scholarly journals The collapse of single bubbles and approximation of the far-field acoustic emissions for cavitation induced by shock wave lithotripsy

2011 ◽  
Vol 677 ◽  
pp. 305-341 ◽  
Author(s):  
A. R. JAMALUDDIN ◽  
G. J. BALL ◽  
C. K. TURANGAN ◽  
T. G. LEIGHTON
Keyword(s):  
Shock Wave ◽  
Shock Wave Lithotripsy ◽  
Near Field ◽  
Acoustic Emissions ◽  
Clinical Situation ◽  
Control Surface ◽  
Bubble Collapse ◽  
Far Field ◽  
Field Emissions ◽  
Computational Resources

Recent clinical trials have shown the efficacy of a passive acoustic device used during shock wave lithotripsy (SWL) treatment. The device uses the far-field acoustic emissions resulting from the interaction of the therapeutic shock waves with the tissue and kidney stone to diagnose the effectiveness of each shock in contributing to stone fragmentation. This paper details simulations that supported the development of that device by extending computational fluid dynamics (CFD) simulations of the flow and near-field pressures associated with shock-induced bubble collapse to allow estimation of those far-field acoustic emissions. This is a required stage in the development of the device, because current computational resources are not sufficient to simulate the far-field emissions to ranges of O(10 cm) using CFD. Similarly, they are insufficient to cover the duration of the entire cavitation event, and here simulate only the first part of the interaction of the bubble with the lithotripter shock wave in order to demonstrate the methods by which the far-field acoustic emissions resulting from the interaction can be estimated. A free-Lagrange method (FLM) is used to simulate the collapse of initially stable air bubbles in water as a result of their interaction with a planar lithotripter shock. To estimate the far-field acoustic emissions from the interaction, this paper developed two numerical codes using the Kirchhoff and Ffowcs William–Hawkings (FW-H) formulations. When coupled to the FLM code, they can be used to estimate the far-field acoustic emissions of cavitation events. The limitation of the technique is that it assumes that no significant nonlinear acoustic propagation occurs outside the control surface. Methods are outlined for ameliorating this problem if, as here, computational resources cannot compute the flow field to sufficient distance, although for the clinical situation discussed, this limitation is tempered by the effect of tissue absorption, which here is incorporated through the standard derating procedure. This approach allowed identification of the sources of, and explanation of trends seen in, the characteristics of the far-field emissions observed in clinic, to an extent that was sufficient for the development of this clinical device.

scholarly journals Prediction of far-field acoustic emissions from cavitation clouds during shock wave lithotripsy for development of a clinical device

2013 ◽  
Vol 469 (2150) ◽  
pp. 20120538 ◽  
Author(s):  
T. G. Leighton ◽  
C. K. Turangan ◽  
A. R. Jamaluddin ◽  
G. J. Ball ◽  
P. R. White
Keyword(s):  
Shock Wave ◽  
Kidney Stone ◽  
Shock Wave Lithotripsy ◽  
Acoustic Emissions ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Far Field ◽  
Pressure Fields ◽  
Bubble Interaction ◽  
Computational Resources

This study presents the key simulation and decision stage of a multi-disciplinary project to develop a hospital device for monitoring the effectiveness of kidney stone fragmentation by shock wave lithotripsy (SWL). The device analyses, in real time, the pressure fields detected by sensors placed on the patient's torso, fields generated by the interaction of the incident shock wave, cavitation, kidney stone and soft tissue. Earlier free-Lagrange simulations of those interactions were restricted (by limited computational resources) to computational domains within a few centimetres of the stone. Later studies estimated the far-field pressures generated when those interactions involved only single bubbles. This study extends the free-Lagrange method to quantify the bubble–bubble interaction as a function of their separation. This, in turn, allowed identification of the validity of using a model of non-interacting bubbles to obtain estimations of the far-field pressures from 1000 bubbles distributed within the focus of the SWL field. Up to this point in the multi-disciplinary project, the design of the clinical device had been led by the simulations. This study records the decision point when the project's direction had to be led by far more costly clinical trials instead of the relatively inexpensive simulations.

scholarly journals The Fluid-Solid Interaction Dynamics between Underwater Explosion Bubble and Corrugated Sandwich Plate

2016 ◽  
Vol 2016 ◽  
pp. 1-21
Author(s):  
Hao Wang ◽  
Yuan Sheng Cheng ◽  
Jun Liu ◽  
Lin Gan
Keyword(s):  
Shock Wave ◽  
Failure Modes ◽  
Sandwich Structures ◽  
Numerical Models ◽  
Near Field ◽  
Three Dimensional ◽  
Underwater Explosion ◽  
Bubble Collapse ◽  
Fe Model ◽  
Wave Load

Lightweight sandwich structures with highly porous 2D cores or 3D (three-dimensional) periodic cores can effectively withstand underwater explosion load. In most of the previous studies of sandwich structure antiblast dynamics, the underwater explosion (UNDEX) bubble phase was neglected. As the UNDEX bubble load is one of the severest damage sources that may lead to structure large plastic deformation and crevasses failure, the failure mechanisms of sandwich structures might not be accurate if only shock wave is considered. In this paper, detailed 3D finite element (FE) numerical models of UNDEX bubble-LCSP (lightweight corrugated sandwich plates) interaction are developed by using MSC.Dytran. Upon the validated FE model, the bubble shape, impact pressure, and fluid field velocities for different stand-off distances are studied. Based on numerical results, the failure modes of LCSP and the whole damage process are obtained. It is demonstrated that the UNDEX bubble collapse jet local load plays a more significant role than the UNDEX shock wave load especially in near-field underwater explosion.

Surface Integral Methods in Computational Aeroacoustics—From the (CFD) Near-Field to the (Acoustic) Far-Field

2003 ◽  
Vol 2 (2) ◽  
pp. 95-128 ◽  
Author(s):  
Anastasios S. Lyrintzis
Keyword(s):  
Near Field ◽  
Control Surface ◽  
Computational Aeroacoustics ◽  
Far Field ◽  
Acoustic Analogy ◽  
Surface Integral ◽  
Integral Methods ◽  
Field Noise ◽  
Cfd Method ◽  
Surface Integrals

A review of recent advances in the use of surface integral methods in Computational AeroAcoustics (CAA) for the extension of near-field CFD results to the acoustic far-field is given. These integral formulations (i.e. Kirchhoff's method, permeable (porous) surface Ffowcs-Williams Hawkings (FW-H) equation) allow the radiating sound to be evaluated based on quantities on an arbitrary control surface if the wave equation is assumed outside. Thus only surface integrals are needed for the calculation of the far-field sound, instead of the volume integrals required by the traditional acoustic analogy method (i.e. Lighthill, rigid body FW-H equation). A numerical CFD method is used for the evaluation of the flow-field solution in the near field and thus on the control surface. Diffusion and dispersion errors associated with wave propagation in the far-field are avoided. The surface integrals and the first derivatives needed can be easily evaluated from the near-field CFD data. Both methods can be extended in order to include refraction effects outside the control surface. The methods have been applied to helicopter noise, jet noise, propeller noise, ducted fan noise, etc. A simple set of portable Kirchhoff/FW-H subroutines can be developed to calculate the far-field noise from inputs supplied by any aerodynamic near/mid-field CFD code.

Influence of Pulse Repetition Rate on Cavitation at the Surface of an Object Targeted by Lithotripter Shock Waves

2007 ◽  
Author(s):  
Yuri A. Pishchalnikov ◽  
Mark M. Kaehr ◽  
James A. McAteer
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
Shock Wave Lithotripsy ◽  
Bubble Dynamics ◽  
Pulse Repetition Frequency ◽  
Pulse Repetition ◽  
Bubble Collapse ◽  
High Speed Imaging ◽  
Bubble Density ◽  
Induced Stresses

Stone breakage in shock wave lithotripsy is improved by slowing the rate of shock wave (SW) delivery. Previous studies have shown that increased cavitation at fast pulse repetition frequency (PRF) reduces the tensile phase of the SW, while the leading positive wave is virtually unaffected. Since the tensile component of the SW drives cavitation, and since cavitation at the stone contributes to breakage, it seems likely that increased cavitation along the path to the stone affects cavitation at the stone. Here we present preliminary data suggesting that PRF influences bubble dynamics at the stone. High-speed imaging showed that as PRF increased, bubble density of cavitation clouds increased, and the size of individual bubbles decreased. A new method to measure stresses generated by cavitation was used to show that locally induced stresses from bubble collapse can be greater than the incident SW, and were higher at 0.5Hz than at 2Hz PRF.

1264: Predictors of Shock-Wave Lithotripsy Success for Proximal Ureteral Calculi on Non-Contrast CT?

2007 ◽  
Vol 177 (4S) ◽  
pp. 417-417
Author(s):  
Eric A. Singer ◽  
Jared D. Christensen ◽  
Susan Messing ◽  
Erdal Erturk
Keyword(s):  
Shock Wave ◽  
Shock Wave Lithotripsy ◽  
Ureteral Calculi ◽  
Contrast Ct
Sign in / Sign up

Export Citation Format

Share Document