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Reynolds Stress Distribution in Roll-up Motion of Two-stream Mixing Layer
二平行流混合層流れにおける巻上げ運動中のレイノルズ応力分布

時政, 辰夫 ; 長瀬, 洋一 ; 原, 正明 ; Tokimasa, Tatsuo ; Nagase, Yoichi ; Hara, Masaaki

化学工学論文集, 1984, Vol.10(1), pp.96-101 [Periódico revisado por pares]

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  • Reynolds Stress Distribution in Roll-up Motion of Two-stream Mixing Layer

  • Título:
    二平行流混合層流れにおける巻上げ運動中のレイノルズ応力分布
  • Autor: 時政, 辰夫 ; 長瀬, 洋一 ; 原, 正明 ; Tokimasa, Tatsuo ; Nagase, Yoichi ; Hara, Masaaki
  • Assuntos: Fluid Mechanics ; Momentum Transfer ; Mixing Layer ; Reynolds Stress ; Vortex
  • É parte de: 化学工学論文集, 1984, Vol.10(1), pp.96-101
  • Descrição: 前報に続いて, ペアリングを生じる前の二次元的渦状運動の成長によって特徴づけられる混合層流れ初期の段階でのレイノルズ応力の測定が行われた.最初に, 混合層幅にわたる応力の総和は, 下流方向距離に対して周期的変化を示すことが見い出せた.応力の総和は, 巻上げ初期に急激に増加し, 次に渦同士の相互干渉のため減少してゆく.この周期性は, Hussainらにより指摘された渦合体期間中での応力の周期性と類似するものである.
    一個の渦内部のレイノルズ応力-u'v'分布は, 1) 年齢の若い渦では, 高流速側からのエントレインメトにともなう大きな負の領域と低流速側からのエントレイメントにともなう大きな正の領域が存在している.2) 高流速側と低流速側流体の二重ロール構造によって特徴づけられる渦が相互干渉をはじめている期間でのかなり年齢の古い渦では, 180°位相ずれを生じた高流速側と低流速側の境界付近に二つの大きな正の領域がある.この領域から90°位相がずれた所に小さな負の領域が見い出せた.結果として, レイノルズ応力の正と負の領域は, 渦を円形から楕円形へと変形させる.

    Following work by the authors reported previously, Reynolds stress measurement has been carried out for the initial stage of mixing-layer flow characterized by a growing-up period of two-dimensional vortical motion before its pairing.
    It was found that the sum of the stresses over the mixing-layer width showed a periodic variation with downstream distance. The sum increased abruptly at the beginning of the roll-up and then decreased because of mutual interaction between vortices. This periodicity should be conjugated with that in the vortex-pairing period, which was pointed out by Hussain et al.
    Reynolds stress, -ρu'v', distribution in a vortex was as follows : (1) with respect to a young vortex, there was a large but minus region with entrainment from the high-velocity side and a large plus region with entrainment from the low-velocity side; (2) with respect to a rather old vortex caused by the mutual interaction of vortices, which was characterized by a double-roll structure of high-and low-velocity fluid, two of the large plus regions laid around the boundary between the high and low velocities with a 180-degree phase lag and a pair of small minus regions were also found on a 90-degree phase lag relative to the plus region. Thus the plus and minus regions of the Reynolds stress transform from a round vortex to an elongated one.

  • Idioma: Japonês

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