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2006 Fiscal Year Final Research Report Summary

Mechanism and its application of bubble sounds induced by the drop impact in the irregular entrainment region

Research Project

Project/Area Number 17560132
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Fluid engineering
Research InstitutionHokkaido University of Education

Principal Investigator

TOMITA Yukio  Hokkaido University of Education, Faculty of Education, Professor, 教育学部, 教授 (00006199)

Co-Investigator(Kenkyū-buntansha) SATO Kotaro  Kogakuin University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (80252625)
Project Period (FY) 2005 – 2006
KeywordsWater Droplet / Bubble / Impact Phenomena / Liquid Jet / Water Column / Underwater Sound / Surface Breakup / Suikinkutsu
Research Abstract

An experiment was carried out for investigating the mechanism of surface breakup due to drop impact on a free surface and induced underwater sounds for the range of Froude number Fr 300. Application of these sounds to an open-type Suikinkutsu was also examined.
(1) A falling drop changes its shape oscillatory depending on the Weber number, then impacts onto a water surface. When a drop impacts with the shape being prolate the resultant splash is relatively weak compared to the oblate drop impact case.
(2) Three times of underwater sounds were generated for a single shot of drop impact. The first sound resulted from the oscillation of a single air bubble formed as a result of the satellite drop impact on the bottom of a cavity under contracting, and the second sound was due to the oscillation of air bubbles generated during the collapse of a water column. The formation of these air bubbles strongly depends on the Fr number, We number (or Bond number) and the aspect ratio of a drop at impa … More ct, although involving probability characteristics. An air bubble entrapped into a water column plays an important role in elevating the probability of contact between the column surface and curved free surface.
(3) Once drop impact is generated inside a water jar, the sounds propagate through the water surface into the air inside the jar and reflect many times on the wall surface of the jar, producing a reverberant sound with a long duration which is a peaceful and healing sound. An experiment was also performed by using drops with the average diameters of 6.2, 7.2 and 7.8mm in order to investigate the effects of water flow rate and water temperature on the Suikinkutsu sound. For generating a powerful sound of Suikinkutsu, therefore, water temperature should be maintained as low as possible.
The results mentioned above have been presented and published at various meetings. More recently our paper associated with the surface breakup and bubble sounds has been accepted for publication in the Journal of Fluid Mechanics. Less

  • Research Products

    (14 results)

All 2007 2006 2005

All Journal Article (13 results) Book (1 results)

  • [Journal Article] Surface breakup and air bubble formation by drop impact in the irregular entrainment region2007

    • Author(s)
      Y.Tomita
    • Journal Title

      Journal of Fluid Mechanics (Acceptance for publication)

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Surface breakup and air bubble formation by drop impact in the irregular entrainment region2007

    • Author(s)
      Y.Tomita
    • Journal Title

      Acceptance for publication in the Journal of Fluid Mechanics

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] 水滴の水面衝突による水柱の挙動と第2気泡音の発生機構2006

    • Author(s)
      斉藤 竜也
    • Journal Title

      日本産業技術教育学会北海道支部会研究論文集 第19号

      Pages: 75-78

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] 開放型水琴窟の音響特性に及ぼす落下水塊の諸特性の影響2006

    • Author(s)
      鴈原 俊太郎
    • Journal Title

      日本産業技術教育学会北海道支部会研究論文集 第19号

      Pages: 79-82

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] イレギュラー気泡取り込み領域における気液界面の分裂挙動2006

    • Author(s)
      冨田 幸雄
    • Journal Title

      日本混相流学会年会講演会2006 講演論文集

      Pages: 190-191

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] イレギュラー気泡取り込み領域における気液界面分裂と水中過渡音響2006

    • Author(s)
      冨田 幸雄
    • Journal Title

      日本機械学会年会講演会2006 講演論文集(2) No.06-1

      Pages: 449-450

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Dynamics of a water column generated by the drop impact and induced bubble sounds (in Japanese)2006

    • Author(s)
      T.Saito
    • Journal Title

      Hokkaido Journal of the Japanese Society of Technical Education Vol.19

      Pages: 75-78

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Effects of water mass on the characteristics of sounds generated by an open-type of Suikinkutsu (in Japanese)2006

    • Author(s)
      S.Ganbara
    • Journal Title

      Hokkaido Journal of the Japanese Society of Technical Education Vol.19

      Pages: 79-82

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Dynamics of surface breakup in the irregular bubble entrainment region (in Japanese)2006

    • Author(s)
      Y.Tomita
    • Journal Title

      Proceedings of the JSMF Annual Meeting 2006

      Pages: 190-191

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Surface breakup and transient underwater sounds in the irregular bubble entrainment region (in Japanese)2006

    • Author(s)
      Y.Tomita
    • Journal Title

      Proceedings of the Mechanical Engineering Congress MECJ-06, Vol.2, No.06-1

      Pages: 449-450

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] 12.3 Bubble dynamics2006

    • Author(s)
      Y.Tomita
    • Journal Title

      In JSME Mechanical Engineer's Handbook, Fundamentals, α4 : Fluids Engineering(ed.JSME)(Maruzen)(in Japanese)

      Pages: a4137-a4139

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] 水滴の水面衝突による界面運動と空気泡の生成機構2005

    • Author(s)
      冨田 幸雄
    • Journal Title

      日本混相流学会年会講演会2005 講演論文集

      Pages: 479-480

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Surface dynamic and air bubble formation due to drop impact on a free surface (in Japanese)2005

    • Author(s)
      Y.Tomita
    • Journal Title

      Proceedings of the JSMF Annual Meeting 2005

      Pages: 479-480

    • Description
      「研究成果報告書概要(欧文)」より
  • [Book] 機械工学便覧 基礎編 α4編 流体工学 12.3 気泡の力学2006

    • Author(s)
      冨田 幸雄(分担執筆:日本機械学会編)
    • Total Pages
      3
    • Publisher
      丸善
    • Description
      「研究成果報告書概要(和文)」より

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Published: 2008-05-27  

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