Dimensional ◽  
Third Order ◽  
Closed Tube ◽  
Coordinate Perturbation

Usually, the application of the coordinate perturbation technique consists in transforming the equations to perturbed coordinates, and determining from the transformed equations the amount of coordinate straining appropriate to obtain a uniformly valid expansion. However, the transformed equations may become unwieldy with increasing order of the system, number of variables, and order of the approximation. There exists a much simpler way of applying the technique, which bypasses the transformed equations and provides the appropriate coordinate stretching by simple algebraic manipulations on the nonuniformly valid expansion obtained by straightforward expansion from the original equations. Interesting results are obtained by applying the procedure to two gasdynamical problems. In the first the flow field around a supersonic two-dimensional wing is determined up to third order, including a uniformly valid representation of the front shock shape, valid even when the shock does not start at the leading edge. The second problem concerns the oscillations in a closed tube following an arbitrary initial disturbance, both when the two ends are closed, and when one of the two ends contains an oscillating piston (the inviscid Chester problem). In both problems the uniformly valid expansions are substantially simpler than the non-uniformly valid. But most interesting is the result that the uniformly valid expansions cannot be obtained without supplementing the coordinate perturbation technique by the multiple scale technique.

Growth of gas bubbles in the biotissues with convective acceleration

2014 ◽  
Vol 07 (06) ◽  
pp. 1450072 ◽  
Author(s):  
S. A. Mohammadein ◽  
K. G. Mohamed
Keyword(s):  
Concentration Distribution ◽  
Bubble Dynamics ◽  
Ambient Pressure ◽  
Growth Stages ◽  
Gas Bubble ◽  
Bubble Motion ◽  
Dissolved Gas ◽  
Diffusion Limited ◽  
The Mathematical Model ◽  
Dominant Parameter

This paper presents formulae and explanation about the growth of a convective gas bubble in the blood and other tissues of divers who surface too quickly, concentration distribution around the growing bubble is also presented. The formulae are valid all over the growth stages, i.e. under variable ambient pressure while the diver is ascending, and under constant ambient pressure at diving stops or at sea level. The mathematical model is solved analytically by using the method of combined variables. The growth process is affected by tissue diffusivity, concentration constant and the initial void fraction, which is the dominant parameter. Results show that, the time of the complete growth, in the convective growth model, is shorter than those earlier presented by Mohammadein and Mohamed [Concentration distribution around a growing gas bubble in tissue, Math. Biosci.225(1) (2010) 11–17] and Srinivasan et al. [Mathematical models of diffusion-limited gas bubble dynamics in tissue, J. Appl. Physiol.86 (1999) 732–741] for the growth of a stationary gas bubble, this explains the effect of bubble motion on consuming the oversaturated dissolved gas from the tissue into growing bubble which leads to increment in the growth rate to be more than those presented in the previous stationary models.

scholarly journals Anodic Bubble Behavior in a Laboratory Scale Transparent Electrolytic Cell for Aluminum Electrolysis

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 806 ◽  
Author(s):  
Yipeng Huang ◽  
Zhaowen Wang ◽  
Youjian Yang ◽  
Bingliang Gao ◽  
Zhongning Shi ◽  
...  
Keyword(s):  
Bubble Dynamics ◽  
Aluminum Electrolysis ◽  
Electrolytic Cell ◽  
Laboratory Scale ◽  
Carbon Anode ◽  
Electrolysis Cell ◽  
Bubble Behavior ◽  
Electrolysis Process ◽  
Graphite Anodes ◽  
Carbon Anodes

In the Hall-Héroult process for extracting aluminum, the evolution and dynamics of anodic bubbles have a significant influence on the efficiency of the overall electrolysis process. In this study, the behavior of the bubbles beneath the carbon anode in cryolite-alumina molten salt was studied for the first time using a laboratory-scale transparent electrolysis cell to view the anode from the bottom. The bubble dynamics and the relevant characteristic parameters of bubbles were obtained using video cameras and image processing. It was found that the bubbles were observed to preferentially generate at several areas on the underside of the anode and the morphologies of coalesced bubbles show excellent similarity. Moreover, the behavior of gas on carbon and graphite anodes was significantly different, where the carbon anode favored the forming of larger bubbles. These observations confirmed different types of carbon anodes cause different bubble behavior. These findings are expected to be useful in optimizing the aluminum electrolysis process on an industrial scale.

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