Active model split hybrid RANS/LES
Active model split hybrid RANS/LES
复制标题
DOI：
10.1103/physrevfluids.7.014603
复制
发表时间：
2020-06
影响因子：
2.7
通讯作者：
S. Haering;Todd A. Oliver;R. Moser
中科院分区：
文献类型：
--
作者：
S. Haering;Todd A. Oliver;R. Moser
可靠的预测模拟复杂的流动需要一个水平的模型的复杂性和鲁棒性超过目前的雷诺平均Navier-Stokes模型的能力。必要的能力，通常可以提供良好的解决大涡模拟，但对于许多感兴趣的流动，这样的模拟是太计算密集的例行执行。原则上，混合RANS/LES（HRL）模型能够通过任意级别的建模和解决湍流过渡，将改善RANS不足和LES费用。然而，除了RANS和LES中已经存在的并发症外，这些HRL方法还导致了许多独特的并发症。这项工作提出了一种建模方法，旨在克服这些挑战。这里提出的方法依赖于分裂成三个不同的组件的湍流模型：两个负责标准的亚网格模型的角色，要么提供未解决的应力或耗散和第三个，通过创建解决湍流减少模型的长度尺度。这种公式使得HRL中的混合函数不必要。此外，分裂模型方法既减轻了简单的基于涡动粘性的模型的物理近似负担，又为模型选择提供了方便的灵活性。在分辨率足以支持额外湍流的区域，波动会在最小的局部分辨运动尺度上产生。这种主动强迫驱动系统之间的平衡RANS和网格分辨LES的分辨率和流量的任何组合，而分裂模型配方防止局部中断的总应力。该模型被证明充分发展，不可压缩的渠道流和周期性的山丘显示准确的结果，成功地避免了常见的HRL的缺点。
Reliably predictive simulation of complex flows requires a level of model sophistication and robustness exceeding the capabilities of current Reynolds-averaged Navier-Stokes models. The necessary capability can often be provided by well-resolved large eddy simulation but, for many flows of interest, such simulations are too computationally intensive to be performed routinely. In principle, hybrid RANS/LES (HRL) models capable of transitioning through arbitrary levels of modeled and resolved turbulence would ameliorate both RANS deficiencies and LES expense. However, these HRL approaches have led to a host of unique complications, in addition to those already present in RANS and LES. This work proposes a modeling approach aimed at overcoming such challenges. The approach presented here relies on splitting the turbulence model into three distinct components: two responsible for the standard subgrid model roles of either providing the unresolved stress or dissipation and a third which reduces the model length scale by creating resolved turbulence. This formulation renders blending functions unnecessary in HRL. Further, the split-model approach both reduces the physics-approximation burden on simple eddy-viscosity-based models and provides convenient flexibility in model selection. In regions where the resolution is adequate to support additional turbulence, fluctuations are generated at the smallest locally resolved scales of motion. This active forcing drives the system towards a balance between RANS and grid-resolved LES for any combination of resolution and flow while the split-model formulation prevents local disruption to the total stress. The model is demonstrated on fully-developed, incompressible channel flow and the periodic hill showing accurate results and successfully avoiding common HRL shortcomings.