基于当地流动结构的RANS/LES混合模型
收稿日期: 2013-11-11
修回日期: 2014-01-16
网络出版日期: 2014-02-21
基金资助
国家自然科学基金 (11002014)
A RANS/LES Hybrid Model Based on Local Flow Structure
Received date: 2013-11-11
Revised date: 2014-01-16
Online published: 2014-02-21
Supported by
National Natural Science Foundation of China (11002014)
针对传统雷诺平均Navier-Stokes/大涡模拟(RANS/LES)混合模型固有的RANS和LES区域衔接难题,借鉴Vreman提出的亚格子(SGS)模型,提取其中描述流动状态的判断函数,利用不可压缩槽道湍流标定模型系数,构造了一个新的RANS/LES混合模型.评估算例包括不可压缩槽道湍流、稳态超声速平板边界层、NACA4412翼型绕流和亚临界雷诺数圆柱绕流.该模型作为壁面模化LES,解决了传统RANS/LES方法中速度型偏离对数律(LLM)的缺陷,且拓宽了原Vreman模型在粗糙网格上的适用性,具有较高精度.该模型同时解决了模化应力折损问题,且对大尺度分离流动的模拟精度相较传统的RANS/LES混合模型如脱体涡模拟(DES)有进一步提升.
关键词： 湍流模型; 混合RANS/LES; 大尺度分离; 大涡模拟; 脱体涡模拟
徐晶磊 , 高歌 , 杨焱 . 基于当地流动结构的RANS/LES混合模型[J]. 航空学报, 2014 , 35(11) : 2992 -2999 . DOI: 10.7527/S1000-6893.2013.0522
In order to overcome the inherent deficiency of the traditional Reynolds Averaged Navier-Stokes/large eddy simulation (RANS/LES) hybrid model, i.e., 'the bridging problem of RANS and LES', a discriminating function extracted from Vreman's subgrid-scale (SGS) model, which is used to describe flow regimes, is employed to formulate a new RANS/LES hybrid model. The model coefficients are calibrated by incompressible turbulent channel flows. The test cases include incompressible turbulent channel flows, stable-state supersonic boundary layers over a flat plate, flow past NACA4412 airfoil and flow past a circular cylinder at subcritical Reynolds numbers. This new model is not only able to solve the modeled-stress-depletion problem, but also greatly raises the accuracy when compared with the traditional RANS/LES hybrid approach, such as detached eddy simulation (DES) in predicting large-scale unsteadiness. Furthermore, the model can also solve the log-layer mismatch (LLM) problem when RANS/LES hybrid is employed as wall modeled LES, thus extending the ability of Vreman's LES model in dealing with coarse meshes. The accuracy is greatly improved.
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