Numerical simulation of bubble dynamics in central region of streamer

2018 ◽  
Vol 13 (3) ◽  
pp. 11-22 ◽  
Author(s):  
A.A. Aganin ◽  
A.I. Davletshin ◽  
T.F. Khalitova
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Central Region ◽  
Cavitation Bubble ◽  
High Speed ◽  
Hydrodynamic Interaction ◽  
Bubble Dynamics ◽  
Numerical Technique ◽  
Spherical Bubbles ◽  
Strong Expansion

A mathematical model and a numerical technique for studying strong expansion and collapse of cavitation bubbles located in the central region of a streamer where the bubbles are almost motionless are developed. They are essentially efficient combinations of the models and techniques previously created by the authors for calculating the dynamics of interacting weakly-non-spherical bubbles in a streamer and the dynamics of a single axisymmetric bubble. The first model and technique are applied at the low-speed stage of expansion and compression of bubbles where their hydrodynamic interaction is significant. The second ones are used at the final high-speed stage of their collapse where the interaction is inessential. The simplest case of the streamer comprising three bubbles is considered as an example to illustrate the features of the developed model and numerical technique. It is shown that under the strong expansion and collapse of an initially spherical cavitation bubble, the presence of neighboring bubbles can substantially deflect the bubble cavity vapor dynamics from what is realized inside a similar but single bubble.

scholarly journals Investigation and Numerical Simulation of a High-Current AC Circuit Breaker

2019 ◽  
Vol 6 (3) ◽  
pp. 235-238
Author(s):  
I. Murashov ◽  
V. Frolov ◽  
A. Kvashnin ◽  
J. Valenta ◽  
D. Simek ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
High Speed ◽  
Circuit Breaker ◽  
Moving Mesh ◽  
Electrical Characteristics ◽  
High Current ◽  
Spectral Diagnostics ◽  
Current Voltage ◽  
Time Calculation

The article is devoted to the study of the high-current AC circuit breaker. The results of the study are presented for various configurations of the arc divider. The study includes methods of spectral diagnostics and high-speed camera shooting synchronized with the electrical characteristics of the circuit breaker (current, voltage) in time. The obtained results allow to determine the composition of the plasma and dynamics of changes in the composition of the discharge in time. Calculation of the plasma composition and properties is made according to the obtained data, which makes it possible to take into account the products of circuit breaker materials ablation in numerical simulation. Non-stationary two-dimensional mathematical model with a moving mesh is developed. The obtained results allow to correct and verify the developed mathematical model of the circuit breaker operation. The evaluation of the arc divider influence is presented in the article.

Chromatically encoded high-speed photography of cavitation bubble dynamics inside inhomogeneous ophthalmic tissue

2016 ◽  
Author(s):  
N. Tinne ◽  
B. Matthias ◽  
F. Kranert ◽  
C. Wetzel ◽  
A. Krüger ◽  
...  
Keyword(s):  
Cavitation Bubble ◽  
High Speed ◽  
Bubble Dynamics ◽  
High Speed Photography

scholarly journals Cavitation and bubble dynamics: the Kelvin impulse and its applications

2015 ◽  
Vol 5 (5) ◽  
pp. 20150017 ◽  
Author(s):  
John R. Blake ◽  
David M. Leppinen ◽  
Qianxi Wang
Keyword(s):  
Cavitation Bubble ◽  
High Speed ◽  
Bubble Dynamics ◽  
Clinical Medicine ◽  
Bubble Collapse ◽  
Rigid Boundary ◽  
Design Problems ◽  
Practical Applications ◽  
Wide Range ◽  
Naval Engineering

Cavitation and bubble dynamics have a wide range of practical applications in a range of disciplines, including hydraulic, mechanical and naval engineering, oil exploration, clinical medicine and sonochemistry. However, this paper focuses on how a fundamental concept, the Kelvin impulse, can provide practical insights into engineering and industrial design problems. The pathway is provided through physical insight, idealized experiments and enhancing the accuracy and interpretation of the computation. In 1966, Benjamin and Ellis made a number of important statements relating to the use of the Kelvin impulse in cavitation and bubble dynamics, one of these being ‘One should always reason in terms of the Kelvin impulse, not in terms of the fluid momentum…’. We revisit part of this paper, developing the Kelvin impulse from first principles, using it, not only as a check on advanced computations (for which it was first used!), but also to provide greater physical insights into cavitation bubble dynamics near boundaries (rigid, potential free surface, two-fluid interface, flexible surface and axisymmetric stagnation point flow) and to provide predictions on different types of bubble collapse behaviour, later compared against experiments. The paper concludes with two recent studies involving (i) the direction of the jet formation in a cavitation bubble close to a rigid boundary in the presence of high-intensity ultrasound propagated parallel to the surface and (ii) the study of a ‘paradigm bubble model’ for the collapse of a translating spherical bubble, sometimes leading to a constant velocity high-speed jet, known as the Longuet-Higgins jet.

scholarly journals Numerical simulation of cavitation bubble dynamics induced by ultrasound waves in a high frequency reactor

2000 ◽  
Vol 7 (4) ◽  
pp. 217-227 ◽  
Author(s):  
G. Servant ◽  
J.P. Caltagirone ◽  
A. Gérard ◽  
J.L. Laborde ◽  
A. Hita
Keyword(s):  
Numerical Simulation ◽  
High Frequency ◽  
Cavitation Bubble ◽  
Bubble Dynamics ◽  
Ultrasound Waves

scholarly journals Microsecond resolution of cavitation bubble dynamics using a high-speed electrochemical impedance approach

2016 ◽  
Vol 52 (76) ◽  
pp. 11406-11409 ◽  
Author(s):  
P. R. Birkin ◽  
T. M. Foley ◽  
J. L. Barber ◽  
H. L. Martin
Keyword(s):  
Cavitation Bubble ◽  
High Speed ◽  
Bubble Dynamics ◽  
Electrochemical Impedance ◽  
New Method ◽  
Faradaic Current ◽  
Cavitation Action

A new method to detect changes in the uncompensated resistance, the capacitance and the Faradaic current at an electrode exposed to cavitation action is presented.

Cavitation bubble dynamics in a liquid gap of variable height

2011 ◽  
Vol 682 ◽  
pp. 241-260 ◽  
Author(s):  
SILVESTRE ROBERTO GONZALEZ-AVILA ◽  
EVERT KLASEBOER ◽  
BOO CHEONG KHOO ◽  
CLAUS-DIETER OHL
Keyword(s):  
Cavitation Bubble ◽  
High Speed ◽  
Strong Influence ◽  
Bubble Dynamics ◽  
Bubble Collapse ◽  
High Speed Photography ◽  
Expansion Time ◽  
Gap Height ◽  
Bubble Splitting ◽  
Narrow Gaps

We report on an experimental study of cavitation bubble dynamics within sub-millimetre-sized narrow gaps. The gap height is varied, while the position of the cavitation event is fixed with respect to the lower gap wall. Four different sizes of laser-induced cavitation bubbles are studied using high-speed photography of up to 430,000 frames per second. We find a strong influence of the gap height, H, on the bubble dynamics, in particular on the collapse scenario. Also, similar bubble dynamics was found for the same non-dimensional gap height η = H/Rx, where Rx is the maximum radius in the horizontal direction. Three scenarios are observed: neutral collapse at the gap centre, collapse onto the lower wall and collapse onto the upper wall. For intermediate gap height the bubble obtains a conical shape 1.4 < η < 7.0. For large distances, η > 7.0, the bubble no longer feels the presence of the upper wall and collapses hemispherically. The collapse time increases with respect to the expansion time for decreasing values of η. Due to the small scales involved, the final stage of the bubble collapse could not be resolved temporally and numerical simulations were performed to elucidate the details of the flow. The simulations demonstrate high-speed jetting towards the upper and lower walls and complex bubble splitting for neutral collapses.

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