高磁化率磁性流体界面の非線形多分岐不安定のパターンセンジング

高磁化率磁流体界面非线性多支化不稳定性的模式传感

• 批准号: 05452150
• 负责人: 山根 隆一郎
• 金额: $ 4.03万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1993
• 资助国家: 日本
• 起止时间: 1993 至 无数据
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-05452150/
• 关键词: 流体工学; 磁性流体力学; 非線形不安定波; スパイク; 振動パターン; 交流磁場; 高透磁率磁性流体; 周波数特性

本研究では,鉛直交流磁場作用下でのスパイク状非線形界面の挙動に関して,まず,その基礎となる単一スパイクについて,スパイク形状を半回転楕円体と仮定した場合のスパイク振動について近似解析を行い,さらに高速度ビデオカメラやレーザ外形測定器等を用いた水ベース磁性流体の不安定波のパターンセンジングを行い,スパイク形状や印加磁場に対する振動の周波数特性を実験的に調べた.また,SOLA-VOF法によってスパイク形状や,スパイク内部の流動の様子を数値解析により調べた.さらに,窒化鉄磁性流体(高透磁率磁性流体)を用い水平交流磁場作用下での界面挙動を調べた.その結果,次のような結論を得た.(1)スパイクの振動パターンは,印加磁場周波数と同じ周波数で振動する場合が1通り,2倍の周波数で振動する場合には2通りのパターンがある.(2)印加磁場周波数の2倍の周波数で振動する場合は単一スパイクを形成するが,印加磁場周波数と同じ周波数で振動する場合には,単一スパイクが一旦複数のスパイクに分裂し,さらに単一のスパイクに復帰する過程を交互に繰り返しながら振動する特異な挙動を示す.この特異な振動パターンは特定な周波数,印加磁場強さにおいて発生し,その発生領域は水平面で発生する振動不安定波の発生領域と酷似している.(3)スパイクの振動振幅が大きくなる共振周波数が存在する.(4)スパイクの突起形状は磁化率および表面張力に強く依存し,磁化率が大きく表面張力が小さいほどスパイク高さは高くなり突起先端は鋭く尖る.(5)高透磁率磁性流体では外部磁場の分布を著しく変化させるため,有限容器内に満たされている場合には低透磁率磁性流体では無視し得る側壁部の挙動が全体の界面挙動に強く影響を及ぼす.実験から,低透磁率磁性流体では不安定波が現れない一様水平磁場作用下でも印加磁場方向と直交する波数ベクトルを有する不安定波の発生が確認された.

In this study, the basic theory of vibration at a nonlinear interface in a vertical alternating magnetic field is studied. The approximate analysis of vibration at a nonlinear interface in a vertical alternating magnetic field is carried out. The approximate analysis of vibration at a nonlinear interface in a vertical alternating magnetic field is carried out. The approximate analysis of vibration at a nonlinear interface in a vertical alternating magnetic field is carried out. The frequency characteristics of the vibration caused by the shape and magnetic field are adjusted. The SOLA-VOF method is used to analyze the shape and number of flow elements in the interior. In this paper, ferromagnetic fluids (magnetic fluids with high permeability) are modulated by using horizontal alternating magnetic fields. The result of the experiment was obtained. (1)When the frequency of the magnetic field is equal to the frequency of the magnetic field, the frequency of the magnetic field is equal to the frequency of the magnetic field. When the frequency of the magnetic field is equal to the frequency of the magnetic field, the frequency of the magnetic field is equal to the frequency of the magnetic field. (2)When the frequency of the magnetic field is twice the frequency of the vibration, the frequency of the magnetic field is equal to the frequency of the vibration. When the frequency of the magnetic field is equal to the frequency of the vibration, the frequency of the magnetic field is equal to the frequency of the vibration. The special vibration wave is generated at a certain frequency, and the magnetic field strength is increased. The vibration unstable wave is generated in a similar field to the horizontal plane. (3)The vibration amplitude is large, and the resonance frequency is large. (4)The shape of the protrusion is strongly dependent on the magnetic susceptibility and surface tension. The magnetic susceptibility is large. The surface tension is small. The protrusion tip is sharp. (5)The distribution of the external magnetic field of the magnetic fluid with high magnetic permeability is changed. In the case of magnetic fluid with low magnetic permeability in a finite container, the movement of the side wall is ignored. The influence of the movement of the whole interface is strong. The occurrence of unstable waves in magnetic fluids with low magnetic permeability is confirmed under the action of a horizontal magnetic field.