壁湍流多尺度相干结构复涡黏模型的实验研究  

EXPERIMENTAL RESEACH ON COMPLEX EDDY VISCOSITY MODELING OF MULTI-SCALE COHERENT STRUCTURES IN WALL TURBULENCE

作　　者：郭爱东[1,2] 姜楠[1,3] 

机构地区：[1]天津大学力学系,天津300072 [2]军事交通学院装运机械系,天津300161 [3]天津市现代工程力学重点实验室,天津300072

出　　处：《力学学报》2010年第2期159-168,共10页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金(10832001;10872145);教育部高等学校新世纪优秀人才支持计划;天津市科技发展计划(06TXTJJC13800);上海市应用数学和力学研究所对外开放课题资助项目~~

摘　　要：在湍流相干结构动力学方程中,非相干结构成分对相干结构贡献的雷诺应力的模型为涡黏性模型,即涡黏性系数乘以相干结构平均速度变形率的形式.基于非相干结构成分对相干结构贡献的雷诺应力与相干结构速度变形率之间存在相位差的事实,在理论上提出了非相干结构成分对相干结构贡献的雷诺应力复涡黏性模型的假设.应用热线测速技术,在低速风洞中对湍流边界层非相干结构成分对相干结构贡献的雷诺应力与相干结构法向速度变形率之间的相位关系进行了实验测量.通过分析湍流相干结构猝发过程中非相干结构成分对相干结构贡献的雷诺应力与相干结构速度变形率之间的相位关系,研究了相干结构雷诺应力分量与流向速度法向梯度之间的相位差沿湍流边界层法向的变化规律,肯定了湍流相干结构复涡黏性系数模型的合理性.In the dynamics equation of coherent structures with periodical phasic average,Reynolds stress term rij=-（〈u′iu′j〉-￣u′iu′j） that noncoherent structures contributes to coherent structures,is taken into the model, in which the velocity strain rate of coherent structures is multiplied by a complex eddy viscosity coefficient,as follows：rij=vT[ ui/ xj＋ uj/ xi],1/δij（rkk）where vT is a complex eddy viscosity coefficient. Eddy viscosity coefficient is defined to be a complex,supposing that there exist phase difference between velocity strain rate of coherent structures and the Reynolds stress. The phase relation has been experimentally measured between velocity distortion（ u/ y） of multi-scales coherent structures in turbulent boundary layer over smooth plate and the Reynolds stress,r12 and analyzed in a close-circuit low-speed wind tunnel based on the expression r12=vT[ u/ y＋ v/ x]. Through the phase difference analysis between the Reynolds stress and the velocity distortion of coherent structures in wall turbulence during the bursting process of coherent structures,conclusions can be drawn as following： Relaxation time in dynamic interaction between the turbulence of coherent structures with macroscopical scale and movement distortion of coherent structures can＇t be ignored.Hence,there exist phase difference between Reynolds stress component that noncoherent structures contribute to coherent structures and the velocity distortion of coherent structures.It is an important factor that needs to be taken into account for eddy viscosity modeling theory for non-steady turbulence macrostructure. The above phase difference depends on not only the scale of coherent structures,but also the detail of physical burst process of coherent structures,such as eject and sweep.The phase of the Reynolds stress is posterior than that of velocity distortion of coherent structures in ejecting process,while anterior in sweeping process.In addition,phase difference between them does not vary with boundary

关 键 词：湍流边界层 多尺度相干结构 复涡黏性模型 雷诺应力 相位差 

分 类 号：O357.5[理学—流体力学]