Turbulence modeling for time-dependent RANS and VLES : a review

Reynolds stress models and traditional large-eddy simulations are reexamined with a view toward developing a combined methodology for the computation of complex turbulent flows. More specifically, an entirely new approach to time-dependent Reynolds-averaged Navier-Stokes (RANS) computations and very large-eddy simulations (VLES) is presented in which subgrid scale models are proposed that allow a direct numerical simulation (DNS) to go continuously to a RANS computation in the coarse mesh/infinite Reynolds number limit. In between these two limits, we have a large eddy simulation (LES) or VLES, depending on the level of resolution. The Reynolds stress model that is ultimately recovered in the coarse mesh/infinite Reynolds number limit has built in nonequilibrium features that make it suitable for time-dependent RANS. The fundamental technical issues associated with this new approach, which has the capability of bridging the gap between DNS, LES and RANS, are discussed in detail. Illustrative calculations are presented along with a discussion of the future implications of these results for the simulation of the turbulent flows of technological importance.

重新审视雷诺应力模型和传统的大涡模拟，旨在开发一种用于计算复杂湍流的组合方法。更具体地说，提出了一种全新的非定常雷诺平均纳维 - 斯托克斯（RANS）计算和超大涡模拟（VLES）方法，其中提出了亚格子尺度模型，该模型允许直接数值模拟（DNS）在粗网格/无限雷诺数极限下连续过渡到RANS计算。在这两个极限之间，根据分辨率水平，我们有大涡模拟（LES）或VLES。在粗网格/无限雷诺数极限下最终得到的雷诺应力模型具有内置的非平衡特性，使其适用于非定常RANS。详细讨论了与这种能够弥合DNS、LES和RANS之间差距的新方法相关的基本技术问题。给出了说明性计算，并讨论了这些结果对具有技术重要性的湍流模拟的未来影响。