Joint-constraint model for large-eddy simulation of helical turbulence
Joint-constraint model for large-eddy simulation of helical turbulence
复制标题
螺旋湍流大涡模拟的联合约束模型
DOI：
10.1103/physreve.89.043021
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发表时间：
2014
影响因子：
2.4
通讯作者：
Chen Shiyi
中科院分区：
文献类型：
--
作者：
Yu Changping;Xiao Zuoli;Shi Yipeng;Chen Shiyi
提出了一种适用于螺旋湍流大涡模拟的三项混合亚格子尺度应力模型。新模型包括Smagorinsky-Lilly项、速度梯度项和对称涡度梯度项。在动能和螺旋度通量的联合约束下，通过最小化真实的Leonard应力和模拟的Leonard应力之间的均方误差来确定模型系数。这样形成的模型称为联合约束动态三项模型(JCD3TM)。首先，利用具有螺旋强迫的均匀各向同性湍流的直接数值模拟(DNS)资料对新模型进行了评估。结果表明，JCD3TM中所有三项的SGS耗散分数在惯性子区都具有长度-尺度不变性。无论在点向意义还是在统计意义上，JCD3TM都比动态Smagorinsky模型(DSM)和动态混合螺旋模型(DMHM)更能准确地预报SGS应力、能流和螺旋度通量。然后，对JCD3TM在较少强迫和自由衰减螺旋各向同性湍流的情况下的性能进行了测试。结果表明，JCD3TM在预报能谱、螺旋度谱、高阶统计量等方面比其他两个模型具有一定的优越性，而且在衰减螺旋湍流中，JCD3TM能更准确地模拟能谱和螺旋度谱的演化。我们认为，本文的SGS模型能够捕捉到湍流运动的主要螺旋特征，可以作为研究螺旋湍流大涡模拟的有用工具。
A three-term mixed subgrid-scale (SGS) stress model is proposed for large-eddy simulation (LES) of helical turbulence. The new model includes a Smagorinsky-Lilly term, a velocity gradient term, and a symmetric vorticity gradient term. The model coefficients are determined by minimizing the mean square error between the realistic and modeled Leonard stresses under a joint constraint of kinetic energy and helicity fluxes. The model formulated as such is referred to as joint-constraint dynamic three-term model (JCD3TM). First, the new model is evaluateda prioriusing the direct numerical simulation (DNS) data of homogeneous isotropic turbulence with helical forcing. It is shown that the SGS dissipation fractions from all three terms in JCD3TM have the properties of length-scale invariance in inertial subrange. JCD3TM can predict the SGS stresses, energy flux, and helicity flux more accurately than the dynamic Smagorinsky model (DSM) and dynamic mixed helical model (DMHM) in both pointwise and statistical senses. Then, the performance of JCD3TM is testeda posterioriin LESs of both forced and freely decaying helical isotropic turbulence. It is found that JCD3TM possesses certain features of superiority over the other two models in predicting the energy spectrum, helicity spectrum, high-order statistics, etc. It is also noteworthy that JCD3TM is capable of simulating the evolutions of both energy and helicity spectra more precisely than other models in decaying helical turbulence. We claim that the present SGS model can capture the main helical features of turbulent motions and may serve as a useful tool for LES of helical turbulent flows.