Abstract A shape optimization for tonal noise generated aerodynamically at low Mach number is performed for a cylinder with polygonal cross-section. Acoustic quantities are derived from a hybrid analytical formula, with aeroacoustic sources obtained from the incompressible solution of the direct Navier-Stokes equations in 2D at Re = 150; the solid domain is modelled by an Immersed Boundary Method. The optimization is done with the Particle Swarm Optimization (PSO) technique and performed in a cluster where each cost function evaluation is an independent flow simulation. The precision on the 4 main shape parameters is set to 0.001, consistently with the convergence criteria in time, grid and swarm. Optimal shapes for minimum drag and minimum acoustic power are relatively similar. A large range between the optimal shapes is obtained: factor 1.8 for drag and 20 dB for the acoustic power. The reduction of noise is associated with long and bluffer geometries, while the louder flows are associated with highly interacting shear layers obtained with back pointing triangles. The fluctuating lift is the major quantity to control noise at fixed length, while increasing the aspect ratio tends to reduce the noise for globally all geometries. An overall correlation between mean drag and fluctuating suction is also noticed.

中文翻译：

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流过致密钝体引起的噪声的形状优化

摘要 针对具有多边形截面的圆柱体，对低马赫数下空气动力学产生的音调噪声进行了形状优化。声量来自混合分析公式，气动声源从 Re = 150 的二维直接 Navier-Stokes 方程的不可压缩解获得；实体域由浸入边界法建模。优化是使用粒子群优化 (PSO) 技术完成的，并在集群中执行，其中每个成本函数评估都是独立的流模拟。4 个主要形状参数的精度设置为 0.001，与时间、网格和群的收敛标准一致。最小阻力和最小声功率的最佳形状相对相似。获得最佳形状之间的大范围：因子 1。8 的阻力和 20 分贝的声功率。噪音的减少与长而模糊的几何形状有关，而更大的流动与用后向三角形获得的高度相互作用的剪切层有关。波动升力是控制固定长度噪声的主要量，而增加纵横比往往会降低全局所有几何形状的噪声。还注意到平均阻力和波动吸力之间的整体相关性。而增加纵横比往往会降低全局所有几何形状的噪声。还注意到平均阻力和波动吸力之间的整体相关性。而增加纵横比往往会降低全局所有几何形状的噪声。还注意到平均阻力和波动吸力之间的整体相关性。