On the Characteristic Length Scale for the Synthetic Turbulence Based on the Spalart-Allmaras Model  

作　　者：Qilong Guo Pengxin Liu Chen Li Dong Sun Xianxu Yuan 

机构地区：[1]State Key Laboratory of Aerodynamics,Mianyang,Sichuan 621000,China

出　　处：《Advances in Applied Mathematics and Mechanics》2024年第1期122-145,共24页应用数学与力学进展（英文）

基　　金：supported by National Key Research and Development Program of China(No.2019YFA0405201);National Natural Science Foundation of China(Nos.12002360 and 92052301);National Numerical Windtunnel project。

摘　　要：In the hybrid RANS-LES simulations,proper turbulent fluctuations should be added at the RANS-to-LES interface to drive the numerical solution restoring to a physically resolved turbulence as rapidly as possible.Such turbulence generation methods mostly need to know the distribution of the characteristic length scale of the background RANS model,which is important for the recovery process.The approximation of the length scale for the Spalart-Allmaras(S-A)model is not a trivial issue since the model’s one-equation nature.As a direct analogy,the approximations could be obtained from the definition of the Prandtl’s mixing length.Moreover,this paper proposes a new algebraic expression to approximate the intrinsic length scale of the S-A model.The underlying transportation mechanism of S-A model are largely exploited in the derivation of this new expression.The new proposed expression is employed in the generation of synthetic turbulence to perform the hybrid RANS-LES simulation of canonical wall-bounded turbulent flows.The comparisons demonstrated the feasibility and improved performance of the new length scale on generating synthetic turbulence at the LES inlet.

关 键 词：Length scale synthetic turbulence hybrid RANS-LES Spalart-Allmaras model 

分 类 号：O357.5[理学—流体力学]