摘要
采用理论分析和数值模拟相结合的方法,系统研究了尺度自适应模拟(scale-adaptive simulation,SAS)和大涡模拟(large-eddy simulation,LES)的关联性问题.在理论分析方面,对比分析了系综平均和滤波的定义、Spalart-Allmaras(SA)湍流模型和动态亚格子(subgrid-scale,SGS)模型关于湍流黏性系数的求解方式.理论分析结果表明,系综平均等价于盒式直接滤波,SAS和LES的控制方程在数学形式上具有一致性;SAS存在过多的湍流耗散,主要来自于SA输运方程中的扩散项.在数值模拟方面,选取来流Mach数0.55,Reynolds数2×10~5的圆柱可压缩绕流为分析算例.计算结果表明,SAS和LES预测的大尺度平均流场信息几乎一致,SAS预测的湍流脉动信息略低于LES.SAS在圆柱近尾迹区的湍流耗散过大,而在稍远的尾迹区几乎能够完全等效于LES.
The relationships between scale-adaptive simulation（SAS） and large-eddy simulation（LES） have been investigated systematically using theoretical analysis and numerical simulation techniques.In the theoretical analysis,some key factors were compared,including the definitions of ensemble average and filter,resolving approaches of the turbulent viscosity coefficient in the Spalart-Allmaras（SA） turbulence model and dynamic subgrid-scale model.Theoretical results show that ensemble average is equivalent to the box filter,and governing equations of SAS is corresponding to that of LES.Extra turbulent dissipation exists in the SAS method,which results from the diffusion term of SA turbulence model.In the numerical simulation,compressible turbulent flow past a circular cylinder at free-stream Mach number 0.55 and Reynolds number2×10-5 was chosen as the comparative case.Computational results show that the time-averaged flow-field predicted by SAS is nearly same as that obtained by LES.However,turbulent fluctuations predicted by SAS is evidently less than that calculated by LES.Compared to LES,SAS displays more turbulent dissipation in the near wake of circular cylinder.Fortunately,SAS is equivalent to LES in the slightly farther wake of circular cylinder.
作者
许常悦
倪竹青
孙智
张延泰
XU Chang-yue;NI Zhu-qing;SUN Zhi;ZHANG Yan-tai(Key Laboratory of Aircraft Environment Control and Life Support,Ministry of Industry and Information Technology,Nanjing University of Aeronautics ＆ Astronautics,Nanjing 210016,China)
出处
《气体物理》
2018年第2期47-56,共10页
Physics of Gases
基金
国家自然科学基金(11572154
11202100)
江苏高校优势学科建设工程资助项目
关键词
尺度自适应模拟
大涡模拟
动态亚格子模型
可压缩湍流
圆柱
scale-adaptive simulation
large-eddy simulation
dynamic subgrid-scale model
compressible turbulence
circular cylinder
