FOR 1182: Transport and Structure Formation in Turbulent Rayleigh-Bénard, Taylor-Couette and Pipe Flows near Solid Walls

湍流的描述和理解仍然是工程科学和经典物理学的最大挑战之一。强烈的时空波动和流动结构之间的耦合在不同的时间和空间尺度上限制了直接数值模拟的应用，并需要在许多实际情况下的湍流建模。只有在某些情况下才能得到准确的结果。自然界和技术中几乎所有的湍流都以固体壁为边界。在它们附近，不同大小的结构之间的强烈相互作用主导了动力学。本文从普朗特边界层概念出发，用对称性论证加以改进，得到了许多关于湍流场量平均廓线的重要结果。尽管如此，计算全球迁移量所必需的平均分布和比例指数的不确定性，导致预测的全球迁移量出现数量级不等的变化。一个重要的例子是热对流中的热传递。基于最近对固体壁附近湍流动力学的新见解和观察，我们的研究单位将专注于壁附近的局部动力学过程和全球输运特性之间的联系。通过比较迄今为止分别研究的三种基本流动，可以预期在理解上的进展：从下面加热的单元中的热对流（Rayleigh-Bénard），两个同心旋转圆柱之间的剪切湍流（Taylor-Couette）和管道中的压力驱动湍流。我们的调查将改善全球运输法。此外，他们打开的角度来控制湍流动力学在附近的墙壁，并改善模型中的复杂流动的建模与强烈减少自由度。

The description and understanding of turbulent flows is still one of the biggest challenges of engineering sciences and classical physics. The strong spatio-temporal fluctuations and couplings between flow structures at different scales in time and space limit the application of direct numerical simulations and require the modelling of turbulence in many practical situations. Only in some cases exact results can be obtained. Nearly all turbulent flows in nature and technology are bounded by solid walls. In their vicinity, strong interactions between differently sized structures dominate the dynamics. Starting with Ludwig Prandtls boundary layer concept, refined by symmetry arguments, many important results on mean profiles of turbulent field quantities have been obtained. Nevertheless, uncertainties in the mean profiles and scaling exponents, which are necessary for the calculation of global transport quantities, lead to variations in the predicted global transport that can vary by orders of magnitude. An important example is the heat transfer in thermal convection. Based on recent new insights and observations on the dynamics of turbulence near solid walls, our Research Unit will focus on the connection between local dynamical processes near the walls and global transport properties. Progress in understanding is expected by comparison of three fundamental flows that have been studied so far separately: thermal convection in a cell heated from below (Rayleigh-Bénard), shear turbulence between two concentric and rotating cylinders (Taylor-Couette) and pressure-driven turbulence in a pipe. Our investigations will improve the global transport laws. Furthermore, they open perspectives to control the turbulent dynamics in the vicinity of walls and to improve the modelling of complex flows in models with strongly reduced degrees of freedom.