Coordination Funds

协调基金

• 批准号: 316221523
• 负责人: Professor Dr. Jörg Schumacher
• 金额: --
• 依托单位: Fachgebiet Strömungsmechanik
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/316221523?language=en
• 关键词: Coordination; Funds

The classical picture of turbulence is that turbulent fluid motion is characterized by a cascade of vortices and swirls of different sizes that give rise to a featureless and stochastic fluid motion. Our daily experience shows, however, that turbulent flows in nature and technology are often organized in prominent large-scale and long-living structures that can cause extreme fluctuations. The focus of the Priority Programme are Turbulent Superstructures, i.e., patterns whose coherence does not stop at the natural scale, such as the boundary layer height, but extends over much larger scales. The study of superstructures is now possible due to significant advances in measurement techniques, numerical simulation, and mathematical characterization. Tomographic laser-based measurement techniques can track the dynamics of turbulent structures with unprecedented resolution in space and time. Direct numerical simulations on massively parallel supercomputers have advanced to a level where turbulent flows in extended domains can be simulated at sufficiently high Reynolds numbers and in parameter ranges where superstructures emerge. Efficient methods to characterize dominant vortices and flow structures and to determine the transport across their boundaries as well as their dynamical evolution have been developed in applied mathematics. Computer science provides efficient algorithms for the visualization and fast processing of structures in very large data sets.The aim of the present Priority Programme is to integrate the different recent advances to arrive at a comprehensive characterization and understanding of turbulent superstructures. More detailed, this includes the experimental characterization of superstructures, direct numerical simulations of turbulent large-scale and superstructures, and their detection and identification by different Lagrangian and Eulerian methods. Furthermore, we want to analyse the origin of turbulent superstructures from primary and secondary instabilities, the role of symmetries and boundary conditions for their formation and dynamics. We want to understand their role for the turbulent transport, in particular that of their interfaces. Finally, we want to develop reduced models to describe their dynamics effectively and develop strategies to control these structures. In order to keep the program focused, it is intended to study singlephase, wall-bounded flows in simple Cartesian and parallel geometries, driven by shear or buoyancy. It is only by joining forces across the various disciplines that we will be able to achieve a better characterization of turbulent superstructures, to extract information about their essential properties and thus to obtain a comprehensive understanding of their impact on turbulence statistics and turbulent transport.

湍流的经典图像是湍流流体运动的特征在于引起无特征和随机流体运动的不同大小的漩涡和漩涡的级联。然而，我们的日常经验表明，自然界和技术中的湍流往往是以突出的大规模和长期存在的结构组织起来的，这些结构可能导致极端的波动。优先方案的重点是湍流上层建筑，即，其相干性并不局限于自然尺度（如边界层高度），而是扩展到更大的尺度。由于测量技术、数值模拟和数学表征的显著进步，对超结构的研究现在是可能的。基于激光的层析成像测量技术可以在空间和时间上以前所未有的分辨率跟踪湍流结构的动态。大规模并行超级计算机上的直接数值模拟已经发展到这样一个水平，即在足够高的雷诺数和出现超结构的参数范围内，可以模拟扩展域中的湍流。在应用数学中，已经发展了有效的方法来表征主导涡和流动结构，并确定跨边界的输运以及它们的动力学演化。计算机科学提供了在非常大的数据集中进行结构可视化和快速处理的有效算法，本优先方案的目的是综合各种最新进展，以全面表征和理解湍流上层结构。更详细地说，这包括上层结构的实验表征，湍流大尺度和上层结构的直接数值模拟，以及它们的检测和识别不同的拉格朗日和欧拉方法。此外，我们想从初级和次级不稳定性分析湍流超结构的起源，对称性和边界条件对它们的形成和动力学的作用。我们想了解它们在湍流输运中的作用，特别是它们的界面。最后，我们希望开发简化模型来有效地描述它们的动态，并开发控制这些结构的策略。为了保持程序的重点，它的目的是研究单相，在简单的笛卡尔和平行的几何形状，由剪切或浮力驱动的壁面有界流动。只有通过联合各学科的力量，我们才能更好地表征湍流超结构，提取有关其基本性质的信息，从而全面了解它们对湍流统计和湍流输运的影响。