Li Yi, Meneveau Charles, Chen Shiyi, Eyink Gregory L
Department of Mechanical Engineering and Center for Environmental and Applied Fluid Mechanics, The Johns Hopkins University, Baltimore, MD 21218, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2006 Aug;74(2 Pt 2):026310. doi: 10.1103/PhysRevE.74.026310. Epub 2006 Aug 30.
The subgrid-scale (SGS) modeling of helical, isotropic turbulence in large eddy simulation is investigated by quantifying rates of helicity and energy cascade. Assuming Kolmogorov spectra, the Smagorinsky model with its traditional coefficient is shown to underestimate the helicity dissipation rate by about 40%. Several two-term helical models are proposed with the model coefficients calculated from simultaneous energy and helicity dissipation balance. The helical models are also extended to include dynamic determination of their coefficients. The models are tested a priori in isotropic steady helical turbulence. Together with the dynamic Smagorinsky model and the dynamic mixed model, they are also tested a posteriori in both decaying and steady isotropic helical turbulence by comparing results to direct numerical simulations (DNS). The a priori tests confirm that the Smagorinsky model underestimates SGS helicity dissipation, although quantitative differences with the predictions are observed due to the finite Reynolds number of the DNS. Also, in a posteriori tests improvement can be achieved for the helicity decay rate with the proposed models, compared with the Smagorinsky model. Overall, however, the effect of the new helical terms added to obtain the correct rate of global helicity dissipation is found to be quite small. Within the small differences, the various versions of the dynamic model provide the results closest to the DNS. The dynamic model's good performance in capturing mean kinetic energy dissipation at the finite Reynolds number of the simulations appears to be the most important aspect in accounting also for accurate prediction of the helicity dissipation.
通过量化螺旋度和能量级串速率，研究了大涡模拟中螺旋各向同性湍流的亚网格尺度（SGS）建模。假设柯尔莫哥洛夫谱，具有传统系数的斯马戈林斯基模型被证明低估了螺旋度耗散率约40%。提出了几个双项螺旋模型，其模型系数由能量和螺旋度耗散平衡同时计算得出。螺旋模型还扩展到包括系数的动态确定。这些模型在各向同性稳态螺旋湍流中进行了先验测试。与动态斯马戈林斯基模型和动态混合模型一起，它们还通过将结果与直接数值模拟（DNS）进行比较，在衰减和稳态各向同性螺旋湍流中进行了后验测试。先验测试证实，斯马戈林斯基模型低估了SGS螺旋度耗散，尽管由于DNS的有限雷诺数，观察到与预测存在定量差异。此外，在后验测试中，与斯马戈林斯基模型相比，所提出的模型在螺旋度衰减率方面可以实现改进。然而，总体而言，为获得正确的全局螺旋度耗散率而添加的新螺旋项的效果相当小。在这些小差异范围内，动态模型的各种版本提供了最接近DNS的结果。动态模型在模拟的有限雷诺数下捕获平均动能耗散方面的良好性能似乎是准确预测螺旋度耗散的最重要方面。
