论文标题
使用移动技术直接在通道流中直接触发湍流带
Trigger turbulent bands directly at low Reynolds numbers in channel flow using a moving-force technique
论文作者
论文摘要
我们显示了一种直接数值模拟的方法，可以直接在通道流中的低雷诺数下触发和维护湍流。关键是施加移动的局部力量，该力诱导局部流动，并具有足够强的拐点不稳定。使用该方法，我们可以以雷诺的数字触发和维护湍流带，降低到$ re \ simeq 500 $。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模式。通常的扰动方法诉诸于在较高的雷诺数，随机噪声或局部涡受动力下模拟的湍流场，这既不能确保在低雷诺数数字上成功生成频段，也不能对生成频段的方向进行控制。对湍流带的位置和方向的精确控制对于研究所有可能类型的带相互作用和理解低雷诺数下通道流中的过渡至关重要。
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 and for understanding the transition in channel flow at low Reynolds numbers.
