摘要
多尺度旋涡现象广泛地存在于工程领域的湍流中.研究湍流的重要方法是大涡模拟,但大涡模拟中的过度耗散问题是曲面边界、多尺度旋涡模拟所面临的主要困难.为了克服过度耗散的缺陷,使大曲率曲面边界的多尺度涡流脉动特性预报更准确,文章采用正则化变分多尺度模型(RVM)改进了壁面自适应涡黏模型(WALE)中的亚格子模型,并采用C++语言在Open FOAM开源平台实现了计算代码编译.文章以经典圆柱黏性绕流作为曲面边界黏性绕流的代表,讨论了改进的大涡模型(MWALE)中滤波算子对亚临界雷诺数(Re=4.0×10^(4))波算子阶数(n)敏感.四阶滤波算子(n=2)能准确地预报圆柱壁面的平均涡量及尾流瞬时涡量分布、再循环旋涡长度和速度剖面,而二阶滤波算子(n=1)无法准确地预测分离区和尾流区内脉动速度剖面,因此在强压力梯度区四阶滤波算子预测的压力分布、脉动升阻力与实验结果吻合的更好,能更准确地捕捉到多尺度旋涡结构.
Multiscale vortex flows are found in many engineering applications.The principal method for studying turbulence is large eddy simulation(LES).However,the over-dissipative behavior of LES poses a special difficulty in the simulation of multiscale vortex flows that occur over strongly-curved surfaces.In order to overcome the over-dissipation behavior,and make the prediction of fluctuating characteristics with multiscale vortex flow over curved surfaces more accurate,the regularized variational model(RVM)was adopted to improve the sub-grid scale model in the wall-adapting local eddy-viscosity model(WALE),leading to the development of the modified wall-adapting local eddy-viscosity model(MWALE).The modification was implemented in C++language in the OpenFOAM software.Using the classical case of viscous flow around cylinder,the influence of filter operator on predicting performance of massive and multiscale vortex shedding at subcritical Reynolds number(Re=4.0×10^(4))is considered in this paper.Computational results show that the improved model is sensitive to the order(n)of the filtering operator.Fourth-order filter operator(n=2)can accurately predict the distribution of mean vorticity on the cylinder surface,and the instantaneous vorticity in the wake.Also well predicted are the recirculation zone length and the mean-velocity profiles.However,the second-order filter operator(n=1)cannot accurately predict the fluctuating velocity profiles in the reversed-flow and the wake region.It is found that the predicted pressure distribution in the strong pressure-gradient region,the fluctuating lift and drag forces and the multiscale vortex structures using the fourth-order filter operator are in close agreement with the experimental data.
作者
唐聃
戴绍仕
谷慧群
Bassam A.Younis
Tang Dan;Dai Shaoshi;Gu Huiqun;Bassam A.Younis(College of Shipbuilding Engineering,Harbin Engineering University,Harbin 150001,China;University of California,Davis,California 95616,USA)
出处
《力学学报》
EI
CAS
CSCD
北大核心
2024年第1期58-69,共12页
Chinese Journal of Theoretical and Applied Mechanics
基金
国家自然科学基金资助项目(11472087和11002038)。
关键词
多尺度涡流
改进的大涡模型
滤波算子
圆柱绕流
multiscale vortex flow
improved large eddy simulation model
filter operator
flow around a cylinder
