Numerical and theoretical investigation of pulsatile turbulent channel flows
Numerical and theoretical investigation of pulsatile turbulent channel flows
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DOI：
10.1017/jfm.2016.73
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发表时间：
2016-04-01
影响因子：
3.7
通讯作者：
Hanifi, Ardeshir
中科院分区：
文献类型：
--
作者：
Weng, Chenyang;Boij, Susann;Hanifi, Ardeshir
采用直接数值模拟和理论模型研究了受加频振荡影响的湍流通道流动。对不同的脉动频率进行了仿真。时间平均和相位平均的数据被用来分析流动。在此基础上讨论了扰动雷诺应力产生过程中非线性效应的开始，并报道了在DNS中观察到的新的物理特征。本文对作者提出的相干微扰雷诺剪应力的线性模型进行了回顾和深入讨论。该模型考虑了雷诺应力对周期性剪切应变响应过程中的非平衡效应，其中应力与应变之间存在相位滞后。为了验证模型的有效性，将模型得到的扰动速度和雷诺剪应力与DNS数据进行了比较。在准静态假设不成立的频率范围内，模型的性能良好。该模型所隐含的湍流涡的粘弹性特性得到了DNS数据的支持。通过在模型中加入DNS数据，对模型进行了改进。
A turbulent channel flow subjected to imposed harmonic oscillations is studied by direct numerical simulation (DNS) and theoretical models. Simulations have been performed for different pulsation frequencies. The time- and phase-averaged data have been used to analyse the flow. The onset of nonlinear effects during the production of the perturbation Reynolds stresses is discussed based on the DNS data, and new physical features observed in the DNS are reported. A linear model proposed earlier by the present authors for the coherent perturbation Reynolds shear stress is reviewed and discussed in depth. The model includes the non-equilibrium effects during the response of the Reynolds stress to the imposed periodic shear straining, where a phase lag exists between the stress and the strain. To validate the model, the perturbation velocity and Reynolds shear stress from the model are compared with the DNS data. The performance of the model is found to be good in the frequency range where quasi-static assumptions are invalid. The viscoelastic characteristics of the turbulent eddies implied by the model are supported by the DNS data. Attempts to improve the model are also made by incorporating the DNS data in the model.