旋转槽道湍流标量场输运特性数值模拟研究  

Numerical Simulation on the Scalar Transport in Rotating Channel Turbulence

作　　者：张益宁 陈洋 蔡庆东[1] 杨延涛[1] ZHANG Yi-ning;CHEN Yang;CAI Qing-dong;YANG Yan-tao(State Key Laboratory for Turbulence and Complex Systems,College of Engineering,Peking University,Beijing 100871,China)

机构地区：[1]北京大学工学院湍流与复杂系统国家重点实验室,北京100871

出　　处：《气体物理》2023年第5期46-53,共8页Physics of Gases

基　　金：国家自然科学基金(91852107)。

摘　　要：展向旋转槽道湍流中的标量场输运过程是与众多工程流动直接相关的模型问题。基于直接数值模拟工作对该问题开展系统性的研究。由壁面摩擦速度定义的流动Reynolds数固定在180,重点考察Schmidt数和旋转数的影响。结果表明,较弱旋转强度即可对主导流动结构形态产生明显的影响:此时槽道不稳定侧产生流向大尺度结构,由此导致标量场出现条带状结构。强旋转时不稳定侧出现被湍流充分混合的区域,而在稳定侧流动层流化并出现近似传导区。平均标量剖面在湍流区和层流区呈现斜率不同的线性分布。Schmidt数小于1时,湍流区标量场脉动和湍流输运随旋转数出现非单调变化,而Schmidt数大于等于1时两者都随旋转数单调下降。由此导致总标量传输率在Schmidt数小于1时随旋转数先上升后下降,而当Schmidt数大于1时单调下降且在弱旋转区域下降趋势最快。Passive scalar transport in channel turbulence with spanwise rotation is of relevance to many engineering applications.A systematical study on this problem was conducted based on direct numerical simulations.The Reynolds number defined by wall-friction velocity was fixed at 180,and the influences of the Schmidt and rotation numbers were investigated.Results reveal that even a weak rotation can have strong effects on the dominant flow structures:streamwise long streaks appear in scalar field at the unstable side due to the development of large scale streamwise rolls in the momentum field.With strong rotation,there exists a well mixed turbulent region at the unstable side,and a conductive region with near laminar flow at the stable side.The mean scalar profiles are linear in both the turbulent and conductive regions with different slopes.When the Schmidt number is smaller than unity,both the scalar fluctuation and convective transport in the turbulent region show nonmonotonic variations with rotation number,while they monotonically decrease for Schmidt number equal to or larger than unity.Therefore,for Schmidt number smaller than unity,the total flux first increases and then decreases as the rotation becomes faster.But the total flux decreases with the rotation speed when the Schmidt number is equal to or larger than unity,and it decreases fastest at small rotation speeds.

关 键 词：标量场湍流 旋转湍流 槽道湍流 直接数值模拟 湍流输运 

分 类 号：O357.5[理学—流体力学]