论文标题
弱惯性波湍流的定量实验观察
Quantitative experimental observation of weak inertial-wave turbulence
论文作者
论文摘要
我们报告了旋转湍流的弱惯性波湍流状态的定量实验观察。我们产生一个统计稳定的均匀湍流，由非线性相互作用的惯性波组成，使用粗糙的顶部和底部边界来防止地质流动的出现。随着强迫幅度的增加，时间频谱从离散的峰会演变为连续光谱。速度场的两种形态的地图证实了在弱强迫幅度下离散波相互作用与弱湍流理论（WTT）所描述的状态之间的逐渐过渡，以实现更强的强迫。在前一个制度中，双晶图显示了接近零的背景水平，以及与离散共振相关的尖锐局部峰。相比之下，在后一种制度中，两种函数是一个平滑的函数，它符合rossby数字的值，与WTT的无限域和随机相假设一致。然后，空间光谱显示出幂律行为，频谱指数和光谱水平在高雷诺数和较低的rossby数字上都可以准确地预测。
We report the quantitative experimental observation of the weak inertial-wave turbulence regime of rotating turbulence. We produce a statistically steady homogeneous turbulent flow that consists of nonlinearly interacting inertial waves, using rough top and bottom boundaries to prevent the emergence of a geostrophic flow. As the forcing amplitude increases, the temporal spectrum evolves from a discrete set of peaks to a continuous spectrum. Maps of the bicoherence of the velocity field confirm such a gradual transition between discrete wave interactions at weak forcing amplitude, and the regime described by weak turbulence theory (WTT) for stronger forcing. In the former regime, the bicoherence maps display a near-zero background level, together with sharp localized peaks associated with discrete resonances. By contrast, in the latter regime the bicoherence is a smooth function that takes values of the order of the Rossby number, in line with the infinite-domain and random-phase assumptions of WTT. The spatial spectra then display a power-law behavior, both the spectral exponent and the spectral level being accurately predicted by WTT at high Reynolds number and low Rossby number.
