Anomalous features in internal cylinder flow instabilities subject to uncertain rotational effects
Anomalous features in internal cylinder flow instabilities subject to uncertain rotational effects
复制标题
DOI：
10.1063/5.0021815
复制
发表时间：
2020-09-01
影响因子：
4.6
通讯作者：
Zayernouri, Mohsen
中科院分区：
文献类型：
--
作者：
Akhavan-Safaei, Ali;Seyedi, S. Hadi;Zayernouri, Mohsen
本文研究了在高速旋转圆柱体壁面运动中引入强破障扰动因子后的内部流动特性。我们提出并制定了一个数学上强大的随机模型的旋转运动的圆柱壁旁边的不可压缩Navier-Stokes方程的随机表示。我们采用了一个全面的随机计算流体动力学框架相结合的频谱/HP元素的方法和概率配置方法，以获得高保真实现我们的数学模型，以量化传播的参数不确定性的动态代表量的利益。我们观察到，建模的破环扰动引起的流动不稳定性所产生的壁。利用全局敏感性分析方法，我们确定了我们提出的模型中的不确定性的主要来源。接下来，我们对波动场进行定性和定量统计分析，这些波动场表征了空间和时间上强烈和快速演变的非高斯行为的指纹和措施。我们声称，这种非高斯统计基本上出现和发展，由于加强存在的相干涡运动最初触发的流动不稳定性，由于破环旋转的气缸。我们发现，这种机制会导致记忆效应的流动动力学的方式，显着的异常，在时间标度的拟能记录观察到从长远来看，除了发病的不稳定性。我们的研究结果提出了一种有效的策略来利用受控的流动不稳定性，以增强工程应用中的湍流混合。
We study the flow dynamics inside a high-speed rotating cylinder after introducing strong symmetry-breaking disturbance factors at cylinder wall motion. We propose and formulate a mathematically robust stochastic model for the rotational motion of the cylinder wall alongside the stochastic representation of incompressible Navier-Stokes equations. We employ a comprehensive stochastic computational fluid dynamics framework combining the spectral/hp element method and the probabilistic collocation method to obtain high-fidelity realizations of our mathematical model in order to quantify the propagation of parametric uncertainty for dynamics-representative quantities of interests. We observe that the modeled symmetry-breaking disturbances cause a flow instability arising from the wall. Utilizing global sensitivity analysis approaches, we identify the dominant source of uncertainty in our proposed model. We next perform a qualitative and quantitative statistical analysis on the fluctuating fields characterizing the fingerprints and measures of intense and rapidly evolving non-Gaussian behavior through space and time. We claim that such non-Gaussian statistics essentially emerge and evolve due to an intensified presence of coherent vortical motions initially triggered by the flow instability due to the symmetry-breaking rotation of the cylinder. We show that this mechanism causes memory effects in the flow dynamics in a way that noticeable anomaly in the time-scaling of enstrophy record is observed in the long run apart from the onset of instability. Our findings suggest an effective strategy to exploit controlled flow instabilities in order to enhance the turbulent mixing in engineering applications.