Identifying eigenmodes of averaged small-amplitude perturbations to turbulent channel flow
Identifying eigenmodes of averaged small-amplitude perturbations to turbulent channel flow
复制标题
DOI：
10.1017/jfm.2019.520
复制
发表时间：
2019-07
影响因子：
3.7
通讯作者：
A. Iyer;F. Witherden;S. Chernyshenko;P. Vincent
中科院分区：
文献类型：
--
作者：
A. Iyer;F. Witherden;S. Chernyshenko;P. Vincent
平均小振幅扰动的湍流通道流的本征模-这是最基本的规范流之一-被确定为第一次通过一个广泛的高保真图形处理单元加速直接数值模拟。虽然系统平均小幅扰动湍流通道流仍然未知，事实上，这样的本征模式可以识别构成直接证据，它是线性的。此外，虽然发现与最慢衰减的反对称本征模模式相关联的本征值是真实的，但发现与最慢衰减的对称本征模模式相关联的本征值是复数。这表明，未知的线性系统的平均小振幅扰动的演变不能是自伴的，即使是单向流动的情况下。除了阐明方面的流动物理，研究结果提供了新的非定常雷诺平均Navier-Stokes湍流模型的发展指导，并构成了一个新的和可访问的基准问题，用于评估现有的模型，这是广泛使用的整个行业的性能。
Eigenmodes of averaged small-amplitude perturbations to a turbulent channel flow – which is one of the most fundamental canonical flows – are identified for the first time via an extensive set of high-fidelity graphics processing unit accelerated direct numerical simulations. While the system governing averaged small-amplitude perturbations to turbulent channel flow remains unknown, the fact such eigenmodes can be identified constitutes direct evidence that it is linear. Moreover, while the eigenvalue associated with the slowest-decaying anti-symmetric eigenmode mode is found to be real, the eigenvalue associated with the slowest-decaying symmetric eigenmode mode is found to be complex. This indicates that the unknown linear system governing the evolution of averaged small-amplitude perturbations cannot be self-adjoint, even for the case of a uni-directional flow. In addition to elucidating aspects of the flow physics, the findings provide guidance for development of new unsteady Reynolds-averaged Navier–Stokes turbulence models, and constitute a new and accessible benchmark problem for assessing the performance of existing models, which are used widely throughout industry.