The interaction of turbulent flows with the external structure of ground vehicles generates uncomfortable noise and a lot of attention is devoted to find new mechanisms for its suppression. The present work is concerned with open cavity flows, very often found in the automotive industry. A three-dimensional rectangular very wide open cavity with aspect ratio \(L/D=4\) at Reynolds number \(Re_D=5000\) and Mach number \(M=0.1\) is considered. The passive control technique is based on eight different geometrical modifications: the length of the cavity, the radius of the trailing, leading and bottom edges and the difference in heights between the left and right wall of the cavity. Wall-resolved Large Eddy Simulations (LES) are used to obtain the flow fields and a post-process based on Curle’s analogy is applied to evaluate the acoustic radiation and the effectiveness of the control mechanisms. The results show that the modifications on the trailing edge are the most effective to control the flow. They allow to reduce the pressure fluctuations produced by the recirculation confined inside the cavity and the abrupt ejection of the flow at the trailing edge. As a consequence, the overall sound pressure level can be decreased up to 9 dB.

湍流与地面车辆外部结构的相互作用会产生令人不舒服的噪音，因此人们投入了大量精力来寻找抑制这种噪音的新机制。当前的工作涉及在汽车工业中经常发现的开腔流动。具有雷诺数\（Re_D = 5000 \）和马赫数\（M = 0.1 \），纵横比为\（L / D = 4 \）的三维矩形非常宽的开放腔被认为。被动控制技术基于八种不同的几何修改：腔体的长度，后缘，前边缘和底边缘的半径以及腔体左右壁之间的高度差。使用壁解析大涡模拟（LES）来获取流场，并基于Curle的类比进行后处理以评估声辐射和控制机制的有效性。结果表明，对后缘的修改最有效地控制了流量。它们允许减小由限制在腔体内的再循环以及在后缘突然排出流体而产生的压力波动。结果，总体声压级可以降低到9 dB。