Structure and Dynamics of Turbulent Elementary Vortices

湍流基本涡的结构和动力学

基本信息

批准号：
12125204
负责人：
KIDA Shigeo
金额：
$ 38.66万
依托单位：
Kyoto University (2003)National Institute for Fusion Science (2000-2002)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

In the study of the basic properties of the elementary vortices, the spatial distribution and the Reynolds number dependence of their physical characteristics have been clarified quantitatively, suggesting that the elementary vortices may keep their dynamical importance at larger Reynolds numbers. An automatic chasing scheme of vortices has been developed to find the anti-parallel approach of vortices, which stretch the fluia lines and surfaces exponentially in time. The compressibility of fluids has been shown to induce vortex waves and to suppress the vortex growth. A new dynamo phenomenon by interactions between convection vortices and magnetic fields has been discovered in MHD turbulence. unstable periodic motions accompanying the generation and breakdown of the elementary vortices has been found in Couette turbulence. In the study of basic dynamical properties of the elementary vortices, the interaction of large-scale coherent vertical structures and turbulent field has been investigated with or without the axial flow in the coherent vortices. In the former case, fine scale vortices are generated and wrapped around the vortex surface, and axi-symmetric bending vortices are generated inside the coherent vortex. In the latter, on the other hand, vortex rings produced from the elementary vortices enhance the energy dissipation at the periphery of the vortex core. In a Poiseuille turbulence, longitudinal Vortex and streak structures have been observed in the outer layer like as in the inner layer.

在对基本涡旋基本性质的研究中，定量地阐明了基本涡旋物理特性的空间分布和雷诺数依赖性，这表明基本涡旋在较大的雷诺数下可能保持其动力学重要性。我们开发了一种涡流自动追踪方案来寻找涡流的反平行方法，该方法可以及时地以指数方式拉伸流体线和表面。流体的可压缩性已被证明可以引起涡流波并抑制涡流的增长。在 MHD 湍流中发现了对流涡旋和磁场之间相互作用的新发电机现象。在库埃特湍流中发现了伴随基本涡旋的产生和破裂的不稳定周期性运动。在基本涡旋基本动力学性质的研究中，研究了大尺度相干垂直结构与湍流场的相互作用，有或没有相干涡旋中的轴向流。在前一种情况下，产生细尺度涡旋并缠绕在涡旋表面上，并且在相干涡旋内部产生轴对称弯曲涡旋。另一方面，在后者中，基本涡产生的涡环增强了涡核外围的能量耗散。在泊肃叶湍流中，与内层一样，在外层中观察到纵向涡流和条纹结构。