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Structural subgrid scale model based on wavelet filter for large eddy simulation of particle-laden turbulence
International Journal of Multiphase Flow ( IF 3.6 ) Pub Date : 2021-07-15 , DOI: 10.1016/j.ijmultiphaseflow.2021.103730
Yan Xiong 1, 2 , Ruwu Cai 1 , Jing Li 1 , Fei Fei 3 , Zhaohui Liu 1 , Wei Luo 4
Affiliation  

Coherent vortex structures in subgrid scale (SGS) motions are important for preferential concentration and collision of particles with small and intermediate Stokes number (Xiong et al., 2019). In this study, a new large eddy simulation (LES) strategy that combines wavelet filtered large eddy simulation with a differential filter SGS model is proposed. First, a wavelet filtered direct numerical simulation (WFDNS) enables good preservation of SGS structures due to the high compressibility and local fidelity of the wavelet filter. Second, a differential filter (DF) model, containing only a parameter related to the nominal filter width, is used to dynamically reconstruct unresolved eddies. The SGS model presented here is verified using direct numerical simulation (DNS) data for particle-laden homogenous isotropic turbulence. Compared to the classical spectral-filtered DNS (FDNS) model, the new SGS model enables to achieve better agreement with DNS results related to the dispersed-phase statistics, such as particle acceleration, particle-seen fluid kinetic energy, particle-seen Lagrangian integral time etc. Furthermore, obtained results also exhibit the advantages of a proposed model over the stochastic Langevin model in the prediction of particle dynamics, especially collision-related statistics such as radial distribution function, radial relative velocities, and particle collision rates. Moreover, the model also demonstrates good performance in application to particle-pair related statistics at different Reynolds numbers and different filter depths. This is attributed to the ability of this model to multispectrally enhance coherent vortex structures in SGS, which is promising to apply for recovering SGS effects in the LES of turbulent particle-laden flows.



中文翻译:

基于小波滤波器的结构亚网格尺度模型用于载粒子湍流大涡模拟

亚网格尺度 (SGS) 运动中的相干涡旋结构对于具有中小斯托克斯数的粒子的优先聚集和碰撞非常重要(Xiong 等,2019)。在这项研究中,提出了一种新的大涡模拟 (LES) 策略,该策略将小波滤波大涡模拟与微分滤波器 SGS 模型相结合。首先,由于小波滤波器的高压缩性和局部保真度,小波滤波直接数值模拟 (WFDNS) 能够很好地保留 SGS 结构。其次,差分滤波器 (DF) 模型仅包含与标称滤波器宽度相关的参数,用于动态重建未解析的涡流。此处介绍的 SGS 模型使用直接数值模拟 (DNS) 数据验证了载有粒子的均匀各向同性湍流。与经典的光谱滤波 DNS (FDNS) 模型相比,新的 SGS 模型能够与与分散相统计相关的 DNS 结果更好地吻合,例如粒子加速度、粒子所见的流体动能、粒子所见的拉格朗日积分此外,获得的结果还展示了所提出的模型在粒子动力学预测方面优于随机朗之万模型的优势,尤其是与碰撞相关的统计数据,如径向分布函数、径向相对速度和粒子碰撞率。此外,该模型还展示了在不同雷诺数和不同过滤器深度下应用于粒子对相关统计的良好性能。这归因于该模型在 SGS 中多光谱增强相干涡旋结构的能力,

更新日期:2021-07-27
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