2003 Fiscal Year Final Research Report Summary
Study on the bubble sound induced by the impact of a water drop on a liquid surface and exploration of possibility of sound control
| Project/Area Number |
14550135
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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 | Hokkaido University of Education |
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Principal Investigator |
TOMITA Yukio Hokkaido University of Education, Faculty of Education, Hakodate, Professor, 教育学部・函館校, 教授 (00006199)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Water Droplet / Air Bubble / Bubble Sound / Splash / Instability / Capillary Wave / Suikinkutsu |
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| Research Abstract |
By changing the drop diameter d_D and dropping height H (i.e.impact velocity V_<imp>), we investigated the surface deformation and air bubble formation induced by the impact of a water drop on a water surface. A detailed experiment was carried out for the irregular bubble entrainment region which is closely related to the sound condition of Suikinkutsu. The results are summarized in the followings.
(1)In the irregular bubble entrainment region, we found three types of mechanisms for air bubble formations. Especially available sounds are caused by the oscillation of air bubbles generated by the following mechanisms. The first one is the case where an air bubble is generated by the impact of a satellite droplet with a rising water surface. The second pattern of air bubble formation is associated with the surface closure during the falling process of the water column.
(2)Even in the irregular bubble entrainment legion, there is some area of the (d_D-V_<imp>) condition where an air bubble is regularly entrained due to the impact of a satellite drop with the rising bottom of the cavity surface. On the other hand, during the falling process of the water column air bubbles can be generated randomly, resulting in a variety of underwater sounds. These sounds often have a wide range of frequencies.
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