论文标题
各向同性湍流中长纤维的旋转和翻滚
Spinning and tumbling of long fibers in isotropic turbulence
论文作者
论文摘要
我们同时测量旋转的旋转和滚动成分，以近似和各向同性湍流中的近乎中性浮力纤维。测得的纤维的长度和直径延伸至周围湍流的kolmogorov长度的几个顺序。我们的测量结果表明，旋转速率的差异遵循-4/3功率定律的缩放，纤维直径（$ d $）始终大于翻滚速率的方差。这种行为令人惊讶地类似于以前观察到的亚基莫戈罗夫纤维。从这项研究中出现的一般图片是，长纤维优先与涡流丝的涡流丝相位，而涡旋长度可能与湍流的积分长度一样长。我们计算Lagrangian时间尺度以及支持这种前景的翻滚和旋转的分布。我们的测量值还使我们能够量化科里奥利项对湍流中纤维旋转动力学的重要性。
We simultaneously measure both spinning and tumbling components of rotation for long near-neutrally buoyant fibers in homogeneous and isotropic turbulence. The lengths and diameters of the measured fibers extend to several orders of the Kolmogorov length of the surrounding turbulent flow. Our measurements show that the variance of the spinning rate follows a -4/3 power law scaling with the fiber diameter ($d$) and is always larger than the variance of the tumbling rate. This behavior surprisingly resembles that observed previously for sub-Kolmogorov fibers. The general picture that emerges from this study is that long fibers preferentially align with vortex filaments that can be as long as the integral length of turbulence. We compute the Lagrangian time scale and the distribution of both tumbling and spinning that supports this outlook. Our measurements also allow us to quantify the importance of the Coriolis term on the rotational dynamics of fibers in turbulent flows.
