尾流成长多尺度特性及尾流间相互作用机理研究

Being one of the most important topics in turbulence research, wake-interactions can be widely found in various industrial fields and numerous environmental engineering. Within this project, both characteristics of a single wake and wake-interactions will be thoroughly investigated by means of theoretical analysis, direct numerical simulation and experimental study. This project includes the following three aspects. (1) The self-sustaining mechanism of turbulent/nonturbulent interface and the self-similarity/self-preservation characteristics of a turbulent wake will be investigated. Another important purpose of this study is to clarify the intrinsic physical relationship between the interface, coherent structure, local energy dissipation and wake growth. Consequently, we could obtain a detailed description of the multi-scale characterization of the growth of a single wake. (2) In the intermittent region of a dual-wake flow, the assumptions of the K41 theory do not hold. The appearance of the -5/3 scaling-law in the intermittent region is studied to clarify the effects of boundary conditions, large-scale motion (vortex shedding), vortex structures and elucidate energy cascade mechanism in physical space. (3) This project also focuses on the influences of multi-scale arrangement of cylinders on vortex shedding and evolution mechanism of coherent structure. The Lagrangian characteristics in the multi-scale wake flow are going to be clarified, and the mechanism of passive flow control by using multi-scale arrangement will be explored. Based on the above research, a complete description of the multi-scale characteristics of wakes and their interactions can be reached.

尾流是湍流理论研究的一个重要领域，同时在工业应用和环境工程中，也存在大量尾流间相互作用问题。本项目拟围绕单束尾流成长多尺度特性及尾流间相互作用机理开展理论分析、直接数值模拟和实验验证。具体包括：（1）研究湍流-非湍流界面层自我维持机制，探讨尾流自相似/自我保存特性，阐明流场中界面层、拟序结构和局部能量耗散与尾流成长的内在物理联系，进而完善对单束尾流成长的多尺度刻画；（2）双束尾流间歇区不满足K41理论假设，对间歇区内出现的-5/3标度律展开研究，明确边界条件、大尺度运动（涡脱落）及涡结构断裂和重联对能量级串的影响及能量在物理空间上传递特性；（3）揭示柱体分形布置对湍流场中涡旋脱落以及拟序结构演化机理影响，探索分形布置对流动被动控制作用机理。阐明分形尾流场中拉格朗日传质输运特性。通过本项目研究，我们将实现对尾流多尺度统计特性及尾流间相互作用机理全面刻画。

尾流是湍流理论研究的一个重要领域，同时在工业应用和环境工程中，也存在大量尾流间相互作用问题。本项目针对单束尾流成长多尺度特性及尾流间相互作用机理开展了理论分析、直接数值模拟和实验验证。具体包括：1、揭示了湍流-非湍流界面层自我维持机制和成长机制，通过对拟序结构开展统计研究，证实了流场自相似/自我保存特性和拟序结构之间的物理关联，同时阐明了流场中界面层、拟序结构和局部能量耗散与尾流成长的内在物理联系；2、展开了双束尾流间歇区内的-5/3标度律和能量级串特性研究，通过二阶结构函数明确能量在物理空间上传递特性，理论推导并证实了间歇区能量耗散常数的表达式；3、揭示了柱体分形布置对湍流场中涡旋脱落以及拟序结构演化机理影响，探索分形布置对流动被动控制作用机理。同时阐明了分形尾流场中拉格朗日传质输运特性。通过项目研究，实现了尾流多尺度统计特性及尾流间相互作用机理全面刻画。