Trigger turbulent bands directly at low Reynolds numbers in channel flow using a moving-force technique
Trigger turbulent bands directly at low Reynolds numbers in channel flow using a moving-force technique
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使用移动力技术直接在通道流中的低雷诺数处触发湍流带
DOI：
10.1017/jfm.2020.636
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发表时间：
2020-11-25
影响因子：
3.7
通讯作者：
Xiao, Xiangkai
中科院分区：
文献类型：
--
作者：
Song, Baofang;Xiao, Xiangkai
摘要 我们展示了一种用于直接数值模拟的方法，可以在通道流中直接以低雷诺数触发和维持湍流带。关键是施加一个移动的局部力，引起具有足够强的变形不稳定性的局部流动。通过该方法，我们可以触发并维持雷诺数低至 $Re\simeq 500$ 的湍流带。更重要的是，我们可以生成具有所需相对位置和方向的任何带图案。通常的扰动方法采用在较高雷诺数下模拟的湍流场、随机噪声或局部涡旋扰动，这既不能保证在低雷诺数下成功生成能带，也不能控制所生成能带的方向。对湍流带的位置和方向的精确控制对于研究低雷诺数下所有可能类型的带相互作用以及理解通道流中的亚临界转变非常重要。
Abstract We show a method, for direct numerical simulations, to trigger and maintain turbulent bands directly at low Reynolds numbers in channel flow. The key is to impose a moving localised force which induces a local flow with sufficiently strong inflectional instability. With the method, we can trigger and maintain turbulent bands at Reynolds numbers down to $Re\simeq 500$. More importantly, we can generate any band patterns with desired relative position and orientation. The usual perturbation approach resorts to turbulent fields simulated at higher Reynolds numbers, random noise or localised vortical perturbation, which neither assures a successful generation of bands at low Reynolds numbers nor offers a control on the orientation of the generated bands. A precise control on the position and orientation of turbulent bands is important for the investigation of all possible types of band interaction at low Reynolds numbers and for understanding the subcritical transition in channel flow.