The present work focuses on the study of noise generation and radiation of an infinite open three-dimensional cavity at low Mach number with laminar upstream conditions that is of interest to understand noise generation mechanisms in wall-bounded separated flows. A particular feature of this configuration is the oscillatory mode: shear layer mode or wake mode. For the parameters considered in the present study it is seen that while in shear layer mode the flow shows a two-dimensional behavior, in the wake mode the flow is three-dimensional, resulting in significantly different sound sources. The influence of the acoustic feedback mechanism in the shear layer mode has also been investigated comparing the results between different momentum thickness values at the cavity inlet. This paper presents results of sound radiated by a three-dimensional infinite open cavity with aspect ratio L/D = 4 at Reynolds number based on the cavity depth of ReD = 1500 and Mach number of M = 0.15, both for shear layer (L/θ = 67) and wake (L/θ = 84) oscillation modes. To do so, Curle integral evaluated as a post-process of an incompressible solution will be used. The results are compared with the resulting Curle post-process of a two-dimensional incompressible simulation.

中文翻译：

---

低马赫数下开放腔辐射的噪声：腔振荡模式的影响

目前的工作重点是研究具有层流上游条件的低马赫数下无限开放三维腔的噪声产生和辐射，这对理解壁面分离流中的噪声产生机制很有意义。这种配置的一个特殊特征是振荡模式：剪切层模式或尾流模式。对于本研究中考虑的参数，可以看出，在剪切层模式下，流动表现出二维行为，而在尾流模式下，流动是三维行为，导致明显不同的声源。还研究了剪切层模式中声反馈机制的影响，比较了腔入口处不同动量厚度值之间的结果。本文基于 ReD = 1500 的腔深度和 M = 0.15 的马赫数，给出了在雷诺数下由纵横比 L/D = 4 的三维无限开放腔辐射的声音结果，均针对剪切层 (L/ θ = 67) 和唤醒 (L/θ = 84) 振荡模式。为此，将使用 Curl 积分作为不可压缩解的后处理进行评估。将结果与二维不可压缩模拟的结果卷曲后处理进行比较。