Spanwise reflection symmetry breaking and turbulence control: plane Couette flow
Spanwise reflection symmetry breaking and turbulence control: plane Couette flow
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展向反射对称破缺和湍流控制：平面 Couette 流
DOI：
10.1017/jfm.2014.99
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发表时间：
2014
影响因子：
3.7
通讯作者：
M. Oberlack
中科院分区：
文献类型：
--
作者：
G. Chagelishvili;G. Khujadze;H. Foysi;M. Oberlack
我们提出并分析了一种新的剪切流湍流控制策略，该策略可以通过以下步骤实现：（i）在流壁处施加特别设计的沿展向非对称的种子速度扰动;（ii）后者的配置确保剪切流能量的增益和湍流展向反射对称性的破坏：这导致展向平均流的产生;（iii）这改变了湍流的自持动力学，并导致湍流水平的显著降低和湍流动能的产生。事实上，通过这种策略，剪切流瞬时增长机制被激活，形成的展向平均流是受控湍流的内在非线性组成，而不是直接引入系统。在本文中，一个弱的近壁体积强迫的目的是施加所需的特性在流动中的速度扰动。以平面Couette流为例，通过直接数值模拟验证了该格式的有效性。一个有希望的结果是：经过仔细的参数选择，强迫减少湍流动能及其生产的三分之一。该策略可以自然地应用于其他有壁流动，例如通道和边界层流动。当然，所考虑的体积力是理论上的和假设的。然而，它有助于获得有关种子速度场的设计的知识，这是必要的，以实现显着减少的湍流动能施加在流中。这是令人信服的一种新的控制策略，这可能是基于专门建造的吹/吸或riblets，通过采用的洞察力所获得的理解所获得的结果，使用本文中的调查方法。
We propose and analyse a new strategy of shear flow turbulence control that can be realized by the following steps: (i) imposing specially designed seed velocity perturbations, which are non-symmetric in the spanwise direction, at the walls of a flow; (ii) the configuration of the latter ensures a gain of shear flow energy and the breaking of turbulence spanwise reflection symmetry: this leads to the generation of spanwise mean flow; (iii) that changes the self-sustained dynamics of turbulence and results in a considerable reduction of the turbulence level and the production of turbulent kinetic energy. In fact, by this strategy the shear flow transient growth mechanism is activated and the formed spanwise mean flow is an intrinsic, nonlinear composition of the controlled turbulence and not directly introduced in the system. In the present paper, a weak near-wall volume forcing is designed to impose the velocity perturbations with required characteristics in the flow. The efficiency of the proposed scheme has been demonstrated by direct numerical simulation using plane Couette flow as a representative example. A promising result was obtained: after a careful parameter selection, the forcing reduces the turbulence kinetic energy and its production by up to one-third. The strategy can be naturally applied to other wall-bounded flows, e.g. channel and boundary-layer flows. Of course, the considered volume force is theoretical and hypothetical. Nevertheless, it helps to gain knowledge concerning the design of the seed velocity field that is necessary to be imposed in the flow to achieve a significant reduction of the turbulent kinetic energy. This is convincing with regard to a new control strategy, which could be based on specially constructed blowing/suction or riblets, by employing the insight gained by the comprehension of the results obtained using the investigated methodology in this paper.
影响因子：
4.6
作者：
B. Farrell;P. Ioannou
通讯作者：
B. Farrell;P. Ioannou