scholarly journals A note on the impulse due to a vapour bubble near a boundary

1982 ◽  
Vol 23 (4) ◽  
pp. 383-393 ◽  
Author(s):  
J. R. Blake ◽  
P. Cerone
Keyword(s):  
Free Surface ◽  
Point Source ◽  
Cavitation Bubble ◽  
High Speed ◽  
Liquid Jet ◽  
Vapour Bubble ◽  
Rigid Boundary ◽  
Two Fluids ◽  
Collapse Phase

AbstractAn expression for the impluse due to a vapour (cavitation) bubble is obtained in terms of an integral over a nearby boundary. Examples for a point source near a free surface, rigid boundary, inertial boundary and a fluid of different density are considered. It appears that the sign of the impluse determines the direction a cavitation bubble will migrate and the direction of the high speed liquid jet during the collapse phase. The theory may explain recent observations on buoyant bubbles near an interface between two fluids of different densities.

scholarly journals A note on the instantaneous streamlines, pathlines and pressure contours for a cavitation bubble near a boundary

1984 ◽  
Vol 26 (1) ◽  
pp. 31-44 ◽  
Author(s):  
P. Cerone ◽  
J. R. Blake
Keyword(s):  
Free Surface ◽  
Stagnation Point ◽  
Cavitation Bubble ◽  
Maximum Pressure ◽  
Rigid Boundary ◽  
Initial Distance ◽  
Bubble Pressure ◽  
Collapse Phase

AbstractInstantaneous streamlines, particle pathlines and pressure contours for a cavitation bubble in the vicinity of a free surface and near a rigid boundary are obtained. During the collapse phase of a bubble near a free surface, the streamlines show the existence of a stagnation point between the bubble and the free surface which occurs at a different location from the point of maximum pressure. This phenomenon exists when the initial distance of the bubble is sufficiently close to the free surface for the bubble and free surface to move in opposite directions during collapse of the bubble. Pressure calculations during the collapse of a cavitation bubble near a rigid boundary show that the maximum pressure is substantially larger than the equivalent Rayleigh bubble of the same volume.

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.

Investigation of a cavitation bubble between a rigid boundary and a free surface

2007 ◽  
Vol 102 (9) ◽  
pp. 094904 ◽  
Author(s):  
Peter Gregorčič ◽  
Rok Petkovšek ◽  
Janez Možina
Keyword(s):  
Free Surface ◽  
Cavitation Bubble ◽  
Rigid Boundary

Free-Surface Shear Layer Instabilities on a High-Speed Liquid Jet

2000 ◽  
Vol 37 (1) ◽  
pp. 74-88 ◽  
Author(s):  
Kazuhiro Itoh ◽  
Yoshiyuki Tsuji ◽  
Hideo Nakamura ◽  
Yutaka Kukita
Keyword(s):  
Free Surface ◽  
Shear Layer ◽  
High Speed ◽  
Liquid Jet ◽  
Surface Shear

The role of ‘splashing’ in the collapse of a laser-generated cavity near a rigid boundary

1999 ◽  
Vol 380 ◽  
pp. 339-361 ◽  
Author(s):  
R. P. TONG ◽  
W. P. SCHIFFERS ◽  
S. J. SHAW ◽  
J. R. BLAKE ◽  
D. C. EMMONY
Keyword(s):  
High Speed ◽  
Vital Role ◽  
Boundary Integral ◽  
Boundary Integral Method ◽  
Liquid Jet ◽  
Rigid Boundary ◽  
Jet Impact ◽  
Pressure Peak ◽  
Peak Pressures ◽  
The Impact

Vapour cavities in liquid flows have long been associated with cavitation damage to nearby solid surfaces and it is thought that the final stage of collapse, when a high- speed liquid jet threads the cavity, plays a vital role in this process. The present study investigates this aspect of the motion of laser-generated cavities in a quiescent liquid when the distance (or stand-off) of the point of inception from a rigid boundary is between 0.8 and 1.2 times the maximum radius of the cavity. Numerical simulations using a boundary integral method with an incompressible liquid impact model provide a framework for the interpretation of the experimental results. It is observed that, within the given interval of the stand-off parameter, the peak pressures measured on the boundary at the first collapse of a cavity attain a local minimum, while at the same time there is an increase in the duration of the pressure pulse. This contrasts with a monotonic increase in the peak pressures as the stand-off is reduced, when the cavity inception point is outside the stated interval. This phenomenon is shown to be due to a splash effect which follows the impact of the liquid jet. Three cases are chosen to typify the splash interaction with the free surface of the collapsing cavity: (i) surface reconnection around the liquid jet; (ii) splash impact at the base of the liquid jet; (iii) thin film splash. Hydrodynamic pressures generated following splash impact are found to be much greater than those produced by the jet impact. The combination of splash impact and the emission of shock waves, together with the subsequent re-expansion, drives the flow around the toroidal cavity producing a distinctive double pressure peak.

The formation of toroidal bubbles upon the collapse of transient cavities

1993 ◽  
Vol 251 ◽  
pp. 79-107 ◽  
Author(s):  
J. P. Best
Keyword(s):  
High Speed ◽  
Pressure Field ◽  
Boundary Integral ◽  
Liquid Jet ◽  
Rigid Boundary ◽  
Damage Mechanisms ◽  
Cavity Collapse ◽  
It Impacts ◽  
Toroidal Bubble ◽  
Flow Domain

A spectacular feature of transient cavity collapse in the neighbourhood of a rigid boundary is the formation of a high-speed liquid jet that threads the bubble and ultimately impacts upon the side of the bubble nearest to the boundary. The bubble then evolves into some toroidal form, the flow domain being doubly connected. In this work, the motion of the toroidal bubble is computed by connecting the jet tip to the side of the bubble upon which it impacts. This connection is via a cut introduced into the flow domain and across which the potential is discontinuous, the value of this discontinuity being equal to the circulation in the flow. A boundary integral algorithm is developed to account for this geometry and some example computations are presented. Consideration of the pressure field in the fluid has implications for possible damage mechanisms to structures due to nearby cavity collapse.

scholarly journals Interaction of cavitation bubbles with the interface of two immiscible fluids on multiple time scales

2021 ◽  
Vol 932 ◽  
Author(s):  
Rui Han ◽  
A-Man Zhang ◽  
Sichao Tan ◽  
Shuai Li
Keyword(s):  
Time Scales ◽  
Time Scale ◽  
Cavitation Bubble ◽  
High Speed ◽  
Bubble Dynamics ◽  
Immiscible Fluids ◽  
Multiple Time Scales ◽  
Liquid Jet ◽  
Short Time Scale ◽  
Multiple Time

We experimentally, numerically and theoretically investigate the nonlinear interaction between a cavitation bubble and the interface of two immiscible fluids (oil and water) on multiple time scales. The underwater electric discharge method is utilized to generate a cavitation bubble near or at the interface. Both the bubble dynamics on a short time scale and the interface evolution on a much longer time scale are recorded via high-speed photography. Two mechanisms are found to contribute to the fluid mixing in our system. First, when a bubble is initiated in the oil phase or at the interface, an inertia-dominated high-speed liquid jet generated from the collapsing bubble penetrates the water–oil interface, and consequently transports fine oil droplets into the water. The critical standoff parameter for jet penetration is found to be highly dependent on the density ratio of the two fluids. Furthermore, the pinch-off of an interface jet produced long after the bubble dynamics stage is reckoned as the second mechanism, carrying water droplets into the oil bulk. The dependence of the bubble jetting behaviours and interface jet dynamics on the governing parameters is systematically studied via experiments and boundary integral simulations. Particularly, we quantitatively demonstrate the respective roles of surface tension and viscosity in interface jet dynamics. As for a bubble initiated at the interface, an extended Rayleigh–Plesset model is proposed that well predicts the asymmetric dynamics of the bubble, which accounts for a faster contraction of the bubble top and a downward liquid 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.

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