On the stress-strain alignment in premixed turbulent flames.
On the stress-strain alignment in premixed turbulent flames.
复制标题
关于预混湍流火焰中的应力-应变排列。
DOI：
10.1038/s41598-019-41599-y
复制
发表时间：
2019
影响因子：
4.6
通讯作者：
Ahmed U
中科院分区：
文献类型：
--
作者：
Ahmed U
大尺度结构和小尺度结构的相互作用是湍流能量级联的基础。这种相互作用的正确表示在大涡模拟（LES）的背景下变得重要，其中小尺度结构对解析量或大尺度结构的响应必须被参数化。当考虑预混火焰的LES时，这一具有挑战性的任务变得更加苛刻，因为热释放影响湍流和化学反应在未解决的尺度上发生的相互作用。研究了亚网格尺度应力对湍流预混火焰速度场动能收支的影响。在这种精神下，SGS的应力和解决应变率之间的对齐已被分析通过询问一个直接的数值模拟（DNS）数据库的统计平面预混火焰受到强制各向同性湍流。已经发现，SGS应力的本征向量之间的对齐和解决应变率的变化跨越火焰刷，这种变化是依赖于火焰所经历的湍流的水平。本文详细讨论了不同湍流强度和不同滤波器宽度沿着的影响以及这种错位对SGS模型的影响。
The interaction of large and small scale structures is fundamental to the energy cascade in turbulent flows. The correct representation of this interaction becomes important in the context of large eddy simulation (LES), where the response of small-scale structures to the resolved quantities, or large-scale structures, must be parametrised. This challenging task becomes more demanding when LES of premixed flames are considered, as heat release affects the interaction of turbulence and chemistry occurring at the unresolved scales. In this work, the influence of sub-grid scale (SGS) stresses on the kinetic energy budget of the resolved velocity field in turbulent premixed flames is investigated. In this spirit, the alignment between the SGS stresses and the resolved strain rate has been analysed by interrogating a direct numerical simulation (DNS) database of statistically planar premixed flames subjected to forced isotropic turbulence. It has been found that the alignment between the eigenvectors of the SGS stresses and the resolved strain rate changes across the flame brush and this change is dependent on the level of turbulence experienced by the flame. The influence of different turbulence intensities and different filter widths along with the implications of this misalignment on the SGS modelling are discussed in detail in the paper.