2006 Fiscal Year Final Research Report Summary
Creation of a cluster of cavitation bubbles using diffusing droplets and its extension to sonoluminescence
| Project/Area Number |
16560138
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | The University of Electro-Communications |
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Principal Investigator |
HAYASHI Shigeo The University of Electro-Communications, Faculty of Electro-Communications, Professor, 電気通信学部, 教授 (60126357)
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| Co-Investigator(Kenkyū-buntansha) |
HATANAKA Shin-ichi The University of Electro-Communications, Faculty of Electro-Communications, Assistant Professor, 電気通信学部, 助手 (40334578)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Acoustic cavitation / Diffusion / Viscous drops / Concentrated salt solutions / Sulfuric acid |
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| Research Abstract |
The purpose of the present research program is to investigate experimentally how a viscous droplet, injected into water, plays a role in creating many bubbles, which may eventually result in a single bubble. The process is complicated and difficult to manage, as noted by Naser Harba. More fundamental investigation has thus been carried out.
1)Hydrodynamical behavior of a viscous diffusing droplet.
First, with no ultrasound droplets of glycerol were let fall from a position 5 mm above the surface, but the droplets floated as long as its density was heavier than the solution by less than 0.02 g/cm^3. Diffusion may have helped to gain the buoyancy. Next, if ultrasound was applied, the droplets evaded the position where bubbles were otherwise trapped, suggesting that Naser Harba painstakingly observed those diffusing processes.
2)Analysis of light-scattering data and related subjects.
Mie-scattering data for multiple bubbles formed from an injected glycerol droplet were analyzed, with the assumption that bubbles obeyed the Rayleigh-Plesset equation. It turned out that the scattering data were affected by saturation due to light. Computer programs were developed for analysis of bubbles and drops and for jittering of pulses on the digital oscilloscope, which may mislead to false time-train signals.
3)Sonoluminescence from concentrated sulfuric acid.
Sulfuric acid is also viscous, and sonoluminescence from it was investigated at several frequencies.
4)Numerical simulation of Moire patterns for diffusing droplets
Moire patterns were produced for a distribution of refractive index, which might mimic droplets isotropically diffusing within water.
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