scholarly journals A Parametric Study of Bubble Cloud Dynamics near a Wall in an Acoustic Field

2018 ◽  
pp. 23-26
Keyword(s):  
Acoustic Field ◽  
Parametric Study ◽  
Bubble Cloud ◽  
Cloud Dynamics

scholarly journals Cavitation Bubble Cloud Break-Off Mechanisms at Micro-Channels

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 215
Author(s):  
Paul McGinn ◽  
Daniel Pearce ◽  
Yannis Hardalupas ◽  
Alex Taylor ◽  
Konstantina Vogiatzaki
Keyword(s):  
Cavitation Bubble ◽  
Cavitation Inception ◽  
Wave Dynamics ◽  
Bubble Cloud ◽  
Cloud Dynamics ◽  
Micro Channels ◽  
Physical Insight ◽  
Cloud Process ◽  
Good Agreement

This paper provides new physical insight into the coupling between flow dynamics and cavitation bubble cloud behaviour at conditions relevant to both cavitation inception and the more complex phenomenon of flow “choking” using a multiphase compressible framework. Understanding the cavitation bubble cloud process and the parameters that determine its break-off frequency is important for control of phenomena such as structure vibration and erosion. Initially, the role of the pressure waves in the flow development is investigated. We highlight the differences between “physical” and “artificial” numerical waves by comparing cases with different boundary and differencing schemes. We analyse in detail the prediction of the coupling of flow and cavitation dynamics in a micro-channel 20 m high containing Diesel at pressure differences 7 MPa and 8.5 MPa, corresponding to cavitation inception and "choking" conditions respectively. The results have a very good agreement with experimental data and demonstrate that pressure wave dynamics, rather than the “re-entrant jet dynamics” suggested by previous studies, determine the characteristics of the bubble cloud dynamics under “choking” conditions.

Collective oscillations in bubble clouds

2011 ◽  
Vol 680 ◽  
pp. 114-149 ◽  
Author(s):  
ZORANA ZERAVCIC ◽  
DETLEF LOHSE ◽  
WIM VAN SAARLOOS
Keyword(s):  
Frequency Response ◽  
Acoustic Field ◽  
Low Frequency ◽  
Acoustic Energy ◽  
Viscous Damping ◽  
Edge States ◽  
Bubble Cloud ◽  
Collective Oscillations ◽  
The Individual ◽  
Bubble Oscillations

In this paper the collective oscillations of a bubble cloud in an acoustic field are theoretically analysed with concepts and techniques of condensed matter physics. More specifically, we will calculate the eigenmodes and their excitabilities, eigenfrequencies, densities of states, responses, absorption and participation ratios to better understand the collective dynamics of coupled bubbles and address the question of possible localization of acoustic energy in the bubble cloud. The radial oscillations of the individual bubbles in the acoustic field are described by coupled linearized Rayleigh–Plesset equations. We explore the effects of viscous damping, distance between bubbles, polydispersity, geometric disorder, size of the bubbles and size of the cloud. For large enough clusters, the collective response is often very different from that of a typical mode, as the frequency response of each mode is sufficiently wide that many modes are excited when the cloud is driven by ultrasound. The reason is the strong effect of viscosity on the collective mode response, which is surprising, as viscous damping effects are small for single-bubble oscillations in water. Localization of acoustic energy is only found in the case of substantial bubble size polydispersity or geometric disorder. The lack of localization for a weak disorder is traced back to the long-range 1/r interaction potential between the individual bubbles. The results of the present paper are connected to recent experimental observations of collective bubble oscillations in a two-dimensional bubble cloud, where pronounced edge states and a pronounced low-frequency response had been observed, both consistent with the present theoretical findings. Finally, an outlook to future possible experiments is given.

Shock‐controlled bubble cloud dynamics and light emission.

2011 ◽  
Vol 129 (4) ◽  
pp. 2619-2619 ◽  
Author(s):  
R. Glynn Holt ◽  
Phillip A. Anderson ◽  
Ashwinkumar Sampathkumar ◽  
Jonathan R. Sukovich ◽  
D. Felipe Gaitan
Keyword(s):  
Light Emission ◽  
Bubble Cloud ◽  
Cloud Dynamics

scholarly journals Modeling and numerical simulation of the bubble cloud dynamics in an ultrasound field for burst wave lithotripsy

2018 ◽  
Vol 144 (3) ◽  
pp. 1780-1780
Author(s):  
Kazuki Maeda ◽  
Tim Colonius ◽  
Adam D. Maxwell ◽  
Wayne Kreider ◽  
Michael R. Bailey
Keyword(s):  
Numerical Simulation ◽  
Bubble Cloud ◽  
Ultrasound Field ◽  
Cloud Dynamics

scholarly journals Effects of acoustic parameters on bubble cloud dynamics in ultrasound tissue erosion (histotripsy)

2007 ◽  
Vol 122 (1) ◽  
pp. 229-236 ◽  
Author(s):  
Zhen Xu ◽  
Timothy L. Hall ◽  
J. Brian Fowlkes ◽  
Charles A. Cain
Keyword(s):  
Acoustic Parameters ◽  
Bubble Cloud ◽  
Cloud Dynamics

scholarly journals Numerical Investigation of Bubble Cloud Dynamics in Shock Wave Lithotripsy

2002 ◽  
Author(s):  
Michel Tanguay ◽  
Tim Colonius
Keyword(s):  
Shock Wave ◽  
Shock Wave Lithotripsy ◽  
Focal Point ◽  
Free Field ◽  
Single Pulse ◽  
Curvilinear Coordinates ◽  
Artificial Kidney ◽  
Bubble Cloud ◽  
Extracorporeal Shock Wave ◽  
Cloud Dynamics

To provide greater understanding of some of the phenomena in Extracorporeal Shock Wave Lithotripsy (ESWL), we implemented a two-phase continuum model for cavitating flow and applied it to the simulation of bubble cloud dynamics in an electro-hydraulic lithotripter. Through the combination of a WENO shock capturing scheme, curvilinear coordinates system and ensemble averaged mixture model, we computed the evolution of the lithotripsy shock wave and the concomitant cavitation field. In this paper, we present the results for three different configurations: a single-pulse lithotripter (free field), a single-pulse lithotripter with rigid artificial kidney stone at the focal point, and a dual-pulse lithotripter. Qualitative and quantitative comparisons of the numerical results to experimental observations are also included.

Shared-Memory Parallelization for Two-Way Coupled Euler–Lagrange Modeling of Cavitating Bubbly Flows

2015 ◽  
Vol 137 (12) ◽  
Author(s):  
Jingsen Ma ◽  
Chao-Tsung Hsiao ◽  
Georges L. Chahine
Keyword(s):  
Shared Memory ◽  
Bubble Dynamics ◽  
Bubbly Flows ◽  
Processing Unit ◽  
Computational Domain ◽  
Time Step ◽  
Two Phase ◽  
Bubble Cloud ◽  
Cloud Dynamics ◽  
The Continuum

Cavitating and bubbly flows are encountered in many engineering problems involving propellers, pumps, valves, ultrasonic biomedical applications, etc. In this contribution, an openmp parallelized Euler–Lagrange model of two-phase flow problems and cavitation is presented. The two-phase medium is treated as a continuum and solved on an Eulerian grid, while the discrete bubbles are tracked in a Lagrangian fashion with their dynamics computed. The intimate coupling between the two description levels is realized through the local void fraction, which is computed from the instantaneous bubble volumes and locations, and provides the continuum properties. Since, in practice, any such flows will involve large numbers of bubbles, schemes for significant speedup are needed to reduce computation times. We present here a shared-memory parallelization scheme combining domain decomposition for the continuum domain and number decomposition for the bubbles; both selected to realize maximum speedup and good load balance. The Eulerian computational domain is subdivided based on geometry into several subdomains, while for the Lagrangian computations, the bubbles are subdivided based on their indices into several subsets. The number of fluid subdomains and bubble subsets matches with the number of central processing unit (CPU) cores available in a shared-memory system. Computation of the continuum solution and the bubble dynamics proceeds sequentially. During each computation time step, all selected openmp threads are first used to evolve the fluid solution, with each handling one subdomain. Upon completion, the openmp threads selected for the Lagrangian solution are then used to execute the bubble computations. All data exchanges are executed through the shared memory. Extra steps are taken to localize the memory access pattern to minimize nonlocal data fetch latency, since severe performance penalty may occur on a nonuniform memory architecture (NUMA) multiprocessing system where thread access to nonlocal memory is much slower than to local memory. This parallelization scheme is illustrated on a typical nonuniform bubbly flow problem, cloud bubble dynamics near a rigid wall driven by an imposed pressure function (Ma et al., 2013, “Euler–Lagrange Simulations of Bubble Cloud Dynamics Near a Wall,” International Mechanical Engineering Congress and Exposition, San Diego, CA, Nov. 15–21, Paper No. IMECE2013-65191 and Ma et al., 2015, “Euler–Lagrange Simulations of Bubble Cloud Dynamics Near a Wall,” ASME J. Fluids Eng., 137(4), p. 041301).

Numerical study of acoustically driven bubble cloud dynamics near a rigid wall

2018 ◽  
Vol 40 ◽  
pp. 944-954 ◽  
Author(s):  
Jingsen Ma ◽  
Chao-Tsung Hsiao ◽  
Georges L. Chahine
Keyword(s):  
Numerical Study ◽  
Rigid Wall ◽  
Bubble Cloud ◽  
Cloud Dynamics
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