Aeroacoustic simulation of broadband sound generated from low-Mach-number flows using a lattice Boltzmann method
Aeroacoustic simulation of broadband sound generated from low-Mach-number flows using a lattice Boltzmann method
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使用格子玻尔兹曼方法对低马赫数流产生的宽带声音进行气动声学模拟
DOI：
10.1016/j.jsv.2019.115044
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发表时间：
2020
影响因子：
4.7
通讯作者：
M. Furukawa
中科院分区：
文献类型：
--
作者：
K. Kusano;Kazutoyo Yamada;M. Furukawa
本文论证了基于壁面分辨网格的晶格玻尔兹曼方法（LBM）的数值方法对低马赫数湍流边界层产生的宽带声的预测能力。该方法基于D2Q9和D3Q15模型的点阵BGK方程，提出了一种采用分层精细化网格的多尺度方法，可以有效地同时捕获近壁湍流涡流和远场声波的多尺度现象。采用四阶隐式滤波抑制了网格分辨率不足引起的数值不稳定性。讨论了该数值方法在两个基准问题中的应用，以及在湍流边界层产生的宽带声预测中的应用。首先，利用脉冲传播问题对LBM方案的计算精度和速度进行了评估。结果表明，LBM在求解可压缩Navier-Stokes （NS）方程时的精度可与采用四阶龙格-库塔方法的四阶中心格式相媲美，计算速度快12.3倍。这些结果表明，LBM是一种有效的气动声学模拟计算方法。其次，通过模拟雷诺数为150、马赫数为0.2的圆柱气流产生的风成调，验证了所提方法的有效性。本文的模拟与采用高阶有限差分格式的可压缩声波模拟在声波剖面和传播速度方面进行了比较。验证结果表明，该方法可用于低马赫数流动的直接气动声学模拟。最后，通过对雷诺数为2.0× 10.5、马赫数为0.058的隔离翼型上短分离泡产生的湍流进行壁面分辨模拟，验证了该方法预测宽带声的能力。模拟结果与表面压力分布、尾流速度分布和远场声谱的测量结果吻合较好。与基于不可压缩NS方程的混合方法相比，该方法可以通过模拟翼型上的声散射来准确预测高频范围内的宽带声。
The present paper demonstrates the capability of a numerical method based on the lattice Boltzmann method (LBM) with wall-resolved grid to predict the broadband sound generated from the turbulent boundary layer at low Mach numbers. The present method is based on the lattice BGK equation with the D2Q9 and D3Q15 models, and a multi-scale approach using hierarchically refined grids is proposed to efficiently and simultaneously capture the multi-scale phenomena of turbulent eddies near walls and far-field sound waves. Numerical instabilities caused by the lack of grid resolution are suppressed with a fourth-order implicit filtering scheme. This numerical method is discussed in two benchmark problems and an application to the prediction of the broadband sound generated from the turbulent boundary layer. First, the computational accuracy and speed of the LBM scheme are assessed with a pulse-propagating problem. The results indicate that the LBM can achieve accuracy comparable to the fourth-order central scheme with the four-stage Runge-Kutta method for the compressible Navier-Stokes (NS) equations and compute 12.3 times faster. These findings suggest that the LBM is an efficient computational method for aeroacoustic simulations. Second, the proposed method is validated by simulating the Aeolian tone generated by the flow past a circular cylinder at Reynolds number of 150 and Mach number of 0.2. The present simulation is compared with a compressible NS simulation using a high-order finite difference scheme in terms of the wave profile and the propagation speed of the tonal sound. This validation result suggests that the present method is available for direct aeroacoustic simulations of low-Mach-number flows. Finally, the capability of the present method to predict the broadband sound is demonstrated by conducting a wall-resolved simulation for the turbulent flow generated by a short separation bubble over an isolated airfoil at Reynolds number of 2.0× 10 5 and Mach number of 0.058. This simulation shows a good agreement with measurements of the surface pressure distributions, the wake velocity profiles, and the far-field sound spectrum. In contrast to hybrid approaches based on the incompressible NS equations, the present method can accurately predict the broadband sound in the high-frequency range by simulating the acoustic scattering on the airfoil.