Deterministic Turbulence

“湍流是经典物理学中最重要的悬而未决的问题”(理查德·费曼)，因为它具有高度的非线性和混沌行为。因此，人们普遍认为，即使在相同的初始和边界条件下(即蝴蝶效应)，湍流也是不可重复的。然而，最近，由卡查诺夫教授(该提议的访问研究员)领导的一个俄罗斯研究小组在层流向湍流过渡的很晚阶段观察到了一组可重复的流动，就其统计而言，可以认为是湍流。这些被称为决定论湍流。与“普通”湍流不同，确定性湍流使我们能够预测在流动中发生的湍流事件的准确时间和位置。人们还可以回顾流动历史以了解湍流事件的原因。这为湍流研究提供了一个令人兴奋的机会，这是以前不可能的。在这里，我们建议利用确定性湍流来更好地了解湍流边界层结构，以期开发一种创新的湍流控制策略，并优化现有的流动控制技术。

"Turbulence is the most important unsolved problem of classical physics" (Richard Feynman) due to its high non-linearity and chaotic behaviour. Therefore, it has been widely accepted that turbulence is not repeatable even with identical initial and boundary conditions (i.e. the butterfly effects). Recently, however, a Russian research group led by Prof Kachanov (Visiting Researcher of this proposal) observed a certain set of repeatable flows in a very late stage of laminar-to-turbulent transition, which can be considered as turbulence as far as its statistics are concerned. These are called deterministic turbulence. Unlike "ordinary" turbulence, the deterministic turbulence allows us to predict the exact time and location of turbulence events that take place in the flow. One can also go back the flow history to see the cause of turbulence events. This provides an exciting opportunity for turbulence research that has not been possible before. Here we propose to utilise the deterministic turbulence to better understand the turbulent boundary-layer structures with a view to develop an innovative strategy for turbulence control and optimise existing flow control techniques.