Modeling Bubble Collapse Aggressiveness in Traveling Bubble Cavitation using Bubble Breakup Model

2012 ◽  
Author(s):  
Patrik Zima ◽  
Milan Sedlář
Keyword(s):  
Bubble Collapse ◽  
Bubble Cavitation ◽  
Bubble Breakup ◽  
Breakup Model

An improved bubble breakup model in turbulent flow

2020 ◽  
Vol 386 ◽  
pp. 121484 ◽  
Author(s):  
Huahai Zhang ◽  
Guangyao Yang ◽  
Ali Sayyar ◽  
Tiefeng Wang
Keyword(s):  
Turbulent Flow ◽  
Bubble Breakup ◽  
Breakup Model

scholarly journals A CFD-PBM coupled model under entire turbulent spectrum for simulating a bubble column with highly viscous media

2021 ◽  
Author(s):  
Huahai Zhang ◽  
Yuelin Wang ◽  
Ali Sayyar ◽  
Tiefeng Wang
Keyword(s):  
Bubble Column ◽  
Coupled Model ◽  
Turbulent Energy ◽  
Balance Model ◽  
Inertial Subrange ◽  
Liquid Viscosity ◽  
Bubble Breakup ◽  
Turbulent Spectrum ◽  
Hydrodynamic Behaviors ◽  
Breakup Model

To account for the effect of liquid viscosity, the bubble breakup model considering turbulent eddy collision based on the inertial subrange turbulent spectrum was extended to the entire turbulent spectrum that included the energy-containing, inertial, and energy-dissipation subranges. The computational fluid dynamics-population balance model (CFD-PBM) coupled model was modified to include this extended bubble breakup model for simulations of a bubble column. The effect of turbulent energy spectrum on the bubble breakup and hydrodynamic behaviors was studied in a bubble column under different liquid viscosities. The results showed that when the liquid viscosity was < 80 mPas, the bubble breakup and hydrodynamics were almost independent on the turbulent spectrum. At liquid viscosity > 80 mPas, the bubble breakup rate and gas holdup were significantly under-predicted when the inertial turbulent spectrum was used, and when using the entire turbulent spectrum the predictions were more consistent with experimental data.

Numerical simulation of traveling bubble cavitation

2006 ◽  
Vol 16 (4) ◽  
pp. 393-416 ◽  
Author(s):  
Sunil Mathew ◽  
Theo G. Keith Theo G. Keith ◽  
Efstratios Nikolaidis
Keyword(s):  
Cavitation Bubble ◽  
Bubble Radius ◽  
Random Variable ◽  
Bubble Collapse ◽  
Maximum Pressure ◽  
Local Pressure ◽  
New Approach ◽  
Content Type ◽  
Collapse Pressure ◽  
Bubble Cavitation

PurposeThe purpose is to present a new approach for studying the phenomenon of traveling bubble cavitation.Design/methodology/approachA flow around a rigid, 2D hydrofoil (NACA‐0012) with a smooth surface is analyzed computationally. The Rayleigh‐Plesset equation is numerically integrated to simulate the growth and collapse of a cavitation bubble moving in a varying pressure field. The analysis is performed for both incompressible and compressible fluid cases. Considering the initial bubble radius as a uniformly distributed random variable, the probability density function of the maximum collapse pressure is determined.FindingsThe significance of the liquid compressibility during bubble collapse is illustrated. Furthermore, it is shown that the initial size of the bubble has a significant effect on the maximum pressure generated during the bubble collapse. The maximum local pressure developed during cavitation bubble collapse is of the order of 104 atm.Research limitations/implicationsA single bubble model that does not account for the effect of neighboring bubbles is used in this analysis. A spherical bubble is assumed.Originality/valueA new approach has been developed to simulate traveling bubble cavitation by interfacing a CFD solver for simulating a flow with a program simulating the growth and collapse of the bubble. Probabilistic analysis of the local pressure due to bubble collapse has been performed.

scholarly journals Observations of the dynamics and acoustics of travelling bubble cavitation

1991 ◽  
Vol 233 ◽  
pp. 633-660 ◽  
Author(s):  
S. L. Ceccio ◽  
C. E. Brennen
Keyword(s):  
Bubble Dynamics ◽  
Numerical Solutions ◽  
Maximum Size ◽  
Bubble Collapse ◽  
Size Distributions ◽  
Maximum Volume ◽  
Bubble Cavitation ◽  
Pressure Fields ◽  
Cavitation Nuclei ◽  
Event Rates

Individual travelling cavitation bubbles generated on two axisymmetric headforms were detected using a surface electrode probe. The growth and collapse of the bubbles were studied photographically, and these observations are related to the pressure fields and viscous flow patterns associated with each headform. Measurements of the acoustic impulse generated by the bubble collapse are analysed and found to correlate with the maximum volume of the bubble for each headform. These results are compared to the observed bubble dynamics and numerical solutions of the Rayleigh–Plesset equation. Finally, the cavitation nuclei flux was measured and predicted cavitation event rates and bubble maximum size distributions are compared with the measurements of these quantities.

An Investigation on the Bubble Breakup Characteristics by Recirculation Flow in a Venturi Channel

2021 ◽  
Author(s):  
Guodong Ding ◽  
Jiaqing Chen ◽  
Zhenlin Li
Keyword(s):  
Numerical Simulation ◽  
Flow Pattern ◽  
Slug Flow ◽  
Liquid Velocity ◽  
Bubble Collapse ◽  
Wall Region ◽  
Generation Process ◽  
Bubble Generation ◽  
Recirculation Flow ◽  
Bubble Breakup

Abstract Discrete bubbles can be effectively cracked and dispersed in a Venturi channel with its unique structural characteristics, and the general Venturi channel has been widely used in the practical engineering. Bubble breakup mechanisms based on Venturi channels have been extensively studied, but most of them are based on single bubble or bubble flow pattern. In this paper, the transport process of slug flow in a Venturi channel was explored through visualization experiments, and the characteristics of recirculation flow were indicated by numerical simulation method. The liquid velocity sensitively affects the bubble generation process. With the increase of the liquid velocity, the initial bubble is no longer detached from the gas injector hole, and the gas-liquid flow pattern changes from bubbly flow to slug flow. The slug bubble extends to the diverging section and experiences the process of interface instability, sub-bubble detachment and bubble collapse. The average Sauter bubble diameter decreases with the increase of liquid velocity, and the fitting function is Log Normal. There is a recirculation flow in the side wall region of the diverging section, and the area of the recirculation flow increases with the increase of the liquid velocity at the inlet. The numerical simulation results indicated that there is a large velocity gradient in the boundary region of the recirculation flow under slug flow pattern, which contribute to the bubble collapse.

Study on Bubble Breakup Mechanism in a Venturi Tube

2011 ◽  
Author(s):  
Yasumichi Nomura ◽  
Shin-ichiro Uesawa ◽  
Akiko Kaneko ◽  
Yutaka Abe
Keyword(s):  
Flow Structure ◽  
High Speed ◽  
Pressure Profile ◽  
Venturi Tube ◽  
Pressure Recovery ◽  
Bubble Collapse ◽  
Bubble Behavior ◽  
Low Velocity ◽  
Breakup Mechanism ◽  
Bubble Breakup

Microbubbles are expected to be applied in various subjects such as engineering and medical fields. Thus, on-demand microbubble generation techniques with high efficiently are required. In the present study, the microbubble generator using a venturi tube (converging-diverging nozzle) is focused. Although this technique realizes generation of many tiny bubbles with less than several-hundred-micrometer diameter, there are several unsolved parts of flow structure in a venturi tube on bubble breakup behavior. The purpose of this study is to clarify the bubble breakup mechanism in a venturi tube for practical use. In the present study, using a high speed camera for detailed observation of bubble behavior, the following features were obtained. In low velocity conditions, bubbles are divided in several pieces with a jet penetrating from the top (downstream) to the bottom (upstream) part of the bubble. In high velocity conditions, bubbles collapse in countless microbubbles with a drastic bubble expansion and shrinkage. Also, in order to clarify the flow structure in a venturi tube, pressure profile is measured in detail. Under chocking condition, the pressure profile shows the tendency of supersonic flow in a Laval nozzle and sudden pressure gradient appears in the diverging section. There are strong correlations between bubble fission points and pressure recovery points. It is suggested that bubble collapse is strongly influenced with pressure recovery in the diverging section.

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