We investigate experimentally the defect-mediated turbulence (DMT) which is induced by bubbles injection in a Taylor-Couette flow when the inner cylinder is rotated while the outer cylinder is fixed. Bubbles of 1.2 mm in diameter are injected at the bottom of a Taylor Couette device of radii ratio equal to $0.91$. The tangential Reynolds number range is [$2200,19300$] and the air injection rate varies up to 800 ml/min. For these conditions of the experiments, bubbles are trapped in the gap by the Taylor vortices and arranged as patterns (toroidal, wavy toroidal, spirals and wavy spirals). Visualizations of the bubble patterns were carried out. When decreasing the Reynolds number or increasing the air injection rate, spiral and toroidal patterns can coexist in a composite flow. Defects occur in the bubble’s patterns (merging or splitting of the Taylor vortices pairs). By analyzing the space time diagram of bubbles patterns and their complex demodulation, we highlight different regimes and transitions in the DMT of the bubbly Taylor Couette flow. The control parameter of the transitions is the air volumetric fraction, which evolves as the ratio between the axial injection Reynolds number and the tangential Reynolds number. By increasing the air volumetric fraction, the defects in the DMT flows are classified as three flow regimes: i) structured composite flow where the defects are periodic in space and time, ii) intermittency defects chaos where the defects zones alternate randomly with the patterns in the time and space ii) developed defects chaos with a large defects density. The statistical properties of these three regimes of the DMT are analyzed in the framework of the complex Ginzburg-Landau equation.

中文翻译：

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气泡状泰勒-库埃特流中的缺陷介导的湍流

我们实验性地研究了缺陷介导的湍流（DMT），该缺陷介导的湍流是由内圆柱体旋转而外圆柱体固定时在Taylor-Couette流中注入气泡引起的。将直径为1.2 mm的气泡注入半径比等于的Taylor Couette装置的底部$0.91$。切向雷诺数范围是[$2200，19300$]，空气注入速度最高可达到800 ml / min。对于这些实验条件，气泡被泰勒涡旋捕获在间隙中，并以图案（环形，波浪形，螺旋形和波浪形螺旋形）排列。气泡图的可视化。当降低雷诺数或增加空气注入速率时，螺旋和环形模式可以并存于复合流中。气泡的图案中会发生缺陷（泰勒涡对的合并或分裂）。通过分析气泡模式的时空图及其复杂的解调，我们突出了气泡状Taylor Couette流的DMT中的不同状态和过渡。过渡的控制参数是空气体积分数，它随着轴向注入雷诺数和切向雷诺数之比的变化而变化。通过增加空气体积分数，将DMT流中的缺陷分为三种流态：i）结构复合流，其中缺陷在空间和时间上是周期性的； ii）间歇性缺陷混沌，其中缺陷区域与模式随机交替。 ii）出现了具有大缺陷密度的缺陷混沌。在复数Ginzburg-Landau方程的框架内分析了DMT的这三种状态的统计特性。ii）断续的缺陷混沌，其中缺陷区域随时间和空间随机变化； ii）缺陷密度大的缺陷混沌。在复数Ginzburg-Landau方程的框架内分析了DMT的这三种状态的统计特性。ii）断续的缺陷混沌，其中缺陷区域在时间和空间上随模式随机变化； ii）形成了具有大缺陷密度的缺陷混沌。在复数Ginzburg-Landau方程的框架内分析了DMT的这三种状态的统计特性。