Inspecting sound sources in an orifice-jet flow using Lagrangian coherent structures
Inspecting sound sources in an orifice-jet flow using Lagrangian coherent structures
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DOI：
10.1016/j.compfluid.2016.09.001
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发表时间：
2016-11
影响因子：
2.8
通讯作者：
V. Nair;E. Alenius;Susann Boij;Gunilla Efraimsson
中科院分区：
文献类型：
--
作者：
V. Nair;E. Alenius;Susann Boij;Gunilla Efraimsson
提出了一种新的方法来识别在经过抑制剂的受限流动中产生声音的流动结构。利用大涡模拟（LES）得到的速度场进行后处理，计算有限时间李雅普诺夫指数（FTLE）场，该场的脊在向后时间代表了拉格朗日相干结构（LCS）的近似，LCS是流场中组织输运的结构。首先利用动态模态分解（DMD）对流场进行分解，提取DMD显著频率处的组织中心或涡；然后将结果与λ2准则进行比较。与λ2判据相比，FTLE场中剪切层卷起和二次失稳发展等特征更为明显。
A novel method is proposed to identify flow structures responsible for sound generation in confined flow past an inhibitor. Velocity fields obtained using Large Eddy Simulations (LES) are post-processed to compute the Finite Time Lyapunov Exponent (FTLE) field, the ridges of which in backward time represent an approximation to Lagrangian Coherent Structures (LCS), the structures that organize transport in the flow field. The flow-field is first decomposed using dynamic mode decomposition (DMD), and the organizing centers or vortices at the significant DMD frequencies are extracted. The results are then compared with theλ2criterion. Features such as shear layer roll-up and development of secondary instabilities are more clearly visible in the FTLE field than with theλ2criterion.