论文标题
湍流中热光谱中气泡引起的缩放的出现
The emergence of bubble-induced scaling in thermal spectra in turbulence
论文作者
论文摘要
我们报告通过注入大气泡的湍流中被动标量的修饰。虽然通过气泡的光谱修饰是众所周知的，并且对速度波动的分析众所周知，但在我们的情况下，气泡如何改变大约被动标量的波动，鲜为人知。在这里，我们发现了湍流多相热混合层的热光谱缩放行为。触发了$ -3 $光谱缩放的开发。通过注入大气泡（$ \ text {re} _ {\ text {bub}}} = \ Mathcal {o}（10^2）$），加气容量分数$α$最高5 \％。对于这些起泡的流动，仍然可以在中间频率下观察到$ -5/3 $缩放的低$α$，但是当$α$进一步增加时，它会变得不那么明显，随后是较大频率的陡峭$ -3 $ -3 $。 $ -3 $缩放范围随着气体量分数的增加而扩展。 $ -3 $缩放指数与高雷诺数量气泡流量的速度波动的典型能量谱图相吻合。我们确定从$ -5/3 $缩放到$ -3 $缩放的过渡的频率尺度，并显示其如何取决于气体体积分数。
We report on the modification of the spectrum of a passive scalar inside a turbulent flow by the injection of large bubbles. While the spectral modification through bubbles is well known and well analyzed for the velocity fluctuations, little is known on how bubbles change the fluctuations of an approximately passive scalar, in our case temperature. Here we uncover the thermal spectral scaling behavior of a turbulent multiphase thermal mixing layer. The development of a $-3$ spectral scaling is triggered. By injecting large bubbles ($\text{Re}_{\text{bub}} = \mathcal{O}(10^2)$) with gas volume fractions $α$ up to 5\%. For these bubbly flows, the $-5/3$ scaling is still observed at intermediate frequencies for low $α$ but becomes less pronounced when $α$ further increases and it is followed by a steeper $-3$ slope for larger frequencies. This $-3$ scaling range extends with increasing gas volume fraction. The $-3$ scaling exponent coincides with the typical energy spectral scaling for the velocity fluctuations in high Reynolds number bubbly flows. We identify the frequency scale of the transition from the $-5/3$ scaling to the $-3$ scaling and show how it depends on the gas volume fraction.
