MODEL COMPARISON FOR ACOUSTIC SCATTERING BY A SPHERICAL AIR BUBBLE IN WATER

2002 ◽  
Vol 250 (4) ◽  
pp. 723-744 ◽  
Author(s):  
C.-C. WANG ◽  
Z. YE
Keyword(s):  
Model Comparison ◽  
Acoustic Scattering ◽  
Air Bubble

Propeller Cavitation Induced Hull Pressure Reduction by Air-Bubble Layer

2013 ◽  
Author(s):  
Jeung-Hoon Lee ◽  
Hyoung-Gil Park ◽  
Jin-Hak Kim ◽  
Kyung-Jun Lee ◽  
Jong-Soo Seo
Keyword(s):  
Acoustic Scattering ◽  
Destructive Interference ◽  
Primary Concern ◽  
Pressure Amplitude ◽  
Pressure Reduction ◽  
Noise Sources ◽  
Air Bubble ◽  
Excessive Consumption ◽  
Bubble Layer ◽  
The Cost

Cavitation generated by a marine propeller is a primary concern among the possible vibration- and noise- sources in commercial ships. By exploiting the compressibility of air, there have been many attempts to form an air-bubble layer underneath the stern-hull surface above the propeller, and consequently to isolate the cavity-induced pressure wave across the layer. However, it could not be popularly used because the cost was so expensive to deliver a huge amount of air for a sufficient isolation performance. In this work, full-scale ship measurements reveal that a significant reduction of pressure-amplitude is possible at the outside of an air-bubble layer, where the isolation effect is not involved. Moreover a hull-vibration reduction of approximately 75% was found to be achievable. Instead of excessive consumption of air, considerably small amount is necessary for a reduction of cavity-induced pressure amplitude, which can make the constitution of relevant system simple. Hence the purpose of this study is to provide a physical proof for such a beneficial phenomenon. By approximating the solution of acoustic scattering from a bubble, we find that phase-reversal reflection provoking a destructive interference is the main reason for a pressure reduction outside the layer.

scholarly journals Tunneling effects in resonant acoustic scattering of an air bubble in unbounded water

2016 ◽  
Vol 88 (2) ◽  
pp. 765-790 ◽  
Author(s):  
ANDRÉ G. SIMÃO ◽  
LUIZ G. GUIMARÃES
Keyword(s):  
Physical Model ◽  
Acoustic Scattering ◽  
Natural Oscillation ◽  
Potential Scattering ◽  
Underwater Sound ◽  
Quality Factors ◽  
Partial Wave Expansion ◽  
Storage Mechanism ◽  
Air Bubble ◽  
Oscillation Modes

Abstract The problem of acoustic scattering of a gaseous spherical bubble immersed within unbounded liquid surrounding is considered in this work. The theory of partial wave expansion related to this problem is revisited. A physical model based on the analogy between acoustic scattering and potential scattering in quantum mechanics is proposed to describe and interpret the acoustical natural oscillation modes of the bubble, namely, the resonances. In this context, a physical model is devised in order to describe the air water interface and the implications of the high density contrast on the various regimes of the scattering resonances. The main results are presented in terms of resonance lifetime periods and quality factors. The explicit numerical calculations are undertaken through an asymptotic analysis considering typical bubble dimensions and underwater sound wavelengths. It is shown that the resonance periods are scaled according to the Minnaert’s period, which is the short lived resonance mode, called breathing mode of the bubble. As expected, resonances with longer lifetimes lead to impressive cavity quality Q-factor ranging from 1010 to 105. The present theoretical findings lead to a better understanding of the energy storage mechanism in a bubbly medium.

Comments on "acoustic scattering by an air bubble near the sea surface" [and reply]

1996 ◽  
Vol 21 (2) ◽  
pp. 233 ◽  
Author(s):  
M. Strasberg ◽  
G.C. Gaunaurd ◽  
H. Huang
Keyword(s):  
Acoustic Scattering ◽  
Sea Surface ◽  
Air Bubble

Identifying suboptimalities with factorial model comparison

2018 ◽  
Vol 41 ◽  
Author(s):  
Wei Ji Ma
Keyword(s):  
Experimental Design ◽  
Model Comparison ◽  
Process Models ◽  
Multiple Forms ◽  
Factorial Experimental Design ◽  
Factorial Model ◽  
Multiple Components ◽  
The Many

AbstractGiven the many types of suboptimality in perception, I ask how one should test for multiple forms of suboptimality at the same time – or, more generally, how one should compare process models that can differ in any or all of the multiple components. In analogy to factorial experimental design, I advocate for factorial model comparison.

ASSESSMENT OF ANATOMICAL & FUNCTIONAL SUCCESS IN EXTERNAL DACRYOCYSTORHINOSTOMY BY AIR BUBBLE TEST

2019 ◽  
Vol 3 (9) ◽  
Author(s):  
Dr. Vikas Tantuway
Keyword(s):  
Case Series ◽  
Invasive Procedure ◽  
Nasolacrimal Duct ◽  
Good Tool ◽  
Predictive Values ◽  
Reliability Indices ◽  
Air Bubble ◽  
Bubble Test ◽  
External Dacryocystorhinostomy ◽  
Anatomical Success

Aim: To assess reliability indices of Air Bubble Test (ABT) for anatomical and functional success in external Dacryocystorhinostomy (DCR). Methods: Prospective case series of nasolacrimal duct obstruction underwent DCR. Functional success defined as Munk score 0 & 1 & anatomical success as free irrigation at followup.ABT performed by putting antibiotic drops into eye& asking patient to exhale while keeping nose & mouth closed. Formation of bubbles at punctum considered as positive test. Specificity, sensitivity, positive & negative predictive values calculated. Results: There were 103 DCR in 97 patients(23 male,74 female)with mean age 45.56 yr. Anatomical and functional success was 99.02% & 98.05%, respectively.ABT showed sensitivity 96.07%, specificity 100% for anatomical success after DCR. Sensitivity and specificity were 97.02% & 100% for functional success. Conclusion: As non-invasive procedure ABT is a good tool to assess success of DCR, though lacrimal syringing remains the gold standard. Keywords: Anatomical, Dacryocystorhinostomy & Air Bubble Test.

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