scholarly journals Numerical study of pressure loads generated by a shock-induced bubble collapse

2021 ◽  
Vol 33 (11) ◽  
pp. 113318
Author(s):  
Eric Goncalves da Silva ◽  
Philippe Parnaudeau
Keyword(s):  
Numerical Study ◽  
Bubble Collapse

Numerical study of the shock wave and pressure induced by single bubble collapse near planar solid wall

2021 ◽  
Vol 33 (7) ◽  
pp. 073311
Author(s):  
Xiaobin Yang ◽  
Cheng Liu ◽  
Decheng Wan ◽  
Changhong Hu
Keyword(s):  
Shock Wave ◽  
Numerical Study ◽  
Solid Wall ◽  
Single Bubble ◽  
Bubble Collapse

scholarly journals Numerical Study of the Collapse of Multiple Bubbles and the Energy Conversion during Bubble Collapse

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 247 ◽  
Author(s):  
Jing Zhang ◽  
Lingxin Zhang ◽  
Jian Deng
Keyword(s):  
Energy Conversion ◽  
Conversion Rate ◽  
Focal Point ◽  
Numerical Study ◽  
Solid Wall ◽  
Bubble Collapse ◽  
Liquid Interfaces ◽  
Acoustic Damping ◽  
Multiple Bubbles ◽  
Peak Value

This paper investigates numerically the collapses of both a single cavitation bubble and a cluster consisting of 8 bubbles, concerning mainly on the conversions between different forms of energy. Direct numerical simulation (DNS) with volume of fluid (VOF) method is applied, considering the detailed resolution of the vapor-liquid interfaces. First, for a single bubble near a solid wall, we find that the peak value of the wave energy, or equivalently the energy conversion rate decreases when the distance between the bubble and the wall is reduced. However, for the collapses of multiple bubbles, this relationship between the bubble-wall distance and the conversion rate reverses, implying a distinct physical mechanism. The evolutions of individual bubbles during the collapses of multiple bubbles are examined. We observe that when the bubbles are placed far away from the solid wall, the jetting flows induced by all bubbles point towards the cluster centre, while the focal point shifts towards the solid wall when the cluster is very close to the wall. We note that it is very challenging to consider thermal and acoustic damping mechanisms in the current numerical methods, which might be significant contributions to the energy budget, and we leave it open to the future studies.

scholarly journals An Experimental Approach to the Measurement of Wall Pressure Generated by an Underwater Spark-Generated Bubble by a Hopkinson Bar

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Xiongliang Yao ◽  
Xiongwei Cui ◽  
Kai Guo ◽  
Yingyu Chen
Keyword(s):  
Numerical Study ◽  
Underwater Explosion ◽  
Experimental System ◽  
Wall Pressure ◽  
Measuring System ◽  
Bubble Collapse ◽  
Pressure Loading ◽  
Hopkinson Pressure Bar ◽  
Sensing Element ◽  
Collapse Pressure

The wall pressure loading due to the underwater spark-generated bubble, having served as an efficient technique to study the underwater explosion, has drawn much attention. Compared with the numerical study of the pressure characteristics, the direct experimental investigation is much rarer. Recently, an improved pressure-measuring system by using a Hopkinson pressure bar as the sensing element is proposed, set up, and validated by the current authors. In this article, the improved methodology and experimental system is used to detect and analyze the pressure loading on the target plate surface due to the underwater spark-generated bubble beneath the plate. A series of experiments with 3 mm, 5 mm, 10 mm, 15 mm, …, 60 mm standoffs are carried out. The experimental results and the related analysis and discussions are presented. Based on the results, the improved methodology can be used to detect the pressure loading due to the spark-generated bubble. There is multipeak oscillation near the peak of the shock pressure loading profile. The peak pressure versus the standoff is also summarized. According to the characteristics of the induced water jet pressure and the bubble-collapse pressure loading given in this article, enough attention should be paid to not only the jet and the first bubble-collapse pressure loadings but also the secondary bubble-collapse pressure loadings especially when the dimensionless distance γ>1.

Experimental Study on Bubble Collapse Near a Solid Boundary

2016 ◽  
Author(s):  
Shuai Zhang ◽  
Shiping Wang ◽  
Yunlong Liu
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Bubble Radius ◽  
Water Layer ◽  
Lower Surface ◽  
Bubble Collapse ◽  
Solid Boundary ◽  
Liquid Jet ◽  
High Speed Photography ◽  
Generating Method

In this paper, we present a high-voltage electric-spark bubble-generating method which can generate a bubble with its maximum radius reaching up to ∼35 mm at a room pressure. Vertical migration and clear liquid jet inside the bubble are captured by a high speed photography. With this method, a series of experiments on bubbles collapse above a solid boundary are carried out under different non-dimensional standoff distances γ (= s/Rm, where s is the vertical distance from the bubble center to the solid boundary and Rm denotes the maximum bubble radius). It is found when bubble is extremely close to the solid boundary (γ < 0.6), the lower surface of the bubble will cling to the solid boundary, which causes the cone-shaped liquid jet to impact on solid boundary directly without buffering of the water layer. With the increase of γ, the bottom of the bubble is gradually away from the solid boundary with an increasing curvature, but the jet inside the bubble remains conical all along. The speed of the jet tip and the migration of the bubble top are also discussed subsequently, aiming to provide a reference for the numerical study. Finally, the critical value of γ is investigated, at which the effect of the buoyancy will compensate the attraction of the solid boundary when the buoyancy parameter of bubble is bout 0.06.

scholarly journals A Numerical and Experimental Study of Wall Pressure Caused by an Underwater Explosion Bubble

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Yingyu Chen ◽  
Xiongliang Yao ◽  
Xiongwei Cui
Keyword(s):  
High Speed ◽  
Bubble Dynamics ◽  
Numerical Study ◽  
Underwater Explosion ◽  
Rigid Wall ◽  
Numerical Results ◽  
Wall Pressure ◽  
Bubble Collapse ◽  
Strong Impact ◽  
Jet Impact

The bubble dynamics behaviors and the pressure in the wall center are investigated through experimental method and numerical study. In the experiment, the dynamics of an underwater explosion (UNDEX) bubble beneath a rigid wall are captured by high-speed camera and the wall pressure in the wall center is measured by pressure transducer. To reveal the process and mechanism of the pressure on a rigid wall during the first bubble collapse, numerical studies based on boundary element method (BIM) are applied. Numerical results with two different stand-off parameters (γ=0.38 and γ=0.90) show excellent agreement with experiment measurements and observations. According to the experimental and the numerical results, we can conclude that the first peak is caused by the reentrant jet impact and the following splashing effect enlarged the duration of the first jet impact. When γ=0.38, the splashing jet has a strong impact on the minimum volume bubble, a number of tiny bubbles, formed like bubble ring, are created and collapse more rapidly owing to the surrounding high pressure and emit multi shock waves. When γ=0.90, the pressure field around the bubble is low enough only a weak rebounding bubble peak occurs.

scholarly journals Bubble collapse near a solid boundary: a numerical study of the influence of viscosity

2002 ◽  
Vol 464 ◽  
pp. 137-163 ◽  
Author(s):  
STÉPHANE POPINET ◽  
STÉPHANE ZALESKI
Keyword(s):  
Reynolds Number ◽  
Impact Velocity ◽  
Critical Reynolds Number ◽  
Stokes Equations ◽  
Numerical Study ◽  
Scaling Law ◽  
Bubble Collapse ◽  
Solid Boundary ◽  
Surface Boundary ◽  
Jet Impact

The effect of viscosity on jet formation for bubbles collapsing near solid boundaries is studied numerically. A numerical technique is presented which allows the Navier–Stokes equations with free-surface boundary conditions to be solved accurately and efficiently. Good agreement is obtained between experimental data and numerical simulations for the collapse of large bubbles. However, the bubble rebound in our simulation is larger than that observed in laboratory experiments. This leads us to conclude that compressible and thermal effects should be taken into account to obtain a correct model of the rebound. A parametric study of the effect of viscosity on jet impact velocity is undertaken. The jet impact velocity is found to decrease as viscosity increases and above a certain threshold jet impact is impossible. We study how this critical Reynolds number depends on the initial radius and the initial distance from the wall. A simple scaling law is found to link this critical Reynolds number to the other non-dimensional parameters of the problem.

Numerical Study on Mass Transfer Effects on Spherical Cavitation Bubble Collapse in an Acoustic Field

2010 ◽  
Author(s):  
Ehsan Samiei ◽  
Mehrzad Shams ◽  
Reza Ebrahimi
Keyword(s):  
Mass Transfer ◽  
Cavitation Bubble ◽  
Bubble Dynamics ◽  
Numerical Study ◽  
Bubble Radius ◽  
Numerical Code ◽  
Bubble Collapse ◽  
Growth Time ◽  
Transfer Effects ◽  
Low Amplitude

A numerical code to simulate mass transfer effects on spherical cavitation bubble collapse in an acoustic pressure domain in quiescent water has been developed. Gilmore equation is used to simulate bubble dynamics, with considering mass diffusion and heat transfer. Bubbles with different initial radii were considered in quiescent infinite water in interaction with sinusoidal shock waves with different magnitudes of amplitude and frequency. Simulations were done in two cases; with and without considering mass transfer. Good agreement with reference data was achieved. For bubbles with small radii in high frequency pressure field with low amplitude, mass transfer causes larger maximum radii and growth time, and more violent resultant collapse. Decreasing pressure frequency or increasing its amplitude causes larger maximum radii, longer collapse time, and more violent collapse. But, in cases with mass transfer because at the last moments of collapse stage a large amount of water vapor is trapped inside the bubble, the collapse will become less violent. For larger bubbles collapse becomes more violent for the cases without mass transfer in all pressure amplitudes and higher frequencies. But decreasing pressure frequency makes the collapse of the bubbles with mass transfer more violent. However, mass transfer effects decreases with increasing initial bubble radius.

Numerical study of the low-frequency atomic dynamics in a Lennard-Jones glass

1998 ◽  
Vol 77 (2) ◽  
pp. 473-484 ◽  
Author(s):  
M. Sampoli, P. Benassi, R. Dell'Anna,
Keyword(s):  
Numerical Study ◽  
Low Frequency ◽  
Lennard Jones
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