An experimental study on an instability of a baroclinic flow caused by a surface cooling in a rotating fluid

旋转流体表面冷却引起斜压流不稳定性的实验研究

• 批准号: 14340138
• 负责人: NAKAMURA Kozo
• 金额: $ 9.54万
• 依托单位: Independent Administrative Institution, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) (2004)The University of Tokyo (2002-2003)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14340138/
• 关键词: Baroclinic instability; Horizontal Convection; Rotating fluid experiment; Boundary layer; Cool island circulation; Turbulence; Heat island circulation; 回転流体

An axisymmetric cool island circulation that is generated when a circular region of the bottom of a semi-infinite fluid is cooled in a rotating frame and associated baroclinic instability waves are studied by means of a laboratory experiment on the large turntable of the Meteorological Research Institute, a theoretical consideration and a numerical experiment.In the laboratory experiment, a liquid crystal sheet at the bottom of the water tank is used to visualize the temperature distribution near the bottom and PIV(Particle Image Velocimeter) is used to measure the horizontal distributions of the horizontal velocity. The following results are found : When the basic rotation is either absent or small, the cool island circulation remains axisymmetric. When it becomes larger than a critical value, disturbances with circumferential wavenumber 2-3 appear. As the basic rotation is increased further, the wavenumber of the disturbances increase and the flow field becomes chaotic. It is also found that lycopodium is the most suitable tracer particle for PIV measurement.Additional theoretical considerations reveal that the cool island circulation has three different regimes depending on the non-dimensional angular velocity and non-dimensional stratification : Diffusion, gravity current and gravity wave regimes. The only non-linear regime is the gravity current regime, and is always unstable for a slab-symmetric case. For an axisymmetric case, however, the flow is stable when the basic rotation is small and the radius of deformation is larger than the diameter of the cool island.

本文通过气象研究所大转台实验、理论研究和数值试验，研究了旋转坐标系中半无限流体底部圆形区域冷却时产生的轴对称冷岛环流及其斜压不稳定波。在实验中，在水槽底部放置液晶片，观察水槽底部附近的温度分布，用PIV（ParticleImageVelocimeter）测量水平速度的水平分布。结果表明：当基本自转不存在或很小时，冷岛环流仍保持轴对称。当它变得大于一个临界值时，出现周向波数为2-3的扰动。随着基本旋转的进一步增加，扰动波数增加，流场变得混沌。另外，根据无因次角速度和无因次层结的不同，冷岛环流存在三种不同的区域：扩散区、重力流区和重力波区。唯一的非线性政权是重力流政权，总是不稳定的板对称的情况下。对于轴对称情况，当基本转动较小且变形半径大于冷岛直径时，流动是稳定的。

项目成果

Mouri, H., Hori, A., Kawashima, Y.: "Vortex tubes in velocity fields of laboratory isotropic turbulence : Dependence on the Reynolds number"Physical Review E. 67. 016305 (2003)

Mouri, H.、Hori, A.、Kawashima, Y.：“实验室各向同性湍流速度场中的涡管：对雷诺数的依赖性”物理评论 E. 67. 016305 (2003)

気象ハンドブック(第3版)第11章第1節 気象の流体実験

气象手册（第3版）第11章第1节气象流体实验

• 发表时间: 2005
• 作者: A.Shirakawa;K.Takaichi;H.Yagi;M.Tanisho;J.-F.Bisson;J.Lu;K.Ueda;T.Yanagitani;A A.Kaminskii;Gyanu Ratna Tuladhar;新野 宏(分担執筆)
• 通讯作者: 新野 宏(分担執筆)

Vortex tubes in turbulence velocity fields at Reynolds numbers Re_=300-1300

雷诺数 Re_=300-1300 的湍流速度场中的涡流管

• 发表时间: 2004
• 期刊: Physical Review E70
• 作者: Mouri;H.;A.Hori;Y.Kawashima
• 通讯作者: Y.Kawashima

Vortex tubes in turbulence velocity fields at Reynolds numbers Re_λ〜300-1300

雷诺数 Re_λ〜300-1300 湍流速度场中的涡管

• 发表时间: 2004
• 期刊: Physical Review E70
• 作者: Mouri;H.;A.Hori;Y.Kawashima
• 通讯作者: Y.Kawashima

Hideaki Mouri, M.Takaoka, A.Hori, Y.Kawashima: "Probability density function of turbulent velocity fluctuations in a rough-wall boundary layer"Physical Review E. 68. article number:036311 (2003)

Hideaki Mouri、M.Takaoka、A.Hori、Y.Kawashima：“粗糙壁边界层中湍流速度波动的概率密度函数”物理评论 E. 68。文章编号：036311 (2003)