scholarly journals Dynamic Characteristics of Bubble Collapse Near the Liquid-Liquid Interface

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2794
Author(s):  
Zhaoqin Yin ◽  
Zemin Huang ◽  
Chengxu Tu ◽  
Xiaoyan Gao ◽  
Fubing Bao
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Liquid Droplet ◽  
Liquid Interface ◽  
Bubble Collapse ◽  
Dynamic Evolution ◽  
Liquid Jet ◽  
Bubble Generation ◽  
Generation Expansion ◽  
Different Shapes

Bubble collapse near the liquid-liquid interface was experimentally studied in this paper, and the dynamic evolution of a laser-induced bubble (generation, expansion, and collapse) and the liquid-liquid interface (dent and rebound) were captured by a high-speed shadowgraph system. The effect of the dimensionless distance between the bubble and the interface on the direction of the liquid jet, the direction of bubble migration, and the dynamics of bubble collapse were discussed. The results show that: (1) The jet generated during bubble collapse always directs toward the denser fluid; (2) bubble collapses penetrate the interface when the bubble is close to the interface; (3) three different shapes of the liquid-liquid interface—that is, a mushroom-shaped liquid column, a spike droplet, and a spherical liquid droplet—were observed.

scholarly journals Numerical and Experimental Study of the Interaction of a Spark-Generated Bubble and a Vertical Wall

2010 ◽  
Author(s):  
Arvind Jayaprakash ◽  
Georges Chahine ◽  
Chao-Tsung Hsiao
Keyword(s):  
Numerical Simulations ◽  
High Speed ◽  
Linear Time ◽  
Numerical Models ◽  
Vertical Wall ◽  
Bubble Collapse ◽  
Small Scale ◽  
Liquid Jet ◽  
Numerical Predictions ◽  
Jet Characteristics

An understanding of the fundamental mechanisms involved in the interaction between cavitation bubbles and structures is of importance for many applications involving cavitation erosion. Generally, the final stage of bubble collapse is associated with the formation of a high-speed reentrant liquid jet directed towards the solid surface. Local forces associated with the collapse of such bubbles can be very high and can exert significant loads on the materials. This formation and impact of liquid jet is an area of intense research. Under some conditions the presence of gravity and other nearby boundaries and free surfaces alters the jet direction and need to be understood, especially that in the laboratory, small scale tests in finite containers have these effects inherently present. In this work, experiments and numerical simulations of the interaction between a vertical wall and a bubble were carried out using Dynaflow’s three-dimensional code, 3DynaFS_Bem©, which models the unsteady dynamics of a liquid flow including the presence of highly non-linear time evolving gas-liquid interfaces. The numerical predictions were validated using scaled experiments carried out using spark generated bubbles. These spark bubble tests produced high fidelity test data that properly scale the fluid dynamics as long as the geometric non-dimensional parameters, gravity and time are properly scaled. The use of high speed cameras allowing framing rates as high as 50,000 frames per second to photograph the bubbles produced high quality observations of bubble dynamics including clear visualizations of reentrant jet formation inside the bubble. Such observations were very useful in developing and validating the numerical models. The cases studied showed very good correlation between the numerical simulations and the experimental observations and allowed development of predictive rules for the re-entrant jet characteristics, including jet angle and various definitions of the jet speed.

Dynamics of laser-induced cavitation bubbles near elastic boundaries: influence of the elastic modulus

2001 ◽  
Vol 433 ◽  
pp. 283-314 ◽  
Author(s):  
EMIL-ALEXANDRU BRUJAN ◽  
KESTER NAHEN ◽  
PETER SCHMIDT ◽  
ALFRED VOGEL
Keyword(s):  
Elastic Modulus ◽  
High Speed ◽  
Maximum Velocity ◽  
Biological Tissues ◽  
Bubble Collapse ◽  
Liquid Jet ◽  
High Speed Photography ◽  
Subsequent Formation ◽  
Elastic Boundary ◽  
Bubble Behaviour

The interaction of a laser-induced cavitation bubble with an elastic boundary is investigated experimentally by high-speed photography and acoustic measurements. The elastic material consists of a polyacrylamide (PAA) gel whose elastic properties can be controlled by modifying the water content of the sample. The elastic modulus, E, is varied between 0.017 MPa and 2.03 MPa, and the dimensionless bubble–boundary distance, γ, is for each value of E varied between γ = 0 and γ = 2.2. In this parameter space, jetting behaviour, jet velocity, bubble migration and bubble oscillation time are determined. The jetting behaviour varies between liquid jet formation towards or away from the elastic boundary, and formation of an annular jet which results in bubble splitting and the subsequent formation of two very fast axial liquid jets flowing in opposite directions. The liquid jet directed away from the boundary reaches a maximum velocity between 300 ms−1 and 600 ms−1 (depending on the elastic modulus of the sample) while the peak velocity of the jet directed towards the boundary ranges between 400 ms−1 and 800 ms−1 (velocity values averaged over 1 μs). Penetration of the elastic boundary by the liquid jet is observed for PAA samples with an intermediate elastic modulus between 0.12 and 0.4 MPa. In this same range of elastic moduli and for small γ-values, PAA material is ejected into the surrounding liquid due to the elastic rebound of the sample surface that was deformed during bubble expansion and forms a PAA jet upon rebound. For stiffer boundaries, the bubble behaviour is mainly characterized by the formation of an axial liquid jet and bubble migration directed towards the boundary, as if the bubble were adjacent to a rigid wall. For softer samples, the bubble behaviour becomes similar to that in a liquid with infinite extent. During bubble collapse, however, material is torn off the PAA sample when bubbles are produced close to the boundary. We conclude that liquid jet penetration into the boundary, jet-like ejection of boundary material, and tensile-stress-induced deformations of the boundary during bubble collapse are the major mechanisms responsible for cavitation erosion and for cavitation-enhanced ablation of elastic materials as, for example, biological tissues.

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 Numerical and Experimental Study of the Interaction of a Spark-Generated Bubble and a Vertical Wall

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Arvind Jayaprakash ◽  
Chao-Tsung Hsiao ◽  
Georges Chahine
Keyword(s):  
Numerical Simulations ◽  
High Speed ◽  
Numerical Models ◽  
Vertical Wall ◽  
Bubble Collapse ◽  
Small Scale ◽  
Liquid Jet ◽  
Numerical Predictions ◽  
Highly Nonlinear ◽  
Jet Characteristics

An understanding of the fundamental mechanisms involved in the interaction between bubbles and structures is of importance for many applications involving cavitation erosion. Generally, the final stage of bubble collapse is associated with the formation of a high-speed reentrant liquid jet directed toward the solid surface. Local forces associated with the collapse of such bubbles can be very high and can exert significant loads on the materials. This formation and impact of liquid jet is an area of intense research. Under some conditions, the presence of gravity and other nearby boundaries and free surfaces alters the jet direction and need to be understood, especially that in the laboratory, small scale tests in finite containers have these effects inherently present. In this work, experiments and numerical simulations of the interaction between a vertical wall and a bubble are carried out using Dynaflow’s three-dimensional code, 3DYNAFS-BEM, which models the unsteady dynamics of a liquid flow including the presence of highly nonlinear time evolving gas-liquid interfaces. The numerical predictions were validated using scaled experiments carried out using spark generated bubbles. These spark bubble tests produced high fidelity test data that properly scale the fluid dynamics as long as the geometric nondimensional parameters, gravity and time are properly scaled. The use of a high speed camera allowing framing rates as high as 50,000 frames per second to photograph the bubbles produced high quality observations of bubble dynamics including clear visualizations of the reentrant jet formation inside the bubble. Such observations were very useful in developing and validating the numerical models. The cases studied showed very good correlation between the numerical simulations and the experimental observations and allowed development of predictive rules for the re-entrant jet characteristics, including jet angle, jet speed, and various geometric characteristics of the jet.

PIV Measurements of Cavitation Bubble Collapse Flow Induced by Pressure Wave

2010 ◽  
Author(s):  
Sheng-Hsueh Yang ◽  
Shenq-Yuh Jaw ◽  
Keh-Chia Yeh
Keyword(s):  
Cavitation Bubble ◽  
High Speed ◽  
Bubble Radius ◽  
Ccd Camera ◽  
Bubble Surface ◽  
Bubble Collapse ◽  
Solid Boundary ◽  
Liquid Jet ◽  
Pressure Waves ◽  
Critical Position

In this study, a single cavitation bubble is generated by rotating a U-tube filled with water. A series of bubble collapse flows induced by pressure waves of different strengths are investigated by positioning the cavitation bubble at different stand-off distances to a solid boundary. Particle images of bubble collapse flow recorded by high speed CCD camera are analyzed by multi-grid, iterative particle image distortion method. Detail velocity variations of the transient bubble collapse flow are obtained. It is found that a Kelvin–Helmholtz vortex is formed when a liquid jet penetrates the bubble surface. If the bubble center to the solid boundary is within one to three times of the bubble radius, the liquid jet is able to impinge the solid boundary to form a stagnation ring. The fluid inside the stagnation ring will be squeezed toward the center of the ring to form a counter jet. At certain critical position, the bubble collapse flow will produce a Kelvin–Helmholtz vortex, the Richtmyer-Meshkov instability, or the generation of a counter jet flow, depending on the strengths of the pressure waves. If the bubble surface is in contact with the solid boundary, the liquid jet can only splash inside-out without producing the stagnation ring and the counter jet. The complex phenomenon of cavitation bubble collapse flows is clearly manifested in this study.

Pulsed jets driven by two interacting cavitation bubbles produced at different times

2017 ◽  
Vol 819 ◽  
pp. 465-493 ◽  
Author(s):  
Y. Tomita ◽  
K. Sato
Keyword(s):  
High Speed ◽  
Time Difference ◽  
Interaction Parameters ◽  
Bubble Collapse ◽  
High Speed Photography ◽  
Bubble Generation ◽  
Spray Formation ◽  
Cavitation Bubbles ◽  
Toroidal Bubble ◽  
Jet Impact

An experiment is performed using high-speed photography to elucidate the behaviours of jets formed by the interactions of two laser-induced tandem bubbles produced axisymmetrically for a range of dimensionless interaction parameters such as the bubble size ratio, $\unicode[STIX]{x1D709}$, the distance between the two cavitation bubbles, $l_{0}^{\ast }$, and the time difference in bubble generation, $\unicode[STIX]{x0394}\unicode[STIX]{x1D703}^{\ast }$. A strong interaction occurs for $l_{0}^{\ast }<1$. The first bubble produced (bubble A) deforms because of the rapid growth of the second bubble (bubble B) to create a pulsed conical jet, sometimes with spray formation at the tip, formed by the small amount of water confined between the two bubbles. This phenomenon is followed by bubble penetration, toroidal bubble collapse, and the subsequent fast contraction of bubble B accompanied by a fine jet. The formation mechanism of the conical jet is similar to that of a water spike developed in air from a deformed free surface of a single growing bubble; however, the pressures of the gases surrounding each type of jet differ. The jet behaviours can be controlled by manipulating the interaction parameters; the jet velocity is significantly affected by $\unicode[STIX]{x1D709}$ and $l_{0}^{\ast }$, but less so by $\unicode[STIX]{x0394}\unicode[STIX]{x1D703}^{\ast }$ for $\unicode[STIX]{x0394}\unicode[STIX]{x1D703}^{\ast }>\unicode[STIX]{x0394}\unicode[STIX]{x1D703}_{c}^{\ast }$ ($\unicode[STIX]{x0394}\unicode[STIX]{x1D703}_{c}^{\ast }$ being the critical birth-time difference). The optimum time of jet impact, at which bubble A reaches its maximum volume, depends on $\unicode[STIX]{x0394}\unicode[STIX]{x1D703}^{\ast }$. It is generally later for larger values of $\unicode[STIX]{x1D709}$. A pulsed jet could be used to create small pores in a cell membrane; therefore, the reported method may be useful for application in tandem-bubble sonoporation.

NONLINEAR SIMULATION OF A HIGH-SPEED, VISCOUS LIQUID JET

1998 ◽  
Vol 8 (2) ◽  
pp. 155-178 ◽  
Author(s):  
J. H. Hilbing ◽  
Stephen D. Heister
Keyword(s):  
Viscous Liquid ◽  
High Speed ◽  
Liquid Jet ◽  
Nonlinear Simulation

Dynamics of a bump of the gas-liquid interface on which a submerged liquid jet impinges

2002 ◽  
Author(s):  
Kunio Kataoka ◽  
Jianxing Zheng ◽  
Tokuo Yoshimura ◽  
Naoto Ohmura
Keyword(s):  
Liquid Interface ◽  
Liquid Jet

A modified damping model of vector form intrinsic finite element method for high-speed spiral bevel gear dynamic characteristics analysis

2021 ◽  
pp. 030932472110188
Author(s):  
Xiangying Hou ◽  
Yuzhe Zhang ◽  
Hong Zhang ◽  
Jian Zhang ◽  
Zhengminqing Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Numerical Solutions ◽  
Bevel Gear ◽  
Spiral Bevel Gear ◽  
Vector Form ◽  
Good Efficiency ◽  
Spiral Bevel ◽  
Damping Model

The vector form intrinsic finite element (VFIFE) method is springing up as a new numerical method in strong non-linear structural analysis for its good convergence, but has been constricted in static or transient analysis. To overwhelm its disadvantages, a new damping model was proposed: the value of damping force is proportional to relative velocity instead of absolute velocity, which could avoid inaccuracy in high-speed dynamic analysis. The accuracy and efficiency of the proposed method proved under low speed; dynamic characteristics and vibration rules have been verified under high speed. Simulation results showed that the modified VFIFE method could obtain numerical solutions with good efficiency and accuracy. Based on this modified method, high-speed vibration rules of spiral bevel gear pair under different loads have been concluded. The proposed method also provides a new way to solve high-speed rotor system dynamic problems.

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